RULES ADOPTED BY TEE BOARD OF REGENTS OF THE UNIVERSITY OF RABAT I BAY 2 x xq4 8 VITB REGARD TO THE REPRODUCTION OF MASTERS TRESES

la i No person or corporation may publ ish or reproduce in any manner, without the consent of the Board of Regents, a thes is which has been submitted to the University in p a r t i a l fu l f i l lm ent of the requirements for an advanced degree, (b) No-individual or corporation or other organization may publ ish quotations or excerpts fran a graduate thes i s without the consent of the author and of the Univers i ty .

POOD AN) FEEDING HABITSnOF THE TELLOWFIN TUNA, KEPT HU BIDS MACROPTERUS

IN RELATION TO ITS DISTRIBUTION IN THE CENTRAL PACIFIC REGION

A THESIS SUBMITTED TO THE GRADUATE DIVISION OF THE UNIVERSITY OF HAWAII IN PARTIAL FULFILLMENT

OF THE REQUIREMENTS FOR THE DEGREE OF MASTER OF SCIENCE

JUNE 1952

ByJohn V, R e in t je e

Approved by ^ ¿ ¿ 6 * ^ /L

/ y , « “1 / • */ / J -& L C A C c y ■

S Z - 3 S 3 G 5 i ñ ‘“ 3n o .163

TABLE OF CÛNTE1TT8 c o o .2Fsge

Acknowledgement............................... l i i

L is t of ta b le s .............. I t

L is t o f f ig u r e s . . . . . . . . . . . ............... t í

I n tr o d u c tio n .......................... 1

H istorical r s T ie w ................................ 5

M a t e r i a l s ........... 9M e th o d s .................. 17R e s u l ts .................. 24Discussion ........... 45

C o n clusio ns ........... 48Appendix .................... 51

L i te r a tu r e o l te d ........... 62

i i i

ACMaprimoaiBBT

I w ish to g r a t e f u l ly acknowledge th e h e lp g iven me by Mr« Joseph £« K ing, o th e r s t a f f members, and v e s s e l crew« o f P a c i f i c O ceanic F is h e ry In v e s t ig a t io n s f o r w ith o u t t h e i r h e lp t h i s s tu d y cou ld n o t have been made. I w ish to th an k Dr« C. H. Edmondson o f th e B ernioe P. Bishop Museum fo r h is h e lp i n th e i d e n t i f i c a t i o n o f many in v e r te b r a te o rg an ism s.

LIST OF TABLESIT

I .

I I .

I I I .

IV.

V.

V I.

V II.

D is t r ib u t io n o f y e l lo w f in e a te h and stom ach c o l l e c t io n s by c r u i s e , tim e o f y e a r , l o e a l i t y , and f i s h in g method.P a r t i a l summary from th e appendix showing th e m ajor c a te g o r ie s o f food organism s and th e p r in c ip a l components f o r a l l y e llo w fin com bined.V a r ia t io n in a re ra g s stom ach o o n ten ts w ith an In c re a s e i n s i s e o f f i s h .A ssignm ent o f i n v e r t e b r a t e groups and c e r t a i n f i s h f a m i l ie s , i d e n t i f i e d d u rin g t h i s i n v e s t ig a t io n , to th e expeoted o r r e p o r te d h a b i t a t .V a r ia t io n betw een p rey and p re d a to r h a b i ta t s as shown by th e l o c a l i t y o f o a p tu ra and th e expeoted p rov lno e o f th e food organism s* Values used f o r oom parative im portan ce have been c a lc u la te d ae averag e volume in oc p e r f i s h .V a r ia t io n in food com ponents w ith method o f o ap tu ra (a n d /o r d e p th ) f o r f i s h cap tu red w ith in t e n m ile s o f la n d . V alues u sed f o r oom parative im portance have been c a lc u la te d a s av erag e volume i n oe p e r f i s h .V a r ia t io n in food components w ith d is ta n c e from land fo r f i s h c a p tu red by lo n g lin e g e a r . V alues used f o r com para tive im portance have been c a lc u la te d as av erag e volume in oo p e r f i a h .

T i l l . V a r ia t io n in av erag e stomach c o n te n ts w ith m orning o r a f te rn o o n cap tu re*

IX* V a r ia t io n in th e m ajor c a te g o r ie s o f food organism s w ithmethod o f o ap tu re and s ic e o f f i a h . A ll f i s h tak e n byt r o l l i n g and p o le and l in e f i l i n g w ith in t e n m ile s o fla n d . Average volume in oo f o r eaoh s i s e g roup .

Ti

LISI OP FIGURES

1. C hart o f th e c o n t r a i P a c i f i c ra g io n .2 . Length freq u en cy d i s t r i b u t i o n o f a l l y e l lo w f in tu n a

m easured , f o r a l l methods o f f i s h in g combined.3 . L ength freq u en cy d i s t r i b u t i o n fo r a l l sam pled y e l lo w f in ,

f o r each method o f f i s h in g .4 . Length freq u en cy d i s t r i b u t i o n o f a l l sampled y e l lo w f in ,

f o r a l l f i s h in g methods combined.

IilRODHCTIOl^/

The y e llo w fln tu n a , Keothunnue m aoropterua (Tenrainck and S c h le g e l) -^ o c c u rs th ro u g h o u t th a warmer w a te rs o f th e P a o lf lc Ooean, being abundant betw een th e T rop io o f Canoer and th e T rop lo o f C a p rlo o m . I t i s eoono- m io a lly th e m ost im p o rta n t tu n a in th e t r o p i o a l and s u b t ro p ic a l P a c i f io .F o r exam ple, more th a n 50 p e ro e n t o f th e t o t a l tun a o a to h landed in C a l i f o r n ia d u rin g 1948 and 1949 were y e l lo w f ln . F u rth e rm o re , lo n g lin e tu n a f i s h in g , one o f th e p r in c ip a l com m ercial methods in th e e e n t r a l and w e s te rn P a o if ic a ls o r e l i e s upon th e y e l lo w fln f o r more th a n 50 p e ro e n t o f i t s o a to h . T r o l l in g r e p o r t s and o a teh re c o rd s in d io a te t h a t th e sm a lle r in d iv id u a ls a re more abundant n e a r th e sh o re s o f th e i s la n d s and con­t i n e n t s . On th e o th e r hand, e x p lo ra to ry lo n g lin e f i s h in g in th e L ine and Phoenix I s la n d s and r e p o r ts from th e Jap an ese m o th e rsh ip e x p e d itio n s show t h a t th e l a r g e r f i s h h a re a somewhat b ro a d e r d i s t r i b u t i o n . The d i s t r i b u ­t i o n and abundance o f y e l lo w f ln tu n a may be dependant upon th e d i s t r i b u t i o n and abundance o f s u i t a b le food o rgan!sm s. The p re s e n t s tu d y was i n i t i a t e d to show what r e l a t i o n s h i p , i f any , e x is te d between th e abundance and d i s t r i b u t i o n o f tu n a and p rey .

R esearch conducted u nd er th e a u s p ic e s o f th e U. S. F is h and W ild l i f e S e rv ic e a s p a r t o f th e re s e a rc h program o f th e P a c if io Oe«anio F is h e ry I n v e s t ig a t io n s , H onolu lu , T. H,

S o h a e fe r and W alford (1950) s t a t e " I t apD ears t h a t th e In d ia n Ooean y e l lo w fln tu n a should be c a l le d Heothunnus a r d e n t l v i t t a t u s (C u v ie r and V a le n c ien n es ) 1831, t h a t from th e A tla n t io Neothunnus a lb a c o ra (Lowe) 1839, and t h a t from th e P a c i f ic Heothunnus m aoropterua (Tenrdnck and S o h le g e l) 1842, u n t i l such tim e as i t i s determ ined w h e th e r o r n o t th e In d ia n Ocean form I s i d e n t i c a l w ith one o f th e o th e r tw o, in w hich o sse a r g e n t iv l t t a tu a would d is p la c e a lb a c o ra o r m ao ro p te ru a . T here i s th e f u r t h e r q u e s t io n , o f c o u rs e , w h e th e r th e A tla n t io and P a c i f ic form s shou ld n o t be c o n s id e red aubepeo ies o r v a r i e t i e s o f a s in g le s p e c ie s o f cosm opo litan d i s t r i b u t i o n . "

z

I t i s r e a l i s e d t h a t th e d i s t r i b u t i o n o f y e llo w fin may be in f lu e n c e d by many f a c to r s . Of th e s e , w a te r tem p e ra tu re is th e most obv ious and th e r e i s some ev id en ce t h a t i t l im i t s th e northw ard and southw ard d i s t r i b u t i o n as shown by Takayams and Ando (1934) and H ildeb ran d (1 9 46 ), However in th e t r o p i c a l P a c i f ic from w hich th e p re s e n t m a te r ia l was o b ta in e d i t i s u n l ik e ly t h a t w a te r te m p e ra tu re , o f i t s e l f , w i l l g r e a t ly in f lu e n o e th e h o r is o n ta l d i s t r i h i t i o n o f th e y e l lo w f in . Throughout t h i s re g io n th e s u rfa c e w a te r te m p e ra tu re s a re f a i r l y u n ifo rm . K a te r tem p e ra tu re may l im i t th e v e r t i c a l d i s t r ibu - t i o n o f th e y e l lo w f in , b u t t h i s I s s t i l l a m a tte r o f c o n je c tu re . In th e a re a o f s tu d y , th e r e f o r e , th e re i s a good o p p o rtu n ity o f d e te rm in in g i f th e abundance and d i s t r i b u t i o n o f y e llo w fin i s r e l a t e d t o an o th e r p o s s ib le p rim ary f a c t o r —th e abundance and d i s t r i b u t i o n o f fo o d . I t i s w ith t h i s f a o to r , o n ly , t h a t th e p re s e n t s tu d y i s concerned .

3

HISTORICAL REVIB*

Many c a su a l o b se rv e rs and s o i e n t i f i o i n v e s t ig a to r s have reco rded food item s from th e stomach co n ten t* o f y e llo w fin tu n a . The sp e c ie s has been im p o rtan t i n th e Japanese lo n g lin e f i s h e r y f o r many y ea rs and c o n s id e ra b le a t t e n t i o n has been p a id to th e i n v e s t ig a t io n o f th e b io lo g y o f th e y e l lo w f in . Food s tu d ie s , re p re s e n te d by stomaoh con­t e n t s , o f te n ap p ear e a r ly in th e s tu d y o f an eco n o m ica lly im p o rta n t s p e c ie s . The fo llo w in g su rv ey o f th e l i t e r a t u r e o f th e food o f th e P a c i f ic y e l lo w f in tu n a i s a rran g e d in c h ro n o lo g ic a l o rd e r .

A ish inouye (1917) r e p o r te d on th e food o f lo n g lin e caugh t tu n a s , p r i n c i p a l ly y e l lo w f in , c a p tu red in th e v i o i n i t y o f th e Bonin I s la n d s .No q u a n t i t a t i v e d a ta was g iv en , b u t he in e lu d e s th e fo llo w in g i n t e r e s t in g oomment on th e food o rg an ism s—" th e s m a lle s t was A tla n ta , a he te ropo d m o llu sk , w ith a s h e l l abou t .3 6 inoh in d ia m e te r . The l a r g e s t specim en was an in d iv id u a l o f th e sp e o ie s o f L epidopus, a r ib b o n f i s h , abou t 7 f e e t lo n g . A sq u id beak ab o u t 3 .6 lno h es long was a ls o fo u n d ." Ha re p o r te d S ym plecto teus lum inosa ( s io ) and O nyohoteu th ls fa n k s i ( s i o ) among th e s q u id s , S a r r e s te e and A canthephyra and th e phyllosom a la rv a e o f th e sp in y lo b s t e r among th e o ru s ta o e a n s , and a o o p e lid s , l a r v a l Mola n o la . f ly in g f i s h . J u v e n ile b ig -ey ed tu n a , a lb a o o re and Auxis raaru among th e f i s h e s . K iehinouye (1923) re p o r te d "They (y e llo w fin tu n a ) feed on f ly in g f i s h , c o f f e r - f i s h , some d eep -sea f i s h , o a la m a rie s , p te ro p o d s , h e te ro p o d s .H yperina am phipods, S o u i l l a 's l a r v a e and immature S q u i l l a and th e m egalops o f c r a b s ."

Anonymous (1933) In a r e p o r t o f th e Formosa Governm ent-G eneral F is h e r ie s Experim ent S ta t io n f o r 1931 b r i e f l y n o ted th e appearance o f s q u id , s a rd in e , sm all o c to p i , b a llo o n f i s h and shrim p in th e rem arks column o f a le n g th -w e ig h t re c o rd f o r y e llo w fin tu n a .

The f i r s t q u a n t i t a t iv e d a ta appeared in an anonymous r e p o r t (1934) f o r th e Japanese Bureau o f F is h e r ie s In which 10 to 20 y e llo w fin tu n a stom aohs were examined d a i ly . The food item s were c la s s e d i n t o 10 o a te g o r ie s and a t a b le showing th e number o f eaoh ap p ea rin g in each d a y 's ex am in a tio n w ith su pp lem entary n o te s l i s t i n g item s o u ts id e o f th e c a te g o r ie s . V arious r e e f f i s h e s , p e la g ic f i s h e s , sq u id s and c ru s ta c e a n la rv a e w ere re p o r te d as "a k ind o f sn a p p e r" , "a k ind o f m yotophid", na k in d o f s q u id " , "a k in d o f sh rim p ", e tc .

Okuma, Im aitum i and Uaki (1936) n o ted b r i e f l y t h a t la rg e amounts o f sm all s k ip ja c k , sh rim p , sm all c r a b s , o a ra n g id s , and b a l i s t i d s were found in y e l lo w f in stom achs o o l le c te d in In d o -P a c if ic w a te rs .

Nakamura (1936) examined th e stom ach c o n te n ts o f 57 y e l lo w f in , ran g in g in s iz e from 100 cm. to 160 cm. c a p tu red by lo n g l in e g ea r in th e w a te rs o f th e C elebes Sea. Organisms found were i d e n t i f i e d to th e m ost e x c lu s iv e c a te g o ry and th e number o f appearances and th e numbers ap p ea rin g were ta b u la te d . The r e s u l t s o f two y e a r s ' work w ere oomp&red f o r an n u al v a r i a t io n . Some m inor fau na1 changes were n o ted . C e r ta in bo ttom fa u n a l e lem en ts and some i n e r t m a te r ia ls in d ic a te d to the a u th o r t h a t some bottom fe e d in g o ccu rred in th e v l o i n l t y o f la n d , fie re p o r te d o lu p e o id , soom broid , and p le c to g n a th f i s h e s among th e most common food o rg an ism s, fo llo w ed by sq u id , p ro bab ly S y m p lec to te u th is o u a la n ie n s is , and p a l in u r ld s , s q u i l l i d s , s y l l a r i d s , and Leander among th e c ru s ta c e a n s .

4

VTalford (1937) r e p o r te d f l y ln g f i s h , s a u r ie s , s a r d in e s , s q u id s , l a r v a l and a d u l t p la n k to n ie c ru s ta c e a n s from th e stom achs o f y e l lo w fin c a p tu red by s u r fa c e f i s h in g in th e c o a s ta l w a te rs o f th e e a s te r n F a c i f io .

Anonymous (1938) re p o r te d f o r th e Formosa F is h e r ie s S o c ie ty some s e m i-q u a n t i ta t iv e d a ta w hich had been o b ta in e d d u rin g th e exam in ation o f 40 y e l lo w f in tu n a stomaohs ta k e n d u rin g lo n g lin e f i s h in g in Formosan w a te r s . Food organ ism s were i d e n t i f i e d to th e most e x o lu s iv e c a te g o ry and t a b u la te d a c co rd in g to number o f app ea ran ces and numbers a p p e a rin g . F is h , s q u id , end c ru s ta c e a n s app eared m ost im p o rta n t i n th e fo o d , however, e ig h t " J e l l y f i s h " o c c u rre d i n seven y e l lo w f in and e lev en "oo topus" in f i v e .

Marukawa (1939) examined 12 lo n g lin e caug h t y e l lo w f in from th e e q u a to r ia l w ate ra so u th o f th e P a laus and b r i e f l y summarised th e r e s u l t a i n a c h e c k l i s t o f f i s h e s , s q u id , and o ru s ta c e a n s found .

iflyam a, S aruy a , and Hasegawa (1959) examined th e s ton aoh c o n te n ts from seven y e l lo w f in tak en by lo n g lin e in th e w a te re so u th o f th e c e n t r a l C a ro lin e e and re p o r te d n e e d le f i s h , o th e r sm a ll f i s h e s , and s q u id s .

Kanamura, Masami and T asak l (1940a, 1940b) r e p o r te d th e number o f appearanoes and th e numbers o c c u rr in g f o r th e g e n e ra l c a te g o r ie s o f food o rgan ism s from lo n g lin e oaught y e l lo w fin ta k e n in th e B ast P h i l ip p in e Sea and th e South China Sea. Item s i d e n t i f i e d by oommon names o n ly as " sq u id , t r i g g e r f i s h , b a l lo o n f i s h and sh rim p ."

Ban (1941) re p o r te d on th e food o f lo n g lin e oaught y e l lo w fin in a jo u rn a l o f sem i-p o p u la r n a tu r e . The fo llo w in g e x c e rp t on th e stom ach o o n te n ts i s quo ted in i t s e n t i r e t y i

6

6

A s tu d y ex ten d in g o v e r one y e a r was made o f th e stomaoh o o n te n ts , b u t m ost o f th e m a te r ia l re co v e red was so f a r d ig e s te d t h a t i t oould n o t be i d e n t i f i e d below th e genus. I t i s d i f f i c u l t to d i s ­t in g u i s h any d i f f e r e n c e between th e sexes w ith re g a rd to th e t o t a l q u a n t i ty o f th e stomaoh c o n te n ts . Judging from t h e tim e a t whioh th e f i s h w ere ta k e n and th e p ro g re ss o f d ig e s t io n , i t ap n ears t h a t t h e f i s h fe e d a t n ig h t . I f we o la s s i f y th e stom ach o o n te n ts we f in d t h a t th e y a l l o o n s is t s o le ly o f p e la g io p la n k to n ic an im a ls .I t i s e s p e c i a l ly s u r p r i s in g t h a t in many oases la r g e numbers o f f i s h such a s s p e c ie s o f t r u n k - f i s h and hard s h e l le d m o llu sk s , l ik e th e p ap e r n a u t i l u s a re found. In o th e r e a ses ju v e n i le o a ra n g id s , m ackerel and sn h y ra sn id a , a s w e ll a s m ature s k ip ja c k (5 8 .3 - 4 0 .5 oou i n le n g th ) a re d isc o v e red in stom achs.S uyah iro (1942) b r i e f l y re p o r te d on th e stomach o o n tsn ts o f a

"sam ple" ta k e n d u rin g one d a y 's f i s h in g o f f so u th e rn Japan . In a d d i t io nto h is own o b s e rv a t io n s he r e p o r ts t h a t l e a t h e r - f i s h e s , c u t t l e f i s h e s , andsh rim p s w ere found in sam ples ta k e n n e a r Timor I s la n d . Nakamura (1943)rev iew ed th e m a te r ia l p re se n te d in h is p re v io u s p u b l ic a t io n (o£. o i t . )w ith o u t p r e s e n ta t io n o f any t a b u l a r r e s u l t s .

T in k e r (1 9 4 4 ), Chapman (1 9 4 6 ), H ildebrand (1 9 4 6 ), S h ap iro (1948),H erald (1 9 4 9 ), and F ito h (1950) b r i e f l y r e f e r r e d t o th e food o f th ey e llo w f in tu n a as c o n s is t in g o f sm all shore and p e la g io f i s h e s , sq u id sand p la n k to n ic c ru s ta c e a n s . F ito h ( i b i d . ) r e p o r ts ^ a s tu rn s la n o e o la tu s .th e p o in te d - t a i l e d s u n f is h , a s "one o f th e most common s p e c ie s found i nth e stom achs o f th e y e l lo w f in tu n a ta k e n by th e B̂ _ S c o f ie ld inH aw aiian w a te rs . . . . N early a hundred p o s t - la r v a e ran g in g i n s i t e fromo n e - fo u r th in c h to n e a r ly two in o h es In d ia m e te r w ere ta k e n from th estom aohs o f m ost o f th e 55 tu n a exam ined." He re p o r te d a seam oth,Pegasus s p . , from th e same stom aoh o o n ten ts as th e seah o rse re p o r te d byH era ld (o£ . a l t . ) .

Nakamura (1949) p re s e n te d a sem i-p o p u la r p re s e n ta t io n o f some a s p e c tso f tu n a b io lo g y , i n which a b r i e f m ention o f th e food o f th e y e llo w fin

tu n a was made. The m a te r ia l p re se n te d summarised th e f in d in g s p re v io u s ly p u b lish e d in 1936.

Tfelsh (1949) examined th e s tan ao h c o n te n ts o f 20 sm all (7 to 15 pounds) y e llo w fin tu n a c a p tu re d by t r o l l i n g in th e im m ediate v i c i n i t y o f th e n o r th e a s te r n o o a s t o f Oahu, Hawaiian I s la n d s . Organisms found were i d e n t i f i e d to th e most e x c lu s iv e o a te g o ry and measured by th e v o lu m etrio d isp lacem en t o f w a te r . The t a b u la r r e s u l t a were p re se n te d as a "compara­t i v e averag e p e rce n ta g e r a t in g " whioh was d e so r ib e d as fo llow s»"p e ro en tag e r a t in g i s average o f t o t a l p e ro e n t o f t o t a l number o f food an im als u se d , t o t a l b u lk o f food u se d , and th e t o t a l number o f stom achs

ri n w hioh food was fo u n d ." The methods used w ere n o t d e so r ib e d exo ep t in g e n e ra l te rm s and no q u a n t i t a t i v e r e s u l t s were p re s e n te d , o th e r th a n th e "p e ro en tag e r a t i n g ." A ccording to h is r a t in g method c ru s ta c e a n s were most Im p o rta n t , m a in ly stom atopods and c ra b la r v a e j f i s h were n e x t , m ainly p om fre ts and g u rn a rd s) and f i n a l l y , s q u id .

R o n q u illo (1950) examined th e stomaoh c o n te n ts from 144 y e l lo w fin tu n a e a p tu red by s u rfa o e t r o l l i n g d u rin g 1947, 1948 and 1949. Most o f th e f i s h were oaught i n th e w a te rs o f th e so u th e rn P h i l ip p in e I s la n d s .Fork le n g th and w eig h t o f th e tu n a was reo o rd ed and th e food organism s w ere i d e n t i f i e d and co u n te d . Food organ ism s were a rran g ed in a sy s te m a tic o rd e r w ith a t a b u la t io n o f th e number o f organism s found and t h e i r freq u en cy o f o c c u rre n c e . The a u th o r ( i n l i t t . ) c o n s id e rs th e s e r e s u l t s as p re lim in a ry in n a tu re and has a more com plete r e p o r t read y f o r p u b l io a t io n . P r in c ip a l food com ponents were f i s h , r e p re s e n te d by 51 fa m il ie s o f p e la g io and r e e f f i s h e s , squ id and c ru s ta o e a n la r v a e .

7

8

Two anm ual r e p o r t s from th e Kan&gawa P re fe c tu re F is h e r ie s Experim ent S ta t io n were p u b lish e d anonymously (1951a, 1951b) on th e South Seas Tuna F is h e ry I n v e s t ig a t io n s . Anonymous (1951a) re p o r te d on th e freq u en cy o f ooou rrenoe o f g e n e ra l c a te g o r ie s o f food organism s in th e stomach o o n teh ts o f 112 y e llo w fin tu n a c ap tu red by lo n g lin e f i s h in g in th e w a te rs sou th and e a s t o f th e P a la u s . Anonymous (1951b) re p o r te d th e w eig h t o f stomach c o n te n ts and t h e freq u en o y o f ooourrenoe f o r 10 c a te g o r ie s o f food organ ism s from 14 lo n g lin e cau g h t y e l lo w fin tu n a from th e e q u a to r ia l w e s te rn P a c i f i c . R om fre ts, s q u id , n e e d le f i s h , c ru s ta c e a n la r v a e , l a n t e r n - f i s h e s and p le c to g n a th f i s h e s ooourred m ost f r e q u e n t ly .

From 1917 th ro u g h 1951, twenty-Bix o f th e p ap e rs review ed r e f e r r e d to th e food o f th e y e l lo w f in tu n a from th e P a o lf ic Ocean. Of th e s e , s e v e n te e n r e f e r r e d , i n g e n e ra l t e r n s , to food organism s found w ith o u t any q u a n t i t a t i v e e v a lu a t io n , n in e re p o r te d th e freq u en o y o f ooourrenoe a n d /o r th e numbers o f o rganism s appearing and o f t h e s e , two gave some v o lu m e tr ic e v a lu a t io n to th e food found.

9

MATERIALS

T e llo w fln tun * were c a p tu red by t r o l l i n g , lo n g lin e f i s h in g and p o le and l in e f i s h in g from th e w ater« o f th e c e n t r a l P a c i f ic r e g io n d u rin g 1950 and 1951 by th e re s e a rc h v e s s e ls - ^ o f th e U. S . F i6h and W i ld l i f e S e r v i c e 's , P a c i f ic O ceanic F is h e ry In v e s t ig a t io n s .

The re g io n o f c a p tu re ( f ig u r e l ) i s bounded by 10° H. and & S. l a t i t u d e s and by th e m e rid ia n s o f 150° and 175° W. lo n g itu d e , an a re a o f 1 ,5 0 0 ,0 0 0 sq u a re m ile s o f t r o p i c a l , c e n t r a l P a c i f ic w a te r s . Two groups o f i s l a n d s a re lo c a te d w ith in th e re g io n . The Phoenix I s la n d s , composed o f e ig h t i s la n d s and one r e e f r e p re s e n t in g ap p ro x im ate ly 15 square m iles o f em ergent la n d , a re lo c a te d in th e so u th w e s te rn p o r t io n o f th e re g io n . The L ine I s la n d s l i e a lo ng th e e n t i r e e a s te rn boundary o f th e re g io n and c o n ta in seven i s la n d s and one r e e f w ith ap p ro x im ate ly 260 sq ua re m iles o f la n d . C hris tm as I s la n d acco u n ts fo r 88 p e rc e n t o f t h i s w ith 230 sq uare m ile s o f em ergent la n d . The o n ly sha llo w o r l i t t o r a l w a te r s in th e r e g io n a re found in th e im m ediate v i c i n i t y o f th e s e i s l a n d s . The o cean ic o r o f f s h o re a r e a s , w ith few e x c e p tio n s , a re w a te rs o f more th a n 2000 m eters d e p th .

The a re a may be d iv id e d i n to to n e s o r p ro v in c e s . A ccording to S verd ru p , Johnson and F lem ing (1946) th e "two p rim ary d iv is io n s o f th e se a a re th e b e n th ie and th e p e la g ic . The fo rm er in c lu d e s a l l o f th e ocean f l o o r , w h ile th e l a t t e r in c lu d e s th e whole mass o f w a te r ."Elooan (1935) su b d iv id ed th e b e n th io In to th e l i t t o r a l , n e a r sho re system

^ Manning. Henry O’M alley and Hugh M. Sm ith .

IO

FIG. I

11

a t a d ep th o f 200 m e ters o r l e s s , and th e d eep -sea system a t a l l d eep e r w ate rs» The p e la g ic d iv is io n i s d iv id e d h o r i s o n ta l ly i n to an o p en -sea (o c e a n ic ) p ro v in c e , and an in sh o re ( n e r i t i e ) province» In t r o p i c a l and s u b t r o p ic a l r e g io n s , in f lu e n c e d by sm all i s l a n d s , t h e boundary betw een th e n e r i t i e and th e o cean ic p ro v in c e s i s n o t c l e a r l y d e f in e d . This o v e rla p p in g i s pronounced where th e 200-m eter l i n e i s l e s s th a n one m ile s and th e 2000- m eter l i n e i s l e e s th a n f iv e m ile s from em ergent la n d . The o cean ic re g io n , re p re s e n te d by w ate rs o u ts id e th e in f lu e n c e o f th e o c e a n s• b o ttom s, can be su b d iv id ed i n to a re a s w ith b o u n d a rie s based upon w a te r m asses o r o u r r e n ts . The reg io n i s c h a ra c te r is e d by th e two w estw ard flo w in g e q u a to ­r i a l o u r re n ts and th e in te rv e n in g e a s t flo w in g c o u n te rc u rre n t (Cromwell 1951).

Methods and g ea r u sed were d e s c r ib e d by B ates (1950) f o r s u rfa c e t r o l l i n g , S hap iro (1950) and June ( i9 6 0 ) f o r lo n g lin e f i s h in g and by Q odeil (1938) and June (1961) f o r p o le and l in e f i s h in g . T ab le 1 shows th e number o f f i s h c a p tu red and th e number o f stom aohs c o l le c te d d u rin g th e p e r io d o f in v e s t ig a t io n on each a re a and met .od o f f i s h in g . The le n g th freq u en cy d i s t r i b u t i o n o f th e e n t i r e m easured c a tc h o f 2005 y e l lo w f in tu n a i s shown in f ig u r e 2 . The e f f e c t o f th e method (o r d e p th ) o f f i s h in g on th e s i s e o f th e f i s h r e a d i ly can be seen in f ig u r e 5 .

Stomachs w ere c o l le c te d f o r su bseq u en t la b o ra to ry exam in ation from 1097 f i s h . An a tte m p t was made to o b ta in a r e p r e s e n ta t iv e sample d u rin g each c r u i s e , f o r eaoh a re a and method o f f i s h in g . The p e rce n ta g e s o f th e c a tc h t h a t w ere sam pled a re shown i n t a b le 1. F ig u re 4 shows th e le n g th freq u en o y d i s t r i b u t i o n o f th e f i e h from which stomaohs were c o l l e c te d .

NU

MB

ER

S

FORK LENGTH IN MILLIMETERS

FIG. 2 LENGTH FREQUENCY DISTRIBUTION OF ALL YELLOWFIN TUNA MEASURED, FOR ALL METHODS OF FISHING COMBINED

NU

MB

ER

S

FORK LENGTH IN MILLIMETERS

FIG. 3 LENGTH FREQUENCY DISTRIBUTION FOR ALL SAMPLED YELLOWFIN, FOR EACH METHOD OF FISHING

NU

MB

ER

S

FORK LENGTH IN MILLIMETERS

FIG 4 LENGTH FREQUENCY DISTRIBUTION OF ALL SAMPLED YELLOWFIN FOR ALL FISHING METHODS COMBINED

l a b i a I . D is t r i b u t i o n o f y e l lo w f in c a tc h and stom ach e o l la o t io n a by c r u i s e , t in « o f y e a r , l o c a l i t y , and f i s h in g method.

Vessel C ru iseHo.

P erio d L o o a lity MethodNo. o f

y e l lo w f in c a p tu re d

o fstom aohsexamined

% o f e a to h sampled

HUS 2 Feb. 1950 Phoenix T ro l l in g 10 9 9 0 .0HUS 2 Feb. 1950 Phoenix P. A L. 4 4 100 .0JRM 2 A p r.-Ju n e 1960 Line T r o l l in g 882 105 1 1 .9HM.' 8 J u ly 1950 Ftioanix L ong line 53 52 98.1HUS 5 A lly 1950 Phoenix T ro l l in g 2 2 100 .0HOU 4 Ju ly -A ug. 1950 Phoenix T ro l l in g 24 7 20.8HOM 4 July-A ug. 1950 Fho en ix P . A L. 241 24 15.4HOU 4 Aug. 1950 Line T r o l l in g 4 2 5 0 .0HOU 4 Aug. 1960 Line P. A L. 8 5 62 .5JRM 5 Aug. 1950 Phoenix T r o l l in g 64 41 8 4 .1JKU 3 S e p t. 1950 Line T r o l l ih g 109 21 19.3HUS 7 Ho t . I960 Line T ro l l in g 5 4 8 0 .0HUS 7 Ho t . 1950 Line L ongline 132 106 8 0 .3JRU 4 Hot . 1950 Line T ro l l in g 98 96 9 8 .0

V esse lC ru ise

Ho. P erio d L o c a lity MethodNo. o f

y e l lo w f in cap tu red

No. o f stom achs examined

% o f o e to h

sampled

HMS 8 J e n .-F e b . 1951 Line T r o l l in g 25 23 9 2 .0<1RM 5 J e n .-F e b . 1951 R ioenix T ro l l in g 27 23 8 5 .2JEM 5 Feb. 1951 Line T ro l l in g 43 27 62.8JRU 6 Apr.-Mey 1951 L ine T ro l l in g 110 100 90.9HMS 9 June 1951 Line T r o l l in g 29 19 6 5 .5HUS 9 June 1951 Line P. A L. 2828 209 8 .0BUS 9 June 1951 R ioenix T r o l l in g 2 2 1 00 .0BUS 9 June 1951 Phoenix P. A L. 177 63 35.6HMS 11 A ug*-Sept. 1951 Line L ong line 457 163 33 .5

5164 1097 21.2

17

METHODS

In th e F la ld«The stom ach was removed from th e f i s h ae soon as p o s s ib le a f t e r

c a p tu r e , p lao ed to g e th e r w ith any r e g u r g i ta te d m a te r ia l in an unb leached m u s lin bag and p re se rv e d i n 10 p e rce n t fo rm a lin . In th e bag w ith each stom ach was p la c e d a l a b e l b e a r in g th e d a ta , l o c a l i t y o f o a p tu re , s p e c ie s , t o t a l l e n g th , method o f c a p tu r e , b a i t u se d , d e p th o f o a p tu re , tim e o f day, name o f o b se rv e r and v e s s e l . One o f th e fo llo w in g methods was used in rem oving th e stom achsi

1 . The abdom inal c a v i ty was opened by a lo n g i tu d in a l m id -v e n tra l i n c i s io n . The sm all i n t e s t i n e was sev ered p o s t e r i o r to th e p y lo r ic v a lv e and th e stomaoh w as f r e e d by c u t t in g th ro u g h th e m uscu la r e so p hagu s. ,

2 . The g i l l membrane was s i l t a lo ng th e l i n e o f a ttach m en t w ith*th e o le i th ru m , p o s t e r i o r to th e fo u r th g i l l a rc h . The pouoh-

l i k e stom ach was p u lle d o u t and removed by c u t t in g th ro u g h th esm a ll i n t e s t i n e and esophagus.

In th e L ab o ra to ry .At th e la b o r a to r y th e m u slin bags w ith c o n te n ts were leach ed in f r e s h

w a te r f o r 12 to 24 hours t o remove e x eess fo rm a lin . At th e tim e o f a n a ly s is each bag was em ptied in to a d is s e c t in g pan and th e la b e l was t r a n s c r ib e d to a la b o r a to r y re e o rd s h e e t . The stom ach w as s l i t lo n g i tu d in a l ly and th e stomaoh w a ll p ee led back to expose th e c o n te n ts . A ll o f t h s c o n te n ts w ere c a r e f u l ly removed and s e p a ra te d in to groups f o r subsequ en t i d e n t i f i c a ­t i o n . Each o rganism was i d e n t i f i e d as co m p le te ly as was p r a c t i c a b le and th e t o t a l number o f each s p e c ie s or g roups o f organism s was re c o rd e d .Each s u b d iv is io n o r k in d o f food was th e n m easured v o lu m e tr io a lly by th e

18

d isp la ce m e n t o f w a te r in a g rad u a ted c y l in d e r o f a p p ro p r ia te s i s e . This ap p eared to be th e most ra p id method f o r th e e v a lu a t io n o f th e food found.I f j e l l y f i s h or s im i la r organism s w ith g re a t q u a n t i t i e s o f w a te r hadocourred ,som e o th e r method fo r th e e v a lu a t io n o f th e n u t r i t i o n a l v a lu e would have been u se d , how ever, f o r f i s h , sq u id and c ru s ta c e a n s , volume seemed r e l i a b l e . W eigh t, u sed in some gam ebird and mammal food s tu d ie s ,w ould be more la b o r io u s to u se and d id n o t ap p ea r to be o f g r e a te r v a lu ed u rin g th e p re s e n t s tu d y .

The methods u sed i n th e i d e n t i f i c a t i o n o f th e food organism s and th e o rg a n ic rem ains v a r ie d to a g re a t e x te n t , dependent upon th e group o f an im als u n d e r c o n s id e r a t io n .

The a r th ro p o d s were i d e n t i f i e d to o rd e r from g e n e ra l e x o s k e le ta l c h a r a c t e r i s t i c s . A lthough E u p hausiacea , Myoidacea and Deoapoda shrim ps w ere d i f f i c u l t to s e p a r a te , th e seldom o ccu rren ce o f th e f i r s t two o rd e rs caused th e problem to be o f second ary Im po rtance , im phipoda, Isopoda , Stom atopoda and m ost Decapoda w ere v ery easy to d i s t i n g u i s h to o rd e r even w ith p a r t i a l rem a in s . The members o f th e amphipod f a m il ie s o f C a l l io p l id a e , H y p e riid a e , Cbtycephalidae and Gammaridae found in t h i s re g io n were s e p a r­a b le to fa m ily by c e r t a in c e p h a lic c h a r a c t e r i s t i c s and body sh ape . The s p e c ie s o f Stom atopoda w ere r e a d i ly d is t in g u is h e d from each o th e r by c e r t a i n e x o s k e le ta l f e a tu r e s w hich u s u a l ly p e r s i s te d even on bad ly damaged specim en s. Brooks (1 8 8 6 ), Kemp (1 9 1 3 ), Edmondson (1921), Bigelow (1931) and Townsley (1950) re p o r te d on P a c i f ic form s and c o n s tru c te d keys fo r t h e i r s e p a r a t io n . Such decapod c ru s ta c e a n s as th e p o s t l a r v a l P a lin u r id a e and N ephropsidae w ere r e a d i ly i d e n t i f i e d because each p o sse s se s u n iq ue f a m i l i a l t r a i t s . H o lth iu s (1946) re p o r te d d i s t r i b u t i o n a l and d e s c r ip t iv e n o te s on th e o e n t r a l P a c i f i c n ep h ro p s id s .

19

The s h e l le d m o llu scs found I n th e stom achs o f tu n a were r e a d i ly s e p a ra te d in to H eteropoda, P teropoda and n a u t i lo id Cephalopoda from th e d is t in g u is h a b le s h e l l rem a in s .

The cephalopoda were s e p a ra b le in to sq u id s and octopods on th e b a s is o f g e n e ra l body sh ap e , number o f arm s, p re se n c e o r absence o f a g la d iu s (p e n ) , and w hether or n o t th e su ck e rs w ere m od ified in to hooks. The p re ­sence o f t e n t a c l e s ( f i f t h p a i r o f arm s) was u sed in a l l sq u id s as a d is t in g u is h in g t r a i t ex cep t i n th e a b e r r a n t fa m ily o f e ig h t-arm ed sq u id s . O o to p o d o teu th id ae , w here th e p resen ce o f su ekers m od ified in to hooks p lao ed i t i n th e decapod m o llu sc s . B erry (1914) used th e p e r f o r a t io n o f th e e y e l id , a rrangem en ts o f su ck e rs and th e h eo to o o ty lu s (m o d if ic a tio n o f th e male a m in to an a c c e sso ry sex o rg an ) to d i s t in g u is h gen era and s p e c ie s o f oephalopods; how ever, a l l o f th e s t r u c tu r e s a re v e ry s u s c e p t ib le to th e d e s t r u c t iv e a c t io n o f th e d ig e s t iv e J u ic e s so t h a t in most in s ta n o e s organism s were i d e n t i f i a b l e o n ly a s sq u id s o r oo topods. W ith­o u t an a r t i f i c i a l key t o th e g l a d i i and m an d ib le s , l i t t l e more th an s u b o rd in a l i d e n t i f i c a t i o n cou ld be accom plished w ith th e p a r t i a l rem ains o f th e cephalopod m o llu sc s .

P e la g ic t u n ic a te s w ere seldom i d e n t i f i a b l e to fa m ily because in th e buna stom ach th e s o f t body r e a d i ly d i s in te g r a te d in to g e la t in o u s frag m en ts . These rem ains r e ta in e d c e r ta in c h a r a c t e r i s t i c s t h a t d is t in g u is h e d them from th e o o e le n te r a te s and o th e r p e la g ic organism s w ith s im i la r g e la t in o u s s t r u c tu r e .

The t e l e o s t f i s h e s were r e a d i ly i d e n t i f i e d as such from t h e i r s k e l e t a l rem ain s . F u r th e r i d e n t i f i c a t i o n , even to o r d e r ,vas dependant upon c e r t a i n d is t in g u is h a b le t r a i t s , many o f whioh were r e a d i ly l o s t . Engulfm ent o f te n se p a ra te d th e head from th e body, m u tila te d th e f i n s .

s k in , l a t e r a l l i n e , and removed s c a le s , when p r e s e n t , th u s making i d e n t i f i c a t i o n d i f f i c u l t * F ish e s w ith bony p ro tu b e ra n c e s , c a ra p a c e - l ik e in tegum ent and o th e r d is t in g u is h a b le h ard p a r ts were most e a s i ly i d e n t i f i e d . F a m il ia l i d e n t i f i c a t i o n was o f te n dependent upon s in g u la r c h a r a c t e r i s t i c s , such a s j bony s c u te s in th e C arang idae , t e e t h and m andib les in th e T e tro d o n tid & e , D lo d o n tid ae , A le p is a u r ia a e , A ulostom idae, B e lo n ld a e , and H endrham phidae. In more g e n e ra lis e d groups p o sse s s in g n e i t h e r u n iq u e n o r r e s i s t a n t p a r t s , i d e n t i f i c a t i o n could n o t be r e a d i ly made. J u v e n ile f i s h e s o f te n la e k th e u su a l t r a i t s o h a r a c te r i s t i o o f th e a d u l t s j fo r t h e s e , i d e n t i f i c a t i o n to fa m ily o f te n was im p ra c t ic a l .

B e rg 's (1940) m o d if ic a tio n o f R egan 's system o f c l a s s i f i c a t i o n w as u sed f o r th e fo ra g e f i s h e s . Fow ler (192B, 1931, 1934, 1949), Jo rd an and Evermann (1 9 0 5 ), G i lb e r t (1 9 0 5 ), Weber and De B eau fo rt (1913, 1916, 1922, 1929, 1931, 1 936 ), De B e au fo rt (1 9 4 0 ), S ch u lte (1 9 43 ), Brook (1950) and De B eau fo rt and Chapman (1951) were found t o be th e most u s e fu l re fe re n c e s t o th e f i s h e s o f th e c e n t r a l P a c i f ic re g io n ,

A re fe re n o e c o l l e c t io n o f f i s h e s and in v e r t e b r a t e s , which i s m ain­ta in e d a t th e f f e c if ie O ceanic F is h e ry I n v e s t ig a t io n s la b o ra to ry , proved in v a lu a b le d u rin g th e s tu d y .For E v a lu a tin g Food Components.

Three g e n e ra l system s o f a n a ly s is and methods o f e x p re ss in g r e s u l t s have evo lved from a g re a t number o f in v e s t ig a t io n s on th e food o f f i s h , b i r d s , mammals, and o th e r a n im a ls . These m ight be term ed th e n um erica l sy stem , th e freq u en cy o f o ccu rren ce system and th e v o lu m e tr ic system .

The n u m erica l system i s based s o le ly on a coun t o f organism s p re s e n t w ith eaoh food e lem ent e v a lu a te d as a p e rc e n t o f th e t o t a l number fo r a l l e le m e n ts . T h is method h as th e ten d en cy to p la c e undue em phasis on food

20

21

organ ism s w ith v ary r e s i s t a n t p a r ts so t h a t i n summing up th e food o f a number o f in d iv id u a ls , in s te a d o f g e t t in g a o ro s s - s e o t io n o f th e most r e c e n t ly o b ta in e d fo o d , a re c o rd i s o b ta in e d o f th e more d u ra b le e lem en ts o f p a s t and r e c e n t food and a f a l s e id e a o f th e food may r e s u l t . Also th e num erioa l system does n o t ta k e in to acco u n t th e s i s e o f o b je c ts and henoe conveys l i t t l e id e a as to th e r e l a t i v e im portance o f th e s e p a ra te com ponents s in o e th e n um erioa l m a jo r i ty may form bu t a sm all p ro p o r t io n o f th e fo o d . Foods t h a t have become f i n e l y b roken up oan on ly be ro u g h ly e s t im a te d by num ber. A lso , th e tim e re q u ire d fo r th e i n v e s t ig a to r t o make an a o o u ra te o o u n t, a s f o r exam ple, o f th e th o usan ds o f o rab la rv a e in th e stom ach o f a tu n a which has gorged i t s e l f on t h i s fo o d , may be p r o h ib i t iv e .

In th e freq u en cy o f o ccu rren ce system , eaoh food e lem en t i s e v a lu a te d by a p e rc e n ta g e oomputed by d iv id in g th e number o f stom aohs c o n ta in in g th e fo o d , r e g a rd le s s o f amount, by th e t o t a l number o f stomaohs exam ined. T h is p ro v id e s a rough b u t u s e fu l index to th e o v e ra l l a v a i l a b i l i t y o f the food elem en t and p erhap s i t s p a l a t a b i l i t y .

The v o lu m e tr io system i s based on a p e rc e n ta g e by bulk e v a lu a t io n .By u se o f t h i s system th e e r r o r due t o th e p resen ce o f rem nants o f p a s t fe e d in g i s reduced to a minimum. A la r g e s e r i e s o f stom aohs y ie ld s r e l i a b l e in fo rm a tio n on re o s n t fe e d in g , t h i s being th e g r e a t e s t in b u lk , w ith p a s t fe e d in g re p re s e n te d by mere t r a c e s . S is e o f in d iv id u a l food item s re c e iv e s p ro p e r r e c o g n it io n by t h i s system . W hile t h i s method i s th e b e s t o f th e t h r e e , i t has i t s d is a d v a n ta g e s . As w ith th e o th e r two t r e a tm e n ts , some s o f t bod ied organism s may lea v e no a p p re c ia b le t r a c e in th e stom aoh and th u s be u n d e rra te d in im p ortan ce . O ther e r r o r s may r e s u l t from d i f f e r e n t d ig e s t io n r a t e s fo r d i f f e r e n t fo o d s . Hess and R ainw ater

(1939) d em onstra ted t h a t f o r d i f f e r e n t k in d s o f im m ature in s e o te fe d to brook t r o u t , sm a ll s o f t -b o d ie d forms w ere d ig e s te d more r a p id ly th a n l a r g e , h e a v ily o h i t in i s e d ty p e s , K arpovich (1941) found t h a t Gammaridae w ere d ig e s te d more r a p id ly by th r e e m arine f i s h th a n were l a r g e r o r u s ta - oeane and em ail f i s h e s . From t h i s i t ap p ea rs t h a t d i f f e r e n t d ig e s t iv e r e t e s m a te r ia l ly would e f f e o t any q u a n t i t a t iv e r e s u l t e ,

Two methods o f u t i l i z i n g th e v o lu m etrlo system f o r th e e v a lu a t io n o f th e amount o f aach k in d o f food p re s e n t were proposed fcy M artin , Gensch, and £rown (1946) f o r u p land gam eblrdei

.Aggregate t o t a l volume method) th e p ero en tag e f o r each k in d o f food l e o b ta in e d by d iv id in g th e t o t a l volume o f a l l food o f eaoh k in d by th e t o t a l volume o f a l l c ro p c o n te n ts . Thev a r ia t io n in th e t o t a l volume o f food from eaoh orop in f lu e n c e sth e f i n a l r e s u l t i n d i r e c t p ro p o r t io n to t h a t volume.

2 . A ggregate p e rc e n ta g e method* p e rce n ta g e e q u iv a le n ts a reo a le u la te d fo r e ach food item w ith eaoh crop e v a lu a te d 100 p e rc e n t r e g a r d le s s o f th e volume o f i t s o o n te n ts , how ever, a l l orops l e s s th a n o n e - fo u r th f u l l were d is re g a rd e d .V a r ia t io n in th e t o t a l volume o f food p re s e n t , th e r e f o r e , does n o t in f lu e n c e th e r e s u l t e .

A lthough th e d i f f e r e n c e i n r e s u l t s o b ta in e d betw een th e s e two methods te n d s to be s m a ll , th e f i r s t has d e f i n i t e m e r i t s , one o f which i s th esa v in g o f tim e and la b o r by n o t hav ing to compute p e rce n ta g e e q u iv a le n tsf o r eaoh v o lu m e tr ic d e te rm in a tio n w ith ev ery stom ach.

T e s te r (1932) combined th e v o lu m e tr ic and th e freq ueno y o f o ccu rren ce siethods f o r a g ra p h ic r e p r e s e n ta t io n o f th e food o f th e sm all mouth b lack b a s s , lf lo ro p te ru e dolom leu. The r e l a t i v e im portance o f eaoh k ind o f food

22

23

was d em on stra ted by making a re c ta n g le w ith p e rce n ta g e volume o f a kind o f food a s th e h o r is o n ta l d im ension and th e frequ en cy o f ooourrenoe fo r th e v e r t i c a l} w here th e v e r t i c a l so a le was a r b i t r a r i l y f ix e d a t 40 p e r - c e n t o f th e h o r is o n ta l to g iv e th e volume o f food more w e ig h t. In a s t i l l d i f f e r e n t method d ev ised by W elsh (1 9 49 ), each k in d o f food wase v a lu a te d by a p e rce n ta g e r a t in g whioh was " ---- an av erag e o f th e p e rc e n to f th e t o t a l b u lk o f th e in d iv id u a l food an im als used ( in d ic a t in g abundance), and th e t o t a l number o f stom achs in whioh th e in d iv id u a l food was found i n d ic a t in g a v a i l a b i l i t y . " A lthough t h i s f i n a l averaged p ero en tag e f ig u r e a p p ea rs t o be a com bination o f d i s s im i l a r te rm s , i t may perhaps se rv e as a s im p li f ie d and u s e f u l in d ex .

T hroughout t h i s i n v e s t ig a t io n , an a tte m p t has been made to keep oom plete re c o rd s on th e c o n te n ts o f eaoh stom ach so t h a t a l l p o s s ib le in fo rm a tio n would be a v a i la b le f o r w hatever method, o r m ethods, o f a n a ly s is w ere f i n a l l y d ec id ed upon* The appendix g iv e s th e d e ta i le d r e s u l t s o f th e la b o ra to ry o b s e rv a tio n s and shows fo r eaoh food elem ent th e t o t a l number o f such organism s in a l l stom achs, th e number o f stom achs in w hich i t o c c u rre d , th e p e rc e n t freq u en cy o f ooo u rren o e , th e t o t a l volume o f suoh o rgan ism s in a l l stom aohs and th e p e rc e n t a g g re g a te t o t a l volume.

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RESULTS

G eneralThe b a s ic r e s u l t s o f t h i s s tu d y a re in c o rp o ra te d in th e app end ix *

whioh se rv e s a6 a c h e c k l i s t o f food organism s fou nd , and in ta b le I I whioh p a r t i a l l y summarized th e d a ta . From th e s e i t may be seen t h a t th e food o f th e 1097 y e l lo w fin was composed a lm ost e n t i r e l y o f f i s h (4 6 ,7% by volum e), m o llu scs (27.9% ) and c ru s ta o e a n s (24.8% ). The sm all rem ainder c o n s is te d o f p e la g ic tu n ic a to s (0 ,6% ).

Of th e f i s h , 37 fa m il ie s were re p re s e n te d , b u t o n ly 9 o f th e s e , shown in t a b l e I I , form ed more th a n one p e ro o n t each o f th e t o t a l volume o f fo o d . Those ran k in g la r g e in number, volume and frequenoy o f o ccu r­rence were th e pom fre ts (B ram idae), su rg e o n fish e s (A c an th u rid a e ), t r i g g e r f i s h e s (B & lis t id a e ) and t r u n k f i s h e s ( O s t r a o i id a e ). F ish es such as f l y in g f i s h e s (E x o o o e tid ae ), m ackerel soad (D eoapterus sp . ) and sk ip ja c k ( j&ateuwonua p e l amis ) were r e l a t i v e l y im p o rtan t in volume, beoause o f t h e i r la r g e in d iv id u a l s i z e , b u t ranked low in number and frequ en cy o f o c c u rre n c e . O ther i d e n t i f i e d f i s h e s , in c lu d in g th e snake m aokerels (G sm pylidae), and th e u n id e n t i f ie d f i s h rem ains formed n e a r ly 12 p ero en t o f th e t o t a l volum e. I t i s d o u b tfu l t h a t th e u n id e n t i f ie d rem ains con­ta in e d many specim ens o f th e n in e p r in c ip a l f a m i l ie s , w ith th e e x c e p tio n o f ju v e n i le sc o m b ro id -lik e f i s h e s .

Of th e m o llu sc s , th e sq u id were th e moat im p o r ta n t, form ing 26.2 p e rc e n t o f th e t o t a l o f 2 7 .9 n e re e n t. They were m o stly o f th e fam ily Ommastrenhidae and p ro b ab ly S y m p lec to te u th ls o u a la n ie n s i s . O ctopods, h e te ro p o d s and p te ro p o d s o c c u rre d in f r e q u e n t ly and c o n tr ib u te d l i t t l e to th e a g g re g a te t o t a l volume.

26

T ab le II* P a t t i a l summary from th e appendix showing th e m ajor c a te g o r ie s o f food organism * and th e p r in c ip a l components f o r a l l y a l lo w fin combined.

T o ta l nuraber o f organism s

% f r e q . o f o eo u r- rance

A ggregatet o t a l

volume% o f a g g re g a te

t o t a l volume

C ru s tac e a 85,140 6 6 ,9 12990.6 24.8Crab m egalops 75,875 48.2 9363.0 17.9Stom atopods 6,759 43.6 2412.7 4 .6O ther o ru a ta o e a n s 2,606 26.6 1214.9 2 .3

M ollnsoa 4 ,025 5 7 .7 . 14588.4 27 .9Squid 3,642 55 .4 13722.2 26 .2O ther m olluaos 383 1 0 .9 866.2 1 .7

T u n io a ta 240 6 .3 300.0 0 .6T a r te b r a ta (P is c e s ) 5 ,333 70 .4 24457.1 46 .7

S x o o o e tid ae( f ly i n g f i s h e s ) 23 1 .9 1740.0 3 .3

C arang idae ( j a c k s ) 53 2 .6 5800.0 11 .1B rami dae ( p o a f r e ta ) 568 16.6 2122.1 4 .1A oan th uridae

( s u rg e o n f is h e a ) 1,067 16.8 1007.2 1 .9O eapylidae (snake

m a c k e re ls ) 85 4 .6 6 24 .0 1 .2Scom bridae (tu naa

and m a c k e ra l8 ) 56 3 .6 1 4851.5 9 .3B a l ia t id a e

( t r i g g a r f i s h e s ) 367 10.5 1268.5 2 .4O s tr a e i ld a e (trunk*

f i s h e s ) 363 14.7 677.1 1 .1T e tro d o n tid a e

( p u f f e r a ) 24 1 .6 901 .0 1 .7O ther f i s h e s 288 7 .4 825.8 2 .6U nlden t. f i s h 2,439 48.2 4204.6 8 .0

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Of th e c ru s ta c e a n s , c ra b megalop« formed th e g r e a t e s t number, volume and freq u en cy o f o c c u rre n c e . Stom atopod la rv a e and p o s t la rv a e o ccu rred f r e q u e n t ly b u t d id n o t c o n t r ib u te a s muoh t o th e t o t a l volume.

In a l l , 99 c a te g o r ie s o f food organism s a re re p o r te d in th e append ix . Of th e s e , 26 o ccu rred once end 46 o ccu rred le a e th an f iv e t im e s . Of th e S3 c a te g o r ie s o c c u rr in g in more th e n o n e -h a lf o f one p e rc e n t o f th e stom aohs exam ined, 26 « e re f i s h , IS « e re c ru s ta c e a n s , 6 were m o llu sc s , and 3 were t u n i e a t e s . However, t h i s accou n ted f o r more th a n 95 p e ro e n t o f a l l o c c u rre n c e s . On th e o th e r hand, th e rem ain ing 46 c a te g o r ie s , o c c u rr in g l e s s th a n o n e -h a lf o f one p e ro e n t, accounted f o r an a g g re g a te o f l e s s th a n S p e rc e n t o f th e o c c u rre n c e s .

In g e n e ra l th e above r e s u l t s a re oom parable w ith th o s e o f o th e r i n v e s t ig a to r s in t h a t f i s h , m o llu sos and c ru s ta c e a n s , in th a t o rd e r o f d e c re a s in g im p o rtan ce , a re th e main food item s tak en by th e y e l lo w f in . S im i la r ly o th e r i n v e s t ig a to r s have found a g re a t v a r ie ty o f sp eo lea ta k e n . T here a re d i f f e r e n c e s in th e o h e o k l is t o f food organism s re p o r te d h e re and th o s e o f o th e r w orkers b u t th e s e r e f l e c t c h ie f ly th e d i f f e r e n c e in fa u n a l e lem en ts w hioh a re p re s e n t in th e a re a s in which th e f i s h w ere o au g h t. D eep-sea and r e e f f i s h e s o ccu r i n a g re a t v a r ie ty o f r e p r e s e n ta t iv e f a m il ie s in most y e l lo w f in food s tu d ie s . J u v e n ile tu n as and o th e r soom broid f i s h e s o ccu r r e g u la r ly b u t n o t i n any g re a t numbers in d ic a t in g no g re a t c o n c e n tra t io n s . L a n ts rn f is h e s (ity c to p h id a e) and f ly in g f ia h e s (H xo ooetidae) do n o t ap p ea r in th e food as f r e q u e n t ly as m ight be exp eo ted from t h e i r r e p o r te d abundance. The f re q u e n t ooourrenoe o f seem ing ly u n p a la ta b le p le e to g n a th f i s h e s ( f i a l i s t i d a e , U onaoanth idae, O s tr a o i id a e , T e tro d o n tid a e , and D io d o n tid ae ) and sm all l a r v a l c ra b s and

27

s to aa to p o d a h a re been re p o r ta d as somewhat unexpected by most o b s e rv e rs . To some e x ta n t th e food o f th e tu n as ap p ea r to be a sample o f th e fa u n a l e lem en ts w ith in a c e r t a i n a la s ran ge , Legendre (1934, 1940) and Bouxin and Legendre (1936) re p o r te d on th e fauna o f th e p e la g ic A tla n t ic Ocean by u t i l i s i n g th e organ ism s found i n th e stomach o f th e a lb a o o re , Garmo a la lu n /ra .F eed in g H a b its .

The minimum e ls e o f o rgan ism s u sed as food by th e y e llo w fin i s l e s s th a n one c e n t im e te r in le n g th w ith a d isp lacem en t volume o f l e s s th a n O.S o e . More th a n 76 p e rc e n t o f th e stomaohs examined c o n ta in ed o rg an ­ism s o f t h i s approx im ate s i z e . The r e g u la r o ccu rren ce o f l a r v a l and p o s t l a r v a l c ru s ta c e a n s and th e o c c a s io n a l re c o rd o f sm all he te ro p o d s and p te ro p o d s in d ic a te t h a t o rgan ism s o f t h i s s iz e a re n o t a c c id e n ta l lye n g u lfe d , b u t a re c a p tu re d , p ro b ab ly in re sp o n se to v i s u a l s t im u l i . T h isi s f u r t h e r s u b s ta n t ia te d by o b s e rv a t io n s made d u rin g chumming, a s y e l lo w f in w i l l pu rsue and o ap tu re b a i t f i s h o f v e ry sm all s i z e .

The maximum s iz e o f organism s used as food app ears to be dependent upon th e s iz e o f th e tu n a . Some stom aohs c o n ta in ed c a ra n g id and scom broid f i a h s s t h a t s l i g h t l y exoaeded th e stom ach le n g th and caused d is te n s io n . C e r ta in e lo n g a te f i s h e s , such es lan o e tfish es (A le p is a u r id a e ) and snake a a a k e re ls (G em pylidae) were fo ld e d two o r th r e e tim es in th e stom aoh. One y e l lo w f in ( fo rk le n g th 1358 mm) c o n ta in e d e sk ip ja c kexceed in g 400 mm. in le n g th . V e r te b ra l rem ains found a t i n t e r v a l sd u r in g th e s tu d y su g g e s t t h a t p rey o f t h i s s iz e i s n o t unoommon. The maximum s i z e o f food organism s may be o o n s ld e red ap p ro x im ate ly o n e - th ird o f th e t o t a l le n g th o f th e p re d a to r .

28

G orging may o ccu r w henever th e y e l lo w f in has th e o p p o r tu n ity to feed upon c o n c e n tra t io n s o f s u i t a b le o rg an ism s. O bservers aboard th e John ft. Manning re p o r te d c o n s id e ra b le a g g re g a tio n s Of c ra b m egalops in th e v i o i n i t y o f C hristm as Is la n d on Hay 12 and 13» 1350. The la rv a e were so numerous t h a t th e sc reen ed in ta k e o f th e h e a t exohangers f o r th e v e s s e l* s en g in es became clogged and had to be c lean ed on s e v e ra l o cca ­s io n s . Stomachs were ool lo o te d from 21 y e llo w fin (879 mm. to 1365 mm. f o rk le n g th ) c a p tu re d d u rin g t h i s p e r io d . A ll c o n ta in ed c ra b m egalops as th e p r in c ip a l food oomponent av e rag in g 1500 la rv a e (180 oo) p e r stom ach. Many f i s h w ere gorged and would r e g u r g i t a t e la r g e amounts o f o rab m egalops when lan d ed .

A d d itio n a l in fo rm a tio n co n cern in g th e fe e d in g h a b i ts and food con­sum ption o f th e y e l lo w fin may be d e r iv e d from th e d a ta . That th e sm all av e rag e volume o f 4 7 .7 oe re p re s e n te d on ly a sm all f r a c t io n o f th e d a i ly r a t i o n o f food n e c e ssa ry f o r norm al growth and developm ent became a p p a re n t d u rin .: th e e a r ly s ta g e s o f th e in v e s t ig a t io n . W ith l i t t l e o r no in fo rm a tio n con cern in g th e r a t e o f d ig e s t io n i n tunas» i t was im p o ss ib le t o a e o e r ta in what p o r t io n o f th e d a i ly r a t i o n was p re s e n t i n th e stom aoh a t any one t im e . The average w eigh t o f th e f i s h sam pled was ap p ro x im ate ly 62 pounds. Y ello w fin tu n a in t h e i r t h i r d y e a r a c co rd in g t o Moore (1951)» grow i n w e ig h t from 46 to 108 poundsl A ccording to H ia t t (1947) c a r ­n iv o ro u s f i s h shou ld oonsume ap p ro x im a te ly t e n pounds o f anim al food to grow one pound. T h erefo re» more th a n 600 pounds o f anim al food may be c o n s id e red th e annual consum ption o f th e av erag e y e l lo w fin i n i t s t h i r d y e a r . T h is e s tim a te d annual consum ption can be co n v erted in to an average

29

d a i ly r a t io n o f 740 oo p a r f i s h . The averag e stom ach c o n te n ts o f f i s h o f com parable s i z e (45 to 110 pounds) was € 1 .0 oo, somewhat g r e a t e r th a n th e averag e o f 4 7 .7 co f o r th e e n t i r e sam ple. However, th e av erage d a i ly in ta k e o f food needed to acoount fo r th e e s tim a te d grow th should be more t han te n t imes th e averag e stomach c o n te n ts found d u rin g t h i s s tu d y . T h is would in d ic a t e a v e ry ra p id r a t e o f d ig e s t io n and c o n s ta n t fe e d in g d u r in g th e day , o r th e o c c a s io n a l g org ing o f la r g e q u a n t i t i e s o f food so as to m a in ta in th e ann ual e s tim a te d q u o ta .

The e f f e c t o f s i z e o f f i s h on th e averag e stom ach c o n te n ts i s shown i n t a b le I I I . I t can be seen t h a t averag e volume o f stom ach c o n te n ts does in c re a s e w ith an in c re a s e i n s iz e o f f i s h . The m a te r ia l p re se n te d i n t h i s t a b l e iB im p o rta n t i n th e su b seq u en t e v a lu a t io n s o f th e v a r ia t io n s o f th e food e lem en ts w ith h a b i ta t and method o f f i s h in g .H a b ita t o f Prey

As p re v io u s ly n o te d , Ekman (op . c i t . ) d iv id e d th e p e la g ic rea lm in to th e n e r i t i c and o c e a n ic p ro v in c e s , d e f in e d by d ep th o f w a te r and se p a ra te d from each o th e r by th e o u te r edge o f th e c o n t in e n ta l s h e l f . The term s have b een r e ta in e d th ro u g h o u t th e p re s e n t w ork, how ever, i n th e absence o f a c h a r a c t e r i s t i c in s u la r o r c o n t in e n ta l s h e l f , th e y a re d e fin ed by fa u n a l components r a t h e r th a n by g e o g ra p h ic a l lo c a t io n . A ccording to t h i s d e s ig n a t io n th e la rv a e and ju v e n i le s o f r e e f organism s would be a s s o c ia te d w ith th e n e r i t i c p ro v in ce even though th ey o ccu rred many m ile s from lan d in ooeanio w a te r s . In l ik e m anner, la rv a e and ju v e n i le s o f t r u l y o cean ic o rgan ism s would be a s s o c ia te d w ith th e o cean ic p ro v in ce w herever found . However, o rg an ism s, such as f r e s h w a te r e e l s , (A n g u il la ) t h a t e x h ib i t d e l ib e r a te m ig ra tio n s to a n o th e r p ro v inoe f o r grow th o r

so

spawning would be a ss ig n e d to t h a t p ro v in ce f o r t h a t p a r t o f i t s l i f e o y o le . T h e re fo re , o rgan ism s a f f e c te d by wind and c u r re n t t h a t do n o t make p e r io d ic m ig ra tio n s and u s u a l ly do n o t oom plete t h e i r l i f e c y c le i n th e p ro v in ce found , w i l l be a ss ig n e d to th e p ro v ince o f o r ig in .

A ll o f th e food organ ism s found in th e stom achs o f y e llo w fin were s u r fa c e o r mid w a te r forms} none were t r u l y b e n th ic an im a ls . Some were th e J u v e n ile s and a d u l t s o f f i s h e s , s q u id s , and c ru s ta c e a n s u s u a l ly a s s o c ia te d w ith th e p e la g lo rea lm , o th e rs were l a r v a l o r p o s t l a r v a l form s o f f i s h e s and c ru s ta c e a n s u s u a l ly r e s t r i c t e d to th e sha llow w a te rs and s u b s t r a te o f th e r e e f as a d u l t s . A ll organism s may be a s s o c ia te d w ith th e n e r i t i o ( in s h o re ) p ro v in ce o r w ith th e o cean ic (o f f s h o re ) p ro ­v in c e . As m entioned p re v io u s ly , th e p e la g ic fau n a o f each p ro v in ce i s n o t c l e a r l y d e f in e d in re g io n s w ith o u t an ex tended c o n t in e n ta l o r i n s u la r s h e l f . F aunal e lem en ts c u s to m a rily a s s o c ia te d w ith one p rov ino e o r o th e r in te rm in g le th ro u g h o u t an a re a e n c i r c l in g th e em ergent la n d . The a c t i v e l y swimming organism s move f r e e l y i n t h i s a r e a , w hereas th e organism s more a t th e mercy o f th e wind and c u r r e n ts may s u b s ta n t i a l l y ex tend beyond th e a r e a , p a r t i c u l a r l y in a dosm o u r re n t d i r e c t io n . T h is over e x te n s io n in th e d i s t r i b u t i o n o f f e e b ly swimming l a r v a l and p o s t l a r v a l fo rm s, u s u a l ly r e s t r i c t e d to th e n e r i t i o p ro v in ce as a d u l t s , c o n s t i tu te s a d i f f i c u l t problem in h a b i t a t ra n g e , com plica ted by a long l a r v a l l i f e w ith m etam orphosis p o s s ib ly d e layed by a d v e rse env ironm en ta l c o n d it io n s .The i n d e f i n i t e boundary s e p a r a t in g th e n e r i t i o and th e o cean ic p ro v in ces n e c e s s i t a t e s a ohange i n co n cep t con cern in g th e fa u n a l d i s t r i b u t i o n o f an im als im m ediately su rro u n d in g i s l a n d s . The u su a l h a b i t a t o r p ro v inoe o f o r ig in has been a ss ig n e d to most organism s o r groups o f organism s

T ab le 111* V a r ia t io n in average stomach c o n te n t w ith an in c re a s e in s i c e o f f i s h .

F ork le n g th in mm

HumberAverage volume

p e r stomach i n oo

500-599 5 3 .7600-699 43 6 .2700-799 156 2 0 .0800-899 241 24.4900-999 126 4 1 .0

1000-1099 75 47 .71100-1199 116 6 1 .11200-1299 62 49.61800-1599 77 8 5 .51400-1499 52 91.51600-1599 10 8 9 .91600-1699 2 44 .2

82

l i s t e d in th e app end ix . When th e organism s o r groups o f organism s a re known to oocur i n e i t h e r p ro v in c e , b o th a re l i s t e d .

Among th e a d u l t c ru s ta c e a n s fo u nd , th e m ysida, iso p o d s , am phipods, eu p h au a id s , and p e n a iid s oocur in e i t h e r p ro v in c e , how ever, th e y oocur store f r e q u e n t ly i n th e o cean ic th a n in th e in sh o re c o l l e c t io n s . The l a r v a l and p o s t l a r v a l oruatace& na i d e n t i f i e d were a tag ea in th e l i f e c y c le o f o ra b a , lo b s te r s and a too ato po d a r e s t r i c t e d to th e n e r i t i o p ro ­v in c e aa a d u l t s . The long l a r v a l l i f e o f th e s e c ru s ta c e a n s would p erm it c o n s id e ra b le d r i f t i n g i n th e d i r e c t io n o f th e p r e v a i l in g w inds and o u r ra n ta . In any one d i r e c t io n th e numbers o c c u rr in g w i l l p ro b ab ly d ec re a se m arkedly w ith d ls ta n o e from la n d .

A ll o f th e m o llu scs i d e n t i f i e d a re a a a o o ia te d w ith th e o cean ic p ro v in o e and t h e i r f re q u e n t o ccu rren ce in th e food o f y e llo w fin caught n e a r th e r e e f i s a d d i t io n a l ev idence o f th e fa u n a l o v e rla p and th e e f f e c t o f deep o cean ic w a te r im m edia tely a d ja c e n t t o la n d . Mo p e la g ic la r v a e o f l i t t o r a l cephalopoda w ere i d e n t i f i e d among th e stomaoh con­t e n t s .

A ll members o f c e r ta in f i s h fa m il ie s a re r e s t r i c t e d t o th e ooeanio p ro v in o e ; i n o th e r f a m i l ie s th e member ap eo ie s a re found o n ly in n e r i t i o w a te r s . However, some f e m il le s have member s p e c ie s i n b o th p ro v in c e s .These g e n e ra l h a b i t a t l im i t a t i o n s a re n o t n e c e s s a r i ly th e same f o r th e l a r v a l and ju v e n i le form s as f o r th e a d u l t s . D uring t h i s s tu d y 57 fa m i l ie s o f f i s h e s w ere i d e n t i f i e d ; t a b l e IV c l a s s i f i e s th e s e acco rd in g to th e exp ec ted p ro v in o e . Ju v e n ile s o f many f i s h e s u s u a l ly a s s o e ia ta d w ith th e n e r i t i o p ro v in o e have been re p o r te d from o ffs h o re w a te rs . King and Hide, (u n p u b lish ed r e s u l t s ) found apeoim ens o f B a l ia t ld a e , H o lo o e n tr id ae , M onaoanthidae, M u llid ae , and Pom aoentridae in n ig h t l i g h t c o l le c t io n s

33

ta k e n more th a n 10 m ile s from la n d . E s s u lte o b ta in e d d u rin g t h i s s tu d y have shown t h a t many ju v e n i le s o f p le c to g n a th f ish e s« u s u a l ly a s s o c ia te d w ith th e r e e f s , have been fo u n d in th e stom aehs o f y e llo w fin ta k e n hundreds o f m ile s from la n d . A lthough th e f i s h f a m i l ie s u s u a l ly a s s o c ia te d w ith th e o cean ic p ro v in ce do n o t o ccu r abu n d an tly i n th e n e r i t i e p ro v in c e , some o cean ic s p e c ie s suoh as f ly in ^ r f is h e s , d o lp h in s (C oryphaen idae) and snake m ackere ls a re f r e q u e n t ly caugh t n e a r lan d . A lthough th e C arang idae ,S y n o dId as, B le n n iid a s , B e lo n id ae , and Bsmirhamphidae have many sp e c ie s r e s t r i c t e d to th e in s h o re w a te r s , members o f a l l f a m i l ie s have been tak e n in o f f s h o re w a te r s , in d ic a t in g a b ro ad e r d i s t r i b u t i o n . The t u n a s (Soom bridae) occupy an am b iv a len t p o s i t io n i n t h i s p a r t i c u l a r s tu d y . C e rta in s p e c ie s o f th e fa m ily a re o cean ic and o th e rs app ear to be r e s t r i c t e d , a t l e a s t d u r in g p a r t o f t h e i r l i f e c y c le , to th e in sh o re w a te rs .V a r ia t io n Between Prey and P re d a to r H a b ita ts

The h a b i t a t o f th e p re d a to r can be d e s ig n a te d by th e d ep th o f c a p tu re and th e d is ta n o e from la n d . The h a b i t a t o f th e prey c a n be a r b i t r a r i l y a s s ig n e d from knowledge o f i t s d i s t r i b u t i o n and abundance. D ata in th e append ix and t a b l e IV show th e r e s u l t s o f t h i s assignm en t to th e n e r i t i o o r o cean ic p ro v in c e , o r to both* The d a ta were com piled and a re p re ­se n te d in t a b l e V as an av erag e volume in oo p e r y e l lo w f in and r e p re s e n t an av e rag e volume f o r th o se f i s h c a p tu re d in th e p la c e d e s c r ib e d . The v a lu e s a r e n o t d i r e c t l y com parable f o r th ey r e p re s e n t l o t s o f d i f f e r e n t s i s e co m p o sitio n ta k « i by d i f f e r e n t f i s h in g m ethods. By r e f e r r in g to t a b l e I I I and f ig u r e 3 , an e s t im a tio n o f th e s e d if fe re n c e s i n average t o t a l volume and t h e i r e f f e c t upon th e com parisons can be made. However, th e c o n c lu s io n s p ro b ab ly a re r e l i a b l e as th e d if fe re n c e s i n average

T ab le IV. A ssignm ent o f in v e r t e b r a te groups and c e r ta i n f i s h f a m i l ie s , i d e n t i f i e d d u rin g t h i s i n v e s t ig a t io n , to th e ex p ec ted o r r e p o r te d h a b i t a t .

N e r i t io O ceanic Both

C ru s tac e a n s C ru staceana F ish e sN sphropsidaa M ysidacea Synodidaea l in u r id a e Isopoda B len n iid ae

Crab aeg a lo p a Araphipoda B elonidaeStom atopods Euphaua1daeea Hemlrhamphl dee

F is h e s Shrimps SoomhridaeA ulostom idae F ish es Car an £ idaeS yngnath ida# S te rn o p ty c h id a eH o lo e e n tr id a e SudidaeS phyraen idae A le p ia a u r ld a ePolynem idae M yotophidaaP ria c a n th id a e E xoooatldaaL u tia n id a e M acruridaeC hae tod o n tidae L ophotidaePPm flcentridae BramidaaL abrldae C oryphaenidaeA can th u rid ae G eapylidaeB oth idae MoraeidaeM onaoanthidae EoheneidaeO s tra o ild a e M olidaeT e tro d o n tid a eD io d o n tid ae

s s

t o t a l volume would e f f e c t th e v a lu e s o n ly s l i g h t l y . From t h i s ta b le i t can be seen t h a t in sh o re s u r fa c e y e llo w fin u se th r e e tLines as much n e r i t i o food as o ce a n io , in s h o re su b su rfa ce o n e -h a lf as muoh, and o f f ­sh o re su b su rfao e o n e -e ig h th as much. For in sh o re su rfa o e y e l lo w f in , n e a r ly o n e -h a lf o f a l l fo o d , c l a s s i f i e d by p ro v in c e , was composed o f n e r i t i o o ru e ta o e a n s , Ooeanio c ru s ta c e a n s do n o t ap o ea r im p o rta n t in any g rouo j how ever, th e s e d a ta do in d ic a te t h e t th e y a r e n o t c o n c e n tra te d n e a r la n d . In a d d i t io n to th e in s h o re -o f f s h o re h a b i t a t r e l a t i o n s h i p , th e d a ta In t a b l e V shows t h e e f f e c t o f a v e r t i c a l oomponent. N e r it io c ru s ta c e a n s and f i s h ap p ea r more abundant in th e su rfa o e w a te rs and o cean io f i s h and m o llu scs more abundan t in th e d ep th s .V a r ia t io n o f Food E lem ents w ith Method o f C apture

A ll f i s h oaught w ith in te n m iles o f land were used to show th e e f f e c t o f v a r i a t i o n o f food w ith method o f o a p tu re . As n e a r ly a l l t r o l l - cau g h t f i s h , and a l l p o le and l in e -o a u g h t f i s h w ere tak e n w ith in te n m ile s o f la n d , o n ly th o se lo n g lin e -c a u g h t f i s h from w ith in t h a t d is ta n c e oould be used f o r oom parison. The r e s u l t s a re p re se n te d in t a b l e VI and show th e fo llo w in g !

1 . T ro l l- c a u g h t f i s h had more th a n tw ic e a s many m ackerel send, f l y in g f i s h e s and tu n a s , b u t on ly h a l f as many sq u id s and su rg eo n fi8 h e6 as p o le and l in e -c a u g h t f i s h .

2 . No m ackere l scads and few er tu n a s and su rg e o n flsh e s in th e su b su rfa c e f i s h th an in th e su rfa o e f i s h .

S. Mors p o m fre ts , t r i g g e r f i s h , p u f f e r s and f ly in g f i s h e s in th e food o f th e su b su rfa o e f i s h .

4 . Squid and stom atopode more abundant in su b su rfa c e th a n su rfa c e -c a u g h t f i s h .

5. C rab m egalops much more abundant in su rfa o e -o a u g h t f i s h .

36

T able V. V a r ia t io n betw een p ray and p re d a to r h a b i t a t s as shown by th e l o c a l i t y o f c a p tu re and th e exp ec ted p rov ince o f th e food o rg an ism s. (V alues used f o r com parative im p ortance have been c a lc u la te d aa averag e volume In oo p e r f i s h . )

M e ritic OceanicC ru stacean s F is h C ru staceans F ish M olluscs

In sh o re (0 -9 m i .) S u rfa ce

(n . 776)23 .37 13.91 .9 6 3 .26 7 .76

S u b su rface (n z 70) 1 0 .1 0 7.66 .11 7 .6 7 25 .65

O ffsh o re (more th a n 10 m i . ) S u b su rface

(n = 241) 1.66 6 .69 .6 5 .9.91 37.81

37

The d if f e r e n c e s i n 1 may be due to th e d if f e r e n c e s in h a b i ts o r se a so n . F ish caugh t by t r o l l i n g d u rin g th e s e c r u is e s d id n o t a p p e a r to be c o n c e n tra te d in sch o o ls w hereas p o le and l in e -c a u g h t f i s h w ere. As 271 o f th e 305 p o le and l in e - c a u g h t f i s h w ere ta k e n d u rin g one c ru is e in June 1951. what d i f f e r e n c e s may app ear m ight w e ll be due to th e tem poral change r a t h e r th an to f i s h in g m ethod.

The d i f f e r e n c e s in 2 , 3 , 4 . and 5 a re p ro bab ly due t o bo th v e r t i c a l and in s h o re -o f f s h o re d i s t r i b u t i o n o f th e food o rgan ism s. M ackerel scad , t u n a s , su rg e o n fie h e s and c ra b m egalops ocour more ab u n d an tly in th e s u r fa c e w a te rs and , w ith th e p o s s ib le e x c e p tio n o f some tu n a s , a r e p ro b a b ly a s s o c ia te d w ith th e n e r i t i c p ro v in c e . Ib m fre ts and sq u id a re a s s o c ia te d w ith th e deep er w a te rs o f th e o cean ic p ro v in ce and t h e i r o cc u rre n c e in th e food o f su b su rfa c e f i s h i s e x p ec ted . The f ly in g f i s h e s . u s u a l ly found i n th e s u r fa c e w a te rs o f th e o cean ic p ro v in c e , o ccu rred i n o n ly one stomach o f s u b s u r fa c e - in s h o re y e l lo w f in , T r ig g e r f is h e s , p u f f e r s and stom atopods a re n e r i t i c organism s in t im a te ly a s s o c ia te d w ith th e r e o f and t h e i r g r e a t e r abundance in th e deep er w a te rs a lo n g th e r e e f 's edge i s n o t u n ex p ec ted .V a r ia t io n o f Food E lem ents w ith D is ta n c e from Land.

Only y e llo w fin cau g h t by 1o n g lin e f i s h in g w ere ta k e n , to any e x te n t ,i n th e o f f s h o re w a te r s . The r e s u l t s o f th e v a r ia t io n o f food e lem en ts w ith d is ta n o e from lan d i s shown in t a b le VII* The fo llo w in g changesappeared to be most im p o rta n t t o th e p re s e n t study*

1* Fbm frets (B ram idae) oocu rred th ro u g h o u t th e e n t i r e d is ta n o e b u t f e l l o f f r a p id ly beyond 200 m ile s ,

2 . T r ig g e r f is h e s ( B a l i s t i d a e ) , su rg e o n fish e s (A c an th u rid a e ) , and p u f f e r s (T e tro d o n tid a e ) , w ere more abundant near lan d b u t o cc u rre d in o f f s h o re w aters*

58

T ab le VI, V a r ia t io n in food components w ith method o f e a p tu re (and/or d e p th ) f o r f i s h c a p tu red w ith in te n m ile s o f la n d . Valuee used f o r com para tiv e im portance have been o a lo u la te d a s average volume in oo p er f i s h .

S u rface S ub su rfaceT r o l l in g P, k L. L ongline

C ru stacean sCrab m egalops 10.43 13.56 .76Stom atopods 2 .01 2 .67 7 .6 0O ther o ru s ta o e an s l . U .4 7 4 .84

CephalopodsSquid 2 .77 6 .94 24.06A rgonauts .06 .34 .79Octopods .0 4 .33 .26

P isc e sC arang ldae 7 .3 0 4 .62 00Scom bridae 4 .78 1 .0 9 .1 7B raa id ae .0 9 .08 2 .67S xo oo etid ae 1 .8 0 .89 3 .2 9 *B a l i s t ld a e .23 1.48 3 .09A can th u ridae .88 1 .64 .44T e tro d o n tid a e .6 0 .0 1 3 .43O s tra o i id a e .3 4 .2 2 .4 9

from a s in g le o cc u rre n c e

39

3« M egalops, stom atopods and o th e r c ru s ta c e a n s d ec reased m arkedly w ith d is ta n c e from la n d .

The d ec re a se i n pom fre t abundance beyond 200 m ile s from lan d i s u nex p ec ted and u n e x p la in a b le . Very l i t t l e i s known con cern ing th e d i s ­t r i b u t i o n o f t h i s fam ily and n o th in g i s re p o r te d in th e l i t e r a t u r e to a c co u n t fo r t h i s change. The g r e a t e r abundance o f n e r i t i o organism s n ea r sh o re and th e d e c re a s in g numbers w ith d is ta n c e from land i s to be ex p ec ted . A ll a e g a lo p a , stom ato pod s, t r i g g e r f i s h e s , a u rg e o n f ish e e , p u f f e r s and t r n n k f i s h o s w ere l a r v a l o r J u v e n ile form a, a s s o c ia te d w ith th e r e e f a s a d u l t s . These form s ap p ea r to be much more w id e ly d i s t r i b u t e d th a n has bean p re v io u s ly r e p o r te d . However, th e y a re p ro b ab ly more abundant n ea r th e r e e f as i s diown by th e volumes found f o r a l l excep t th e l a s t named fa m ily o f f i s h e s , th e t r u n k f i s h e a .

As n o ted i n t a b l e VII s e v e r a l v a lu e s fo r th e C arang id ae , Scom bridae and S xo oo e tld ae came from a s in g le o ccu rren ce . The v a lu e o f 9 .44 f o r th e Scom bridae from y e l lo w f in ta k e n betw een 200-499 m iles i s p a r t i c u l a r l y i n t e r e s t i n g . Four y e llo w fin in t h a t group c o n ta in ed fo u r sm all tu n a s , two b ig -e y e d tu n a ( P arathunnns s i b i ) , one s k ip ja c k and one y e l lo w f in .The o cc u rre n c e o f th e l a s t named specim en in o cean ic w a te rs more th an 200 m ile s from lan d i s p a r t i c u l a r l y im p o rtan t to th e p re s e n t s tu d y . There i s room f o r doubt in r e s p e o t to th e i d e n t i f i c a t i o n o f th e y e llo w fin tu n a , a s * n ly r e l a t i v e l y m inor c h a r a o te r i s t i o s d i f f e r e n t i a t e th e sp e c ie s from th e b ig -e y e d tu n a .V a r ia t io n in P iu m a l F eed ing A c t iv i ty .

Knowledge o f d iu rn a l fe e d in g a c t i v i t y may be o f c o n s id e ra b le im p o rtan ce to th e f i s h e r y and to f u tu r e i n v e s t ig a t io n s . C e r ta in a s p e c ts

T able V II . V a r ia t io n in food components w ith d is ta n c e from lan d f o r f i s h c a p tu red by lo n g l in e g e a r .Value« u sed f o r com p ara tiv e im p ortan ce have been c a lc u la te d a s averag e volume in oc. p e r f i s h .

0 - 9m ile s

n - 7010 - 24

m ile s n - 27

26 - 49 s t i le sf l t 12

50 - 99 s t i le s n ■ 27

100 - 199 s t i le sn s 37

200 - 499 m ile s

n a 124o v e r 500

m ile sn s 14

FISHC arang idae 7 .7 4 *Soombrldae .1 7 .2 2 28 .15* 7 .0 3 * 9.44Bramldaa 2 .67 2 .2 0 S. 50 12.85 6 .1 9 .5 3 .1 4E xoooetidae 3 .2 9 * 5 .7 0 1 .4 9B a l ie t id a e 3 .0 9 8 .06 5 .5 0 1 .15 .41 1 .06A oanthuridae .44 1 .8 9 .7 5 .0 4 .06T e tro d o n tid a e 3 .43 3 .7 4 .1 5 .4 3O a tra o iid a e .4 9 1 .06 1 .25 .1 6 2.32 .3 4 3 .5 7

CKPiULOPODSSquid 24.06 56.37 35.50 24.78 30 .59 3 6 .93 23.71A rgonauts .7 9 2 .26Ootopoda .26 .0 4 1 .3 3 .3 2 .4 1 .14

CRUSTACEAUegalops .76 8 .5 6 .0 2 .1 6 .2 7S to oa topo ds 7 .6 0 3 .76 .25 .1 9 .0 8 .07O ther C ru s tac e a 4 .8 4 1 .48 7 .33 .39 .1 6 .3 9 .2 1

*Front a s in g le o ccu rren ce

41

o f th e v a r i a t io n i n fe e d in g a c t i v i t y can be ehown by th e r e s u l t s o f t h e p r e s e n t s tu d y . The aotu& l tim e o f c a p tu re was reco rded f o r 656 f i s h cau g h t on th e s u r fa c e by t r o l l i n g o r p o le and l in e f i s h i n g , lo n g lin e f i s h were ta k e n aboard th e v e e s e l a t t h e d o s e o f th e f i s h in g day and th e a c tu a l t i n e o f "hook ing1* was n o t known. T ab le V III g iv e s th e number, a v e rag e volume i n co , and th e number o f empty stom achs f o r th e f i s h cau g h t d u rin g e i t h e r th e m orning o r th e a f te rn o o n p e r io d o f th e day. The s i g n i f i o a n t l y l a r g e r av e rag e volumes among th e f i s h oaught d u rin g th e a f te rn o o n in d ic a te t h a t th e f i s h f eed m o stly d u rin g th e hours o f day­l i g h t . T h is i s c o n tra ry to th e o o n o lu sio n o f Ban (1941) who s t a t e s t h a t " ju d g in g from th e tim e a t w hich th e f i s h ware ta k o i and th e p ro g re ss o f d ig e s t io n i t ap p ea rs t h a t th e f i s h feed s t n ig h t ." However, he gave no f u r t h e r in fo rm a tio n ooooern ing th e a c tu a l tim e o f o ap tu re and th e r e f o r e , i t I s im p o ss ib le to examine h i s c o n c lu s io n c r i t i c a l l y .

T r o l l in g was oonduotsd o c c a s io n a l ly d u rin g th s hours o f d a rk n e ss , b u t no y e l lo w f in w ere ta k e n . T h is in f re q u e n t n o c tu rn a l t r o l l i n g was done d u rin g p assag e from one i s l a n d , o r i s l a n d group to a n o th e r .D uring th e two y e a rs o f t h i s I n v e s t ig a t io n o n ly s ix y e l lo w fin were c a o tu re d more th a n 25 m ile s from lan d by day t r o l l i n g . T h e re fo re , th e f a o t t h a t no y e l lo w f in were caugh t d u rin g n ig h t t r o l l i n g in an a re a where o n ly s ix f i s h were c au g h t d u r in g o o n s ta n t day t r o l l i n g g iv e s no r e l i a b l e in fo rm a tio n con cern in g th e n o c tu rn a l h a b i t s o f th e s p e o ie s .V a r ia t io n i n Kind o f Food E aten w ith S i t e o f F ish

B seause a l l s u rfa c e -c a u g h t f i s h were ta k m w ith in te n m ile s o f land t h i s group was used t o s tu d y th e v a r i a t i o n o f food e lem ents w ith s i t e o f f i s h . Two p r in c ip a l ohanges a re shown In t a b l e IX | f i r s t , a marked d e c re a se i n c ru s ta c e a n s w ith an in o re a s e in y e l lo w f in s i c e , and seco n d ly ,

42

T ab le T i l l . V a r ia t io n in average stom ach con ten ts w ith morning o r a f te rn o o n c a p tu re .

M orning A fternoon

T ro l l in gHumber 223 138Average volume

p e r a tooaoh 27 .1 oo 4 1 .5 ooHumber o f etomaohs

empty 23 6P ero en t o f t o t a l

empty 10.3 4 .3Pole and L ine

lum ber 175 120Average volume

p e r atam aoh 2 7 .4 oo 65*6 ccNumber o f storaaoha

empty 51 8P e rc e n t o f t o t a l

empty 29 .1 6 .7T o ta l

Hum be r 398 268Average volume p e r

stom ach 27 .2 cc 5 2 .5 ooHumber o f stom achs

empty 74 14P ero en t o f t o t a l

empty 18.6 5 .4

)

43

a s u b s ta n t i a l in c re a s e i n fo ra g e f i s h e s w ith an in c re a s e in y e l lo w f in s i z e . The r e s u l t s g iv en i n t a b l e I I I showed th a t th e r e is an in c re a s e i n a v e ra g e volume w ith an in c re a s e in s i z e o f f ish * Some in c re a s e would be ex p ec ted in any component f o r i t to m a in ta in th e same p ro p o r tio n o f t h e food th ro u g h o u t th e a ls o ran g e , T h e re fo re , th e r e s u l t s shown in t a b l e IX a re s l i g h t l y d i s t o r t e d f o r th e in c re a s in g averag e volume w ith s i z e o f f l a h m inim ize th e d e c re a s in g av erag e volume f o r th e o ru s tao ean s and e x a g g e ra te th e in c r e a s in g av erag e volume f o r th e fo ra g e f i s h e s .From t h i s t a b l e i t can be seen t h a t sm all c ru s ta c e a n s occur in th e food o f y e l lo w f in In a l l s iz o a b u t become c o n s id e ra b ly l e s s im p o r ta n t to th e l a r g e r f i s h . A lthough th e l a r g e r f i s h e a t many o f th e sm all organism s w hioh a r e a ls o e a te n by th e sm a lle r f i s h , th e s m a l le r f i s h f in d i t m eo h an io a lly im p o ss ib le to e n g u lf th e l a r g e r fo ra g e f i s h e s and sq u id s . The in c re a s e in av e rag e volume o f fo ra g e f i s h e s w ith s i t e o f y e l lo w fin i s p a r t i a l l y due to th e f a c t t h a t l a r g e p ray a re a u to m a tic a lly excluded from th e food o f th e s m a lle r tu n a .

44

T ab le IX. V a r ia t io n in th e m ajor c a te g o r ie s o f food organism s w ith method o f o a p tu re and s iz e o f f i s h . A ll f i e h ta k e n by t r o l l i n g and p o le and l in e f i s h in g w ith in t e n m ile s o f la n d . Average volume in oo fo r eaoh e ls e g roup .

Humber C rustao eans Squid P is h

T r o l l in g600-999 mm 317 9.2 2 .4 8 .3

1000-1299 am 139 2 4 .3 3 .9 30 .21500 mm A over 14 4 .7 4 .9 187.4

B ale and L ine600-999 mm 227 18.4 6 .1 8 .3

1000-1299 mm 66 15.2 8 .6 1 7 .21300 omt A o ver 12 2 .8 5 .6 69.2

T o ta l600-999 mm 544 13.1 4 .0 8 .3

1000-1299 o s 205 20.7 6 .5 2 6 .01300 mm A o ver 26 3 .8 6 .2 128.2

45

DISCUSSION

T h is s tu d y g iv e s q u a n t i t a t iv e e s t im a te s o f th e v a r io u s food organism s e a te n by y e l lo w f in tu n a , to g e th e r w ith in fo rm a tio n on t h e i r v a r i a t io n w ith r e s p e c t t o method o f c a p tu re , p la c e o f o a p tu re in c lu d in g d is ta n o e from lan d and d e p th , s iz e o f f i s h , and tim e o f day. I t a ls o in c lu d e s a s tu d y o f v a r i a t io n in th e q u a n t i t i e s o f th e s e food organism s when c l a s s i f i e d a c c o rd in g t o t h e i r normal o r expec ted h a b i t a t —n e r i t i c o r o o ean io . I t rem ains to c o n s id e r any r e l a t i o n s h i p w hich may e x i s t betw een th e d i s t r i b u ­t i o n and abundance o f th e tu n a and t h a t o f th e food o rgan ism s.

Catch r e p o r t s f o r th e specim ens ta k e n by th e th r e e methods o f f i s h in g have shown ( a ) t h a t no y e l lo w f in w eighing l e s s th a n 40 pounds were oaught by lo n g lin e g e a r , th e o n ly method o f su b su rfa c e f i s h in g , (b ) t h a t v e ry few y e l lo w f in w ere ta k e n a t th e s u r fa c e more th a n t e n m iles from lan d as compared w ith la r g e numbers ta k e n a t th e a u rfa c e c lo se t o lan d and l a r g e numbers ta k e n below th e s u r fa c e away from la n d , (o ) t h a t g r e a te r c o n c e n tra t io n s o f sm all and m edium -sised f i s h o ccu rred n e a r lan d as com­p a re d w ith away from la n d .

The y e l lo w f in , l i k e many o th e r s p e c ie s o f f i s h , does n o t r e s t r i c t i t s d i e t to s p e c i f i c k in d s o f food b u t u t i l i s e s a g re a t v a r ie ty o f o rg an ism s. T h is f a c t , to g e th e r w ith a la c k o f knowledge o f th e p re c is e abundance o f th e food organism s w hich were p re s e n t in th e w a te r a t th e tim e th e tu n a w ere o aug h t, make i t d i f f i c u l t t o draw d e f in i t e c o n c lu s io n s .

P rey s i s e , average stom ach o o n te n ts , and th e r e l a t i o n o f th e s e f a c to r s to th e food demands and th e p o te n t i a l stom ach c a p a c i t i e s in d ic a te t h a t th e m a jo r i ty o f th e y e llo w fin examined d u rin g t h i s s tu d y were m in im ally fe d .To o b ta in th e d a i ly req u irem en t n e c e ssa ry fo r normal grow th, th e f i s h m ust c o n s ta n t ly se a rc h fo r food—a t l e a s t d u rin g th e day tim e. Food, th e n .

may w e l l be a p rim ary f a c t o r i n e f f e c t in g th e d i s t r i b u t i o n and abundance o f t h i s s p e e ie s .

The l a r g e r th e f ia h , th e l a r g e r th e e ls e o f t h e food o rganism s which i t may e a t . However, o n ly a few la rg e organism s were found in th e stom ach c o n te n ts o f th e l a r g e r f i s h caugh t w e ll below th e s u r fa c e in lo n g lin e f i s h in g . The m a jo r ity o f th e organism s were sm all enough to be c o n s id e red s u i t a b le food f o r th e sm a lle r s u r fa c e -c a u g h t f i s h . T h e re fo re , th e absenoe o f sm a ll y e l lo w f ln in th e su b su rfa c e lo n g lin e ca tc h i s n o t n e o e s s a r i ly due to th e s i z e o f th e food organism s p re s e n t a t th o se l e v e l s .

The food organism s found i n th e stom ach c o n te n ts o f la r g e y e llo w fln cau g h t by lo n g lin e f i s h in g in th e o f fs h o re w ate rs were p r in c ip a l ly squ id and d e e p -se a f i s h . These food organism s a re a s s o c ia te d w ith th e m iddle d ep th s and in f r e q u e n t ly o ccu r d u r in g th e d ay i n th e s u r fa c e la y e r s o f th e o cean . T h e re fo re I t seems l i k e l y t h a t d u rin g th e day tim e th e la r g e y e l lo w f ln w ere a t t r a c t e d to th e su b eu rfao e la y e r s by t h e i r p re se n c e .

I t h as been shown t h a t y e l lo w f ln caugh t c lo se to th e i s la n d s and r e e f s oonsumed more n e r i t i c th a n o cean ic o rgan ism s, and t h a t th e r e was a g r a d ie n t i n th e p ro p o r t io n o f n e r i t i c to o cean ic form s w ith in c re a s in g d is ta n c e from la n d . M oreover i t was shown t h a t th e sm a lle r s u rfa c e fe e d in g f i s h consumed more sm a ll c ru s ta c e a n s th a n th e l a r g e r f i s h w hich w ere ta k e n i n th e su b su rfa c e w a te rs . Presum ing t h a t th e sm all y e llo w fln a re con fined to th e s u rfa c e w a te rs as in d ic a te d by th e lo n g lin e c a tc h re c o rd s and i t a p p e a rs th e r e i s a g r e a ta r o o n o e n tra tio n o f s u r fa c e food organism s c lo se t o th e i s l a n d s . I t fo llo w s t h a t th e sm a ll y e llo w fln m ight c o n c e n tra te in t h e v i c i n i t y o f la n d . I f t h i s i s s o , i t m ight p a r t l y e x p la in t h e i r absenoe from th e s u r fa c e la y e r s o f th e open ocean , a lth o u g h th e accu m u la tio n around th e i s la n d s does n o t seem la r g e enough to aocoun t f o r th e e n t i r e p op u la ­t i o n o f sm a ll y e llo w fln w hich m ust be p re s e n t somewhere in th e a re a .

46

47

R e g a rd le ss o f w he th er th e n e r i t i o fa u n a g en e ra te d in th e v i c i n i t y o f th e I s la n d s and r e e f s a t t r a c t s sm all tu n a to th e in sh o re w a te rs , i t i s c l e a r t h a t th e n e r i t i o fauna does p ro v id e an im p o rta n t component in th e d i e t o f th e y e l lo w f in , th e in f lu e n c e o f which ex tends su ch f a r t h e r from sh o re th a n m ight have been a n t i c ip a te d . Thus, i t i s presum ptuous and s p e o i f i o a l l y i n c o r r e c t t o d iv id e th e p e la g ic re g io n in to two d i s t i n c t and s e p a r a te p ro v in c e s , each w ith i t s own fa u n a l e lem en ts . T here i s con­s id e r a b le o v e rla p p in g o f th e fa u n a l e le m e n ts , some an im als m ig ra tin g o r s t r a y in g from one p ro v in ce t o th e o th e r , o th e r s in h a b i t in g b o th th ro u g h ­o u t t h e i r l i f e c y c le , and s t i l l o th e r s in h a b i t in g one p rov inoe d u rin g p a r t o f t h e i r l i f e c y c le and th e o th e r d u r in g th e rem ain ing p o r t io n .

In c o n c lu s io n i t a p p ea rs t h a t th e d i s t r i b u t i o n o f th e y e llo w fin o f v a r io u s s i z e s i s in f lu e n c e d by th e abundance o f c e r ta in food o rgan ism s.The o o cu rren oe o f la r g e y e l lo w f in i n su b su rfa c e ooeanio w a te r i s p ro b ab ly r e l a t e d to th e p re se n c e o f sq u id and d ee p -se a f i s h e s . The sm a lle r y e llo w ­f i n may be a t t r a o te d in sh o re by th e g r e a te r abundance o f su rfa o e food o rg an ism s—s p e c i f i c a l l y p e la g ic la rv a e o f c ru s ta c e a n s and th e ju v e n i le s o f r e e f f i s h e s . A lthough organism s o f r e e f o r ig in o ccu rred as food th ro u g h o u t th e e n t i r e r e g io n o f th e s tu d y , t h e i r in f lu e n o e appeared to d im in ish m arkedly w ith d is ta n c e from la n d . However, i t seems l i k e l y t h a t th e a v a i l a b i l i t y o f foo d i s b u t one o f many in t e r a c t in g f a c to r s w hich j o i n t l y govern th e d i s t r i b u t i o n and abundance o f th e y e l lo w f in . A con­s i d e r a t i o n o f o th e r p o s s ib le f a c to r s i s beyond th e scope o f t h i s p ap e r.

CONCLUSIONS

In g e n e ra l th e food o f th e y e llo w fin c o n s is te d o f f i s h (4 6 .7>*), m o llusee ( 2 7 .! # ) , and o ru a tao ean a (2 4 .8 ^ ) .A lthough a g re a t v a r ie ty o f f i a h were found , th e p o m fre ts , su rg eo n - f i a h e s , t r i g g e r f i a h e e , t r u n k f i s h e s , snake m a c k e re ls , f ly in g f ia h e a , s k ip ja c k , and m ackerel aoad w ere moat Im po rtan t i n numbera, freq u en cy o f o ee u rre n o e , and a g g re g a te t o t a l volume.N early a l l m o llueca w ere aqu lda and p ro bab ly were m oatly S y m p le e to te u th is o u a la n ie n a la .Crab m egalopa, ju v e n i le stom atopods, and o th e r l a r v a l o ru a tao ean a o o cu rred f r e q u e n t ly and c o n tr ib u te d a u b a ta n t i a l ly to th e ag g reg a te t o t a l volum e.The r e a u l t s o f th e p re s e n t s tu d y ag ree in g e n e ra l w ith p rev io ua in v e s t ig a t io n s . V a r ia t io n s r e s u l t from fa u n a l d i f f e r e n c e s among th e a re a s from whioh th e y e llo w fin were cau g h t.P rey w ith a d isp la ce m e n t volume o f l e s s t h a n 0 .5 oo were oommon among th e food o rgan ism s.A lthough maximum le n g th o f p rey app ears t o be o n e - th ir d o f th e p r e d a to r , s le n d e r f i s h e s may be used as food even when equal to o r g r e a t e r th a n th e y e llo w fin * a le n g th .G orging may cu o u r w henever s u i t a b le organism s a re abundant.The averag e volume o f th e stomach c o n te n ts p ro b ab ly would n o t s u f f i c e f o r th e d a i ly r a t io n so a s to p erm it norm al grow th and developm ent. C o n stan t fe e d in g d u rin g th e day and a v ery ra p id r a t e o f d ig e a t io n ap p ea rs t o be th e most l i k e l y e x p la n a tio n .The av e rag e volume o f stom ach c o n ten ts in o re a s e s w ith an in o re a s e in th e average s i s e o f y e l lo w f in .

49

1 1 . N e r i t ic o rgan ism s u sed as food were m ost abundant n s a r sho re and on th e s u rfa o e , l e s s abundant n e a r shore i n th e d e p th s , and l e a s t abundant o f fs h o re in th e d e p th s .

12. Ooeanic organ ism s u sed as food were moat abundant o f fs h o re in th e d e p th s , l e s s abundan t in sh o re in th e d e p th s , and l e a s t abundan t in s h o re a t th e s u r f a c e .

13. S o l i t a r y y e l lo w f in ta k e n by t r o l l i n g fe d more on s k ip ja c k , f l y in g - f i s h e s , and m ackerel scad and l e s s on sq u id and su rg e o n fish e s th a n do sc h o o lin g y e l lo w f in caugh t by p o le and l in e f i s h in g .

14* S u rfao e caugh t y e l lo w fin fe d on food o rgan ism s a s s o c ia te d w ith th e su rfa o e in sh o re w a te rs and th e su b s u rfa c e caugh t y e l lo w fin fed l a r g e ly on e i t h e r r e e f organ ism s a s s o c ia te d w ith th e bottom or ooean ic o rg an ism s.

15. The food o f th e y e l lo w f in co n ta in ed l e s s n e r i t i c organism s and more o oean ic o rganism s as th e d is ta n c e from la n d in c re a s e d .

16. The o ccu rren ce o f n e r i t i c organism s was n o tic e d in th e extrem e o ffs h o re w a te rs b u t had g r e a t ly le s s e n e d in im portance as foo d .

17. F eed ing p ro b ab ly ocours d u r in g d a y l ig h t h o u rs ; how ever, i f fao d in g o ccu rs a t n ig h t i t does so to a g r e a t ly d im in ished e x te n t .

18 . Sm all y e l lo w fin feed more h e a v ily on o ru s tao ean a and l a s s on f i s h th a n do l a r g e y e l lo w f in .

19. Sm all y e l l o w f i n ( l e s s t h a n 4 0 pounds) a p p e a r to be r e s t r i c t e d to th e su rfa o e w a te rs and a re more abundan t in th e im m ediate v io i n i t y o f la n d w here J u v e n ile r e e f f i s h e s and c ru s ta c e a n s a re r e a d i ly a v a i la b le a s fo o d .

20 . T here a re v e ry few marked d if f e r e n c e s i n th e food o f th e la r g e and sm a ll y e l lo w f in . Large p rey a re m e c h a n ic a lly exc lud ed from th e d ie t

50

o f sm all y e l lo w f in , Sm all c ru s ta c e a n s a re e a te n as food by th e la r g e y e l lo w fin b u t a re r e l a t i v e l y u n im p o rtan t.

21 . Food organ ism s and t h e i r abundance p ro b ab ly in f lu e n c e th e abundanceo f y e l lo w fin to 6ome e x te n t and may oau66 a c o n c e n tra t io n o f th e a m a lle r y e llo w fin in th e w a te rs im m ediately »unrounding is la n d s and r e e f s .

22 . A m u l t i p l i c i t y o f f a c to r s , in c lu d in g fo o d , p ro b ab ly e f f e c t and c o n tro l th e d i s t r i b u t i o n o f th e y e llo w fin o f a l l s i t e s .

51

APPENDII

L i s t o f o rgan isa is found in th e stomach c o n te n ts o f 1097 y e llo w fin tu n a o ap tu red in th e o e n t r a l P a o if io r e g io n . For each food elem ent th e r e i s g iv en th e t o t a l number o c c u r r in g , th e number o f stomaohs in w h io h e a o h o o o u rre d , th e p e rc e n t freq u en cy o cc u rre n c e , th e a g g re g a te t o t a l volume and th e p e rc e n t a g g re g a te t o t a l volume, when l / lO o f 1 p e rc e n t o r g r e a te r .The l e t t e r s H f o r n e r i t i o , 0 f o r o c e a n ic , and B f o r b o th p ro v in ces a re used to d e s ig n a te th e expeoted h a b i ta t f o r each organism o r group o f o rg an ism s.

Totalnumber oforganisms

Sumber o f stom aohs i n e h i oh o cc u rre d

AKTHROPODA C ru stacea

tfysldaoeaO plophoridae

Oplophorus f o l ia c e u sU n id e n tif ie d rnyside

Zsopoda Amphipoda

H y p eriid ae O xycephalidae Gemmaridae C a l l lo p i id a e U n id e n tif ie d amphipods

S u phau siacea Euphausidae

E uphauaia sp .

8 5 ,140

20

27

25111

2

202

55

734

115

80411

50

P ercen t f r e ­quency o f o ccu rren ce

A ggregatet o t a lvolume

P ero en ta g g re g a te

t o t a lvolume

P rov ince

6 6 .9 12990.6 24.8

.1 105 .0 .2 0.1 .1 0.5 1 .2 0

7 .3 7 8 .0 .2 0.4 2 .3 0.1 • 2 0.1 .5 0

4 .6 5 8 .3 .1 0

.5 6 .4 0

cnro

T o ta l number o f o rgan ism s

Humber o f stom achs i n w hich o cc u rre d

P e rc e n t f r e ­quency o f o ccu rren ce

A ggregatet o t a lvolume

P e ro e a ta g g re g a te

t o t a lvolume

P rov i nee

U n id e n ti f ie d eupheueide 6 Z .2 2 .0 0Decapods

P enaeidaeU etapenaeus sp . 38 4 .4 7 0 .0 .1 8

U n id e n ti f ie d shrim p 999 81 7 .4 288.8 .6 BN ephropeidae

Enoplometopue ap . p o e t la rv a e 905 95 8 .7 2 95 .0 .6 H

P a lin u r id a eP a n u liru s sp*

phyllosom a la rv a e 7 5 .5 2 .8 Hp u e ru lu e p o e t la rv a e 18 1Z 1 .1 1 8 .0 H

B raohyurans Crab soeae 2 2 .2 1 .0 HCrab mogalops 75,875 529 48 .2 9565 .0 17.9 I

P agu ridae 1 1 .1 • S H

Number o f stomach* i n w hich o cc u rre d

Stom atopods S q u il l Id a *

S q u i l l a sp . a l imaP g e u d o sq u i l la o i l l a t a

m onodactylus s ta g eP a e u d o sq u illa o c u la ta

e r io h th u sL y s io g q u il la sp .

e r io h th u sL y s io s q u i l la n . sp .

e ir o h th u s and p o s t la rv a e

flonodactylug g u e re n i p o s t la rv a e

O dontodacty lug hanse n i p o s t la rv a e

U n id e n ti f ie d stom atopods U n id e n tif ie d c ru s ta c e a n s

46

5 ,574

651

515

81

902

1 ,046164

290

112

114

54

148

1426159

P e rc e n t f r e ­quency o f o cc u rre n c e

A ggregatet o t a lvolume

P e rc e n tag g re g a te

t o t a lvolume

P rov ince

.6 1 0 .5 K

2 6 .4 1186 .5 2 .3 N

10.2 215.3 .4 I

1 0 .4 1 52 .4 .5 I

5 .1 62 .5 .1 V

1 5 .5 253 .6 •4 I

12 .9 446 .6 .8 N5 .5 105 .5 .25 .6 2 87 .0 .5 B

oi

Total”number oforganisms

MOLLCSCAH etaropoda

A tla n t id a eU n id e n tif ie d h e te ro n o d s

P te ropod sC av o lin id ae

C aT o lln la sp , U n id s n t i f le d p te ro p o d s

OotopodaA rgon au tIdas

A rgonauts h ian s U n id e n tif ie d a rg o n au ts

B o li ta e n id a eE le d o n e lla sp .

U n id e n tif ie d ootopods

499

10

1

3184

280

P ercen t f r e ­quency o f o ocu rren ee

A ggregatet o t a lvolume

P eroen ta g g re g a te

t o t a lvolam*

fV ovinoe

.2 1 .0 04 .6 169.2 .3 0

.1 5 .0 0

.1 1 .0 0

.3 12.5 03 .7 456 .5 .9 0

• 2 4 5 .0 .14

02 .4 176 .0 .3 B

Oltn

T o ta l J number o f [ auifloer ofI o rgan ism s | i n w hich

o ccu rredDeeapoda | (5*642) | (60S)

Ony choteu th i das

O nyohoteu th ls banks i i | 17Qhsnas t r eph i d as

S y m p leo to teu th lao u a la n ie n s is I 45 I 7

Octopodotsuthldas | 1 | 1

U n id e n tif ie d squ id I 5 ,561 f 605CHORDATA

T u n ic a ta I (240) | (69 )S a lp id a s

Pyrosoma sp . | 27 | 6D n id s n t if ie d s a lp s | 128 | 43

U n id e n tif ie d tu n ic a te * | 85 | 16V e r te b ra ta ( P is c e s ) I (5 ,3 3 3 ) | (772)

Sternoptyohidae ( H a o h e t f i s h e s )S te rn o p ty x d isp h an a

Pero<nt f r e ­quency o f o ccu rren ce

I A ggregate t o t a l volume

P S roenta g g re g a te

t o t a lvolume

P rov ince

(55 .4 (1 3 72 2 .2 ) (2 6 .2 )

.5 6 6 .0 .1 0

.6 309 .0 .6 0

.1 700 .0 1 .5 05 5 .0 12647.2 24 .2 0

(C .5 ) (3 3 0 .0 ) ( .« )

• T 7 6 .0 • 1 05 .9 137.2 .5 01 .5 86 .8 .2 0

(7 0 .4 ) (2 4 4 5 5 .7 ) (4 6 .7 )

.1 1 .0 0

Synodidae ( L i s a r d f i s h e s ) S ud idaeA le p isa u r id a e (L a n c e tf is h e s L ep to cephalus ( e e l l a r v a e ) M yctophidae (L a n te m f is h e s ) B e lo n id ae (H e ed le f i sh e a ) Hemi rharaphi dae (H a lfb e a k s )E x oco etidae ( F ly in g f i s h e s )M acruridae (G re n a d ie rs )A ulostom idae (T runpetfishes)

Aulostomus c h in e n s isS yn gn a th idae (P ip e f is h e s

and S e a h o rse s )Hippocampus kudoU n id e n ti f ie d p ip e f i s h e s

L o photidae (O a r f is h e s )Lophotes c a p e l le i

Totalnumber oforganisas

235

12

3531

231

14

P ero en t f r e ­quency o f o cc u rre n c e

A ggregatet o t a lvolume

P ero en ta g g re g a te

t o t a lvolume

P rov ince

.2 3 .0 B.1 2 0 .0 0.4 3 2 .0 0.5 7 .2 B

1 .5 7 9 .0 .2 0.2 5 2 .0 .1 B.1 3 0 .0 B

1 .9 1740 .0 3 .3 0.1 2*0 0

• 3 7 .0 I

.1 1 .0 ¥• 2 1 .5 ¥

.1 1 5 .0 0

cn«a

T o ta lnumber oforganisms

Number o f stom achs in w hich o cc u rre d

H o lo c e n tr id a e ( S q u i r r e l f i s h e s )

S phyraen id ae ( Bar raou das )Polynem idae (T h re a d f in s )P r ia o a n th id a e (B ig -e y e d )Carangid&e («Jacke)

D ecap teru s sp .N au era te s d u c to rU n id e n tif ie d ja c k s

Bramidae (P b ra fre ts )T a ra c te s sp .C ollybus drachmeU n id e n tif ie d pom frete

C oryphaenidae (D o lp h in s)L u tia n id a e (S n ap p ers)C h ae to d o n tid ae ( B u t t e r f ly -

f i s h e s )

2116

4654

28449101

148

24

1

1

15

2414

16160

211

15

15

P e rc e n t f r e ­quency o f o cc u rre n c e

A ggregatet o t a lvolume

P e rce n ta g g re g a te

t o t a lvolume

Pjrovinoe

.1 1 5 .0 V

.1 5 .0 I

.1 2 .0 N

.5 9 .0 »

2 .2 4395.0 8 .4 I.1 960 .0 1 .8 0.4 4 4 5 .0 . . 9 H

1 .5 194 .5 .4 015.8 1756.6 3 .4 0

1 .9 171 .0 .3 0.1 2 05 .0 .4 0

1 .4 4 6 .0 .1 N

1 .2 50 .5 .1 N

enCD

Totalnumber oforganisms

F om aeentridae (D em oise lles )

L ab rid ae (W rasses)Cham psodontidaeB len n iid ae (B le n n ie s )

P e t r o s e i r t e s sp .U n id e n tif ie d b le n n ie s

A oan thuridae (S urgeon- f i s h e s )

Gempylidae (Snakem ackere ls)

Gempylua serpensU n id e n ti f ie d snake m ack ere ls

Scom bridae (Tunas and m a c k e re ls )Katsuwonue pelam isttsuwonua n

( s k ip ja c k )Keothunnus m acro p te ru s •'" ' (Te l lo w in ' ) ' "-------P arathunnua s i b i (®ig

eyed tu n a )

1482

2921

1067

1

84

19

1

2

P e ro e n t f r e ­quency o f o ecu rren o e

A ggregatet o t a lvolume

P ero en ta g g re g a te

t o t a lvolume

P rov inoe

.7 8 .5 ¥• 3 5 .0 ¥• 2 6 .0 0

.9 2 9 .5 B.3 1 2 .0 B

16.8 1007.2 1 .9 ¥

.1 9 .0 0

4 .5 5 34 .0 1 .0 0

1 .5 2668 .0 5 .1 B

.1 8 2 0 .0 1 .6 B

.2 2 70 .0 .5 B

Totalnumber oforganisms

Number o f stom achs i n whioh o c c u rre d

U n id e n tif ie d tu n a sHomeidae (K u d d e rf ie h e s )B oth idae ( F l a t f i s h e s )E oheneidae (Bem oras)

Remora remo raU n id e n tif ie d rem oras

B a l i s t id a e ( T r ig g e r f i s h e s )B a l i s t e s r in g e n sU n id e n tif ie d t r i g g e r -

f i s h e sM onaoanthidae ( F i l e f i s h e s ) O s tr a o i id a e (T ru n k f is h e s )

O s tra o io n d iap han a 0 . le n t ig in o s u s U n id e n ti f ie d t r u n k f i s h e s

3411

165

45

32224

1371

215

2411

15 4

24

9116

751

84

P e rc e n t f r e ­quency o f o ccu rren ce

A ggregatet o t a lvolume

P ercen tA ggregate

t o t a lvolume

P rov ince

2 .2 1093 .5 2 .0 B.1 2 .0 0.1 1 .0 1

1 .4 123 .0 .2 0.4 3 1 .0 0

2 .2 570.5 1 .1 V

8 . 3 6 9 8 .0 1 .3 N1 .5 4 9 .0 .1 V

6 .8 349.5 .7 I.1 4 .0 I

7 ,7 223 .5 .4 I

T o ta l number o f organ ism s

lfomber o f stom achs i n w hich o cc u rre d

P ero en t f r e ­quency o f o ccu rren ce

A ggregatet o t a lvolume

P ero en ta g g re g a te

t o t a lvolume

P rov ince

T e tro d o n tid a e (P u f fe r* )S ph aero id es

lag o ce p h a lu s 14 11 1 .0 768 .0 1 .5 BU n id e n ti f ie d p u f fe r» 10 12 1 .1 133 .0 .3 I

B io d o n tid a e ( F o ro u p in s- f i s h e s ) e 6 .7 8 1 .0 .2 H

M olidae (H e ad flsh e s ) R ansan ia t r u n c a te 1 1 .1 520.0 1 .0 0

U n id e n ti f ie d f i s h and f i s h rem ains 2439 529 4 6 .2 4204.6 8 .0

62

LITERATURE CITS)

Anonymous1953, E xperim en ta l f i s h in g and in v e s t ig a t io n in so u th e rn w a te rs

by th e Shonan Maru. Prog* S p t. Formosa G ovt.-C an . F is h . S x p t. S ta . f o r 1951* F is h . S e c . , pp. 1 -50 .

1954. R epo rt o f th e so u th e rn f i s h e r i e s in v e s t ig a t io n f o r 1932. Jap an ese Bur. F i s h . , Min, Agr. and F o r . , 547 pp.

1938. S ta tu s o f th e in v e s t ig a t io n o f tu n a lo n g lin e f i s h in g grounds in th e South China Sea* Formosa F is h , Mag,,So. 279, pp. 10-19 .

1951a. R eport o f South Seas Tuna F ish e ry In v e s t ig a t io n s , 1950. Kanagatra (Jap an ) IV efeo tu re F is h . E xpt. S t a . , 45 pp.

1961b. R eport o f South Seas Tuna F ish e ry I n v e s t ig a t io n s f o r1951. Kan&gawa (Jap a n ) P re fe c tu re F is h . E xpt. S t a . , 49 pp.

Ban, T.1941. On th e se a rc h f o r so u th e rn tu n a f i s h in g g rounds.

South Sea F i s h . , v o l . 7 , No. 9 , pp . 10-21 ( t r a n s la te d from th e Japanese by W. Q. Van Caapen, U .S. F ish and W ild l i f e S e r . , Spec, S o i, R p t.t F is h . Bo. 48, p r . 1 -1 2 , 1 95 1 ).

B a te s , D. H ., J r .1950. Tuna t r o l l i n g in th e Line I s la n d s in th e l a t e sp rin g o f

1950. U .S. F ish and W ild l i f e S e r . , F is h . L e a f le t 361,51 pp.

Beebe, W.1956. Food o f th e Bermuda and West In d ia n tu n a s o f th e g en e ra

P arathunnue and Meothunnus. Z o o lo g ie s , v o l . 21, Ho. 15, pp . 195-206,

B erg , L. S.1947« C l a s s i f i c a t i o n o f f i s h e s bo th re c e n t and f o s s i l*

J . IT. Edwards, Ann A rbor, M ichigan, 517 pp.B erry , S . S .

1914, The cephalopoda o f th e H aw aiian Is lan d s* U. S. Bur* F ish * , d u l l . , v o l . 32, (1 912 ), pp. 257-362.

B igelow , R. P.1931. Stom atopoda o f th e so u th ern and e a s te rn P a c i f ic Ocean and

th e H awaiian I s la n d s . B u ll . Hus. Comp. Z o o l . , v o l. 72,Ho. 4 , pp. 105-187.

Broolc, V. S,1950. Keys to H awaiian f i s h e s . Hawaii ( T e r r , ) , D iv . F ish and Game,

Spec, B u l l . , Ho. 4 , 191 pp.B rooks, IT. K.

1886. R eport on th e Stom atopoda c o l le c te d by H.M.S. "C h allen g e r" d u rin g th e y e a rs 1873-1876. C ha llen g er R p t . , v o l . 16, Ho. 2 ,pp. 1 -116 .

B ouxin, J . and R. Legendre1936. La fau ne p e la g iq u e de 1 ’A tla n tiq u e r e o u e i l l i e dans des

estom aos de geraon au la r g e du G olfe de Gascogne, P a r t I I . C ephalopodes. Ann. I n s t , O ceanogr., P a r is , v o l . 16, Ho. 1 pp. 1 -99 .

Chapman, W. H.1946, O b se rv a tio n s on tu n a - l ik e f i s h e s in th e t r o p i c a l P a c i f i c .

C a l i f . F ish and Game, v o l . 32 , Ho. 4 , pp . 165-170.

03

64

C rom w ell, T.1961. l i id -P a e i f ic oceanography , Jan uary th ro u g h March, I9 60 .

6 . S. F ish and w i ld l i f e B a r ., Spec. S o l. R p t .i F is h . No. 54, pp. 1 -9 .

De B e au fo rt, L. F.1940. The f i s h e s o f th e In d o -A u s tra l ia n A rch ip e lag o . E. J . B r i l l ,

L e id en , v o l . B, 508 pp.De B e a u fo r t , L. F . and W. H. Chapman

1951. The f i s h e s o f th e In d o -A u a tra lia n A rch ip e lag o . S. J . B r i l l ,L e id en , v o l . 9 , 484 pp.

Edmondson, C. H.1921. Stom atopoda In th e B ernioe P. Bishop Museum. B. P. B ishop

M as., Occ. P a p ., t o I . 7 , No. 13, pp . 281-302,Ekm&n, S.

1935. T ie rg e o g rap h ie des M eeres, Akad. V e r la g s g e s e l la c h .,L e lp x ig , 542 pp.

F i to h , J . S .1950. Botes on some P a o if lo f i s h e s . C a l i f . F ish and Came,

v o l . 36, Bo. 2 , p . 65.F ow ler, 3 . W.

1928. The f i s h e s o f O ceania . B. P. B ishop B u s ., Mem., v o l. 10 , pp . 1-540 .

1931. The f i s h e s o f O ceania - supplem ent 1 . B. P. Bishop M us., Mem., v o l . 11 , Bo. 5 , pp . 313-581.

1934. The f i s h e s o f O ceania - supplem ent 2* B, P. B ishop M is .,Mem., v o l . 11, Bo. 6 , pp. 385-466.

1949. The f i s h e s o f O ceania - supplem ent 3 . B. P. B ishop H us.,Mem,, v o l . 12, Bo. 2 , pp . 37-186.

G il b e r t , C. 3.1906. The a q u a t ie re so u rce« o f th e Hawaiian Is la n d « . P e r t I I . The

deep -sea f i s h e s . U. S. f i s h C o a t., B u l l . , v o l . 2 5 , pp. 575-715. O o d sll, H. C.

1958. The h ig h seas tu n a f i s h e r y o f C a l i f o r n ia . C a l i f . Div. o f F ish and Game, F is h . B u l l . , No. 51, 41 pp.

H era ld , E. S.1949. P ip e f is h e s and se a h o rse s as food f o r tu n a . C a l i f . F ish and

Game, v o l. 35, No. 4 , p . 529.H erre , A. W.

1956. F ish e s o f th e Crane P a o if io E x p e d itio n . F ie ld Mbs. N at.H i s t . , Z ool. s e r . , v o l . 21, pp . 105-107.

H ess, A. D. and J . R. R ainw ater1959. A method f o r m easure th e food p re fe re n c e o f t r o u t .

C opeia, No. 3 , pp. 154-157.H ia t t , R. W,

1947. F ood-ohains and th e food eyo le in H aw aiian f i s h ponds.P a r t I I . B io tio i n t e r a c t i o n . Am. F is h . S o c ., T ra n s . , v o l . 74, 1944, pp . 282-280.

H ild eb ran d , S. F .1946. A d e s o r ip t iv e c a ta lo g o f th e sh o re f i s h e s o f Peru . 0 . S.

N at. ¡due., d i l l . 189, pp . 561-572.H o lth iu s , L. B,

1946. The Deeapoda U aorura o f th e S r .e l l lu s E x p e d itio n I .5 . J . B r i l l , L e iden , 178 pp.

Jo rd a n , D. S. and B. W. Evermann1905. The a q u a tic re s o u rc e s o f th e H aw aiian I s la n d s . P a rt I . The

sho re f i s h e s . U. S* F ish Coxun., B u l l . , v o l . 25 , pp. 1-574.

65

Kanamura, H. and H. Yaxaki1940a. R aport on e x p e rim en ta l f i s h in g by th e Shonan Maru in

I937i I n v e s t ig a t io n o f tu n a lo n g lin e f i s h in g grounds in th e E ast P h i l ip p in e S ea . Formosa S o r t.-G e n . F is h . K xpt.S t a . , P u b l., ho. 21 | pp* 1 -65 .

1940b. R epo rt o f th e i n v e s t ig a t io n o f f i s h in g grounds by th eShonan Maru in 1937« In v e s t ig a t io n o f tu n a lo n g lin e f i s h in g grounds in th e South China Sea. Formosa G ovt,-G en. F is h .E x p t. S t a . , P u b l. , No. 21 , pp . 6 7-117 .

K arpev ioh , A. F .1941. The r a t e o f d ig e s t io n in some f is h e s o f th e Black Sea.

Z ool. Z h u rn a l, v o l . 20, No. 2 , pp, 262-257.Kemp, S.

1513. An aocoun t o f th e C ru s tac e a Stom atopoda o f th e In d o - f t to if ie re g io n . In d ia n JAis., Rem., v o l . 4 , Mo. 1 , pp. 1-127,

K ish lno uye , K.1917. The food of tu n a a . S u isan Gakkal Ho, v o l . 2 , No. 1 , pp. 106-

108 ( t r a n s l a t a d from th e Japanese by W, 0 . Van Campen,U. S . F iah and W ild l i f e S e r . , P a c i f ic Ooeanic F ish e ry In v e s t ig a ­t i o n s , T ra n s la t io n No. 29, 3 pp. )•

1924. O b se rv a tio n s on th e s k ip ja o k f i s h in g g rounds. S u isan Gakkai Ro, v o l . 4 , No. 2 , pp. 87-92 ( t r a n s l a t e d from th e Japanese by W. 0 . Van Campen, U. S . F is h and W ild l i f e S e r . ,Spec. S c i . R p t .i F is h . No. 19, 1S50, pp. 1 2 -14 ).

L egendre, R.1954. 1a fau ne p e la g iq u e de l ’A tla n tiq u e au la rg e G olfe de

Gascogne, r e c u e i l l i e dans d es estom acs de germona. P a r t 1.Po i s s o n s . Ann. I n s t . O cean o g r., P a r i s , v o l . 14, No. 6 ,

pp. 249-418.

66

67

1940* La fauna p e la g iq u e da 1 ’A t1a n tiq u e au la rg e du G olfe daGesoogne, r e o u a l l l i a dans dee estom aos da germ ons. P a r t 111. In v a r ta b rs s (oaphalopodaa e x c l u s . ) . P a r a s i te s dugprmon.Ann. I n s t . O oeanogr., P a r le , yoI . 20 , l o . 4 , pp . 127-810.

H a r tin , A. C ., R. H. Gensoh, and C. P. brown1946. A lte rn a t iv e methods i n u p land game b ird food a n a ly e ie .

Jo u r. W ild l i fe Management, <«01. 10 , Do. 1 , pp. 8 -12.Marukawa, H.

1959. F is h e r ie s o f th e South Sea I s la n d s i N a tu ra l food o fsk ip ja c k and tu n a s . S ou th Sea F i s h . , v o l . 5 , No. 7 , pp . 12-14 .

Mi yam*, T . , K. S aruya, and T. Hasegawa1989. On th e o h a ra o te rs o f th e f a t s o b ta in e d from v a r io u s b o d ily

p a r ts o f f i s h . P a r t I I I . B u ll . Jap an ese Soo. S o i. F i s h . , v o l . 8 , No. 4 , pp. 185-186.

Moore, H. L.1951. E s tim a tio n o f age and grow th o f y e l lo w f in tu n a

(Heothunnus m a o ro o te ru a ) i n Haw aiian w a te rs by s i as f r e q u e n c ie s . U. S . F ish and W i ld l i f e S e r . , F is h . B u l l . , v o l . 52, l o . 65 , pp . 135-149.

Nakamura, H.1936. On th e food h a b i ts o f y e l lo w f in tu n a , Keothunnus m aoropterus

(S o h le g e l) from th e C elebes S ea. B at. S iB t. Soc. Form osa, T r a n s . , v o l . 26 , No. 148 , ( t r a n s l a t e d from th e Japanese by W. 0 . Van Campen, 0. S . F is h and W ild l i f e S e r . , Speo. S o i.R p t .i F is h . No. 23, 1950, pp. 1 -8 ) .

1943. Tunas and s p e a r f i s h e s . S cience o f th e S eas , v o l . 5 , No. 10 ( t r a n s l a t e d from th e Japanese by W. G. Van Campen, U, S. F ish and W ild l i f e S e r . , Spec. S o i. R p t .i F is h . No. 48 , 1951,

pp. 1 3 -4 0 ) .

68

1949* Tunas and tu n a f i s h in g . Takeuchi B ookstore« Tokyo« 118 pp.Okuraa, 7 .« K. Im aisum i, and J . llakl

1935. I n v e s t ig a t io n o f South Sea f i s h e r i e s by th e Shonan Mann I n v e s t ig a t io n s o f tun a f i s h in g g rounds. Prog. B pt. Formosa G ovt.-G en. F ish . E xp t. S ta . f o r 1933, F is h . S e o ., pp. 120-123,

B ic k e r , W. E.1946. P ro d u o tio n and u t i l i s a t i o n o f f i s h p o p u la tio n s .

S c o l. M onogr., v o l . 16, Bo. 4 , pp. 373-391.R o n q u illo , I . A.

1950. Food o f P h i l ip p in e tu n a s and d o lp h in s . Bur. o f F i s h . ,M anila (mimeographed r e p o r t ) 11 pp.

S c h a e fe r , H. B. and L. A. W alf'a 'd1950. B io m etric com parison betw een y e l lo w f in tu n a s (N eothunnus)

o f Angola and o f th e P a o if lo C oast o f C e n tra l America.U, S, F is h and W ild l i f e S e r , , F is h . B u l l , , v o l . 51, Bo. 56, pp. 425—445.

S o h u l ts , L. P.1943. F ish es o f th e Phoenix and Samoan I s la n d s o o l le o te d in 1939

d u rin g th e e x p e d it io n o f th e U .S .S . "B u sh n e ll." U. 8 . H at. i f c s . , B u l l . 180, 316 pp .

S e rv e n ty , D. L.1941. The A u s tra l ia n tu n a s . C ouncil S e i . and In d u s t . R e s .,

A u s t r a l ia , Pam phlet Ho. 104, 48 pp .S h a p iro , S .

1950. The Jap an ese lo n g lin e f i s h e r y f o r tu n a s . U. S. F ish a id W ild l i f e S e r . , Comm. F is h . R ev ., v o l . 12 , lfo. 4 , pp. 1 -2 8 .

69

S u y e h iro , Y,1942* A study on th e d ig e s t iv e system end f e e d in g h a b i ts o f fish *

«Japanese Jo u r . ¿ o o l . ( v o l. 10, Ko. 1 , pp. 1-303 .S v erd rup , H. U .( M. W. Johnson , and R. Vi. Flem ing

1946. The ocean s, t h e i r p h y s io s , c h e m is try , and g e n e ra l b io lo g y . P r a n t ic e - H a l l , New York, 1087 pp.

Takayama, I . and S. Ando1934. A s tu d y o f th e "maguro" (Thunnus) f i s h in g in 1930.

Jo u r . Japanese la p . F is h . S x p t. S t a t . , Ho. 5 , Paper No,38, pp . 1 -21 .

T e s te r , A. L.1932. Food o f th e sm all mouthed b lack b aa s , M icrop terus dolom leu.

i n some O n ta rio w a te rs , P ub l. O n ta rio F ish R es, L ab ., No. 46 , Univ. o f T oronto P ubl. B i o l . , No. 36, pp . 169-203.

T in k e r , 8 . W.1944. H aw aiian f i s h e s . Tongg, H onolu lu , 404 pp .

Tow naley, S . J .1950. A du lt and l a r v a l stom atopod c ru s ta c e a n s o c c u rr in g i n H awaiian

w a te rs , tt. S . t h e s i s , D ep t, o f 2 o o l . , Univ. o f H aw aii, 95 pp. W alfo rd , L. A.

1937. M arine game f i s h e s o f th e F a c if io C oast - A laska to th e E q u a to r . U niv. o f C a li fo rn ia P re s s , B e rk e ley , 209 pp.

W eber, M. and L. F . De B e au fo rt1911-1936. The f ia h e s o f th e In d o -A u s tra lia n A rch ip e lag o .

E, J . B r i l l , L e id en , v o ls . 2 -7 ,W elsh, J . P.

1949. A p re lim in a ry s tu d y o f food and fe e d in g h a b i ts o f Hawaiian kaw&kawa, m ahlm ahl, ono, aku , and a h i . Hawaii ( T e r r . ) , D iv. F ish and Game, Spec. B u l l . , No. 2 , 1950.