Fish Foraging on an Artificial Reefin Puget Sound, Washington
GREGORY J. HUECKEL and R. LEE STAYTON
Table 1. - Length classes of fish collected fromthe study area off Edmonds. Wash., betweenAugust 1977 and December 1978.
The Study Area
The artificial reef is located off thewest shoreline of Edmonds, Wash., 24
Medium and large fish lover 121 mmforallthree species) foraged more on organismsassociated with the artificial reef than didsmall fish of the same species. Abundance ofpreferred food items of medium and largestriped seaperch and quillback rockfishassociated with the artificial reef was animportant factor in attracting large numbersof these species. Conversely. medium andlarge pile perch were largely absent from theartificial reef due to a lack ofpreferred fooditems.
with successional development of organisms growing on the artificial reefs.
This study was designed to determinethe degree of foraging by two embiotocids (Embiotoca lateralis and Rhacochilus vacca) and one scorpaenid(Sebastes maliger) on organisms associated with an artificial reef in PugetSound to increase our knowledge of thechanges in the structure of the fish community during the reef's early stages ofsuccessional development.
Materials and Methods
'Greater than 100 tlsh, either schooling orsolitary. observed per dive.2 Less than 10 fish observed per dive.
km north of Seattle (Fig. 1). It was builtduring the summer of 1976, and is composed of 88 tire modules constructedfrom 10,000 discarded tires (Walton,1979). Five different configurations werespaced in groups on a flat sand bottom,occupying a total surface area of 1,450m2 in an 11- hectare area between 10 andIS m below mean lower low water. Theartificial reef lies 60 m offshore from ariprap breakwater and 200 m south of aferry pier. Algal and invertebrate growthon the artificial reef began during thespring of 1977 (Hueckel, 1980). Thesurface of the tires forming the artificialreef was covered by a lush growth ofalgae in which a dense population ofcrabs, shrimp, amphipods, and harpacticoid copepods took refuge.
Field and Laboratory
All fish were collected for this studyby spearfishing between August 1977and December 1978. Collected fish weredivided into three length classes (Table1). Large numbers' of striped seaperchand quillback rockfish were observed inthe study area and were speared exclusively from the artificial reef. Small pileperch also occurred around the artificialreef in large numbers, while mediumand large pile perch were scarce2
•
Schools (footnote 1) of medium and largepile perch were subsequently observednear the riprap and ferry pier pilings.Pile perch from all length classes werespeared from the artificial reef, riprap,and ferry pier pilings. All fish were
121-250 '251121-250 ~251121-200 ~201
~ 120-120
120
Length group (mm)
Small Medium Large
Striped seaperchP,le perchQuillback rockfish
Species
ABSTRACT- This study was designed todetermine the degree of foraging by stripedseaperch, Embiotoca lateralis; pile perchRhacochilus vacca; and quillback rockfish.Sebastes maliger. on organisms associatedwith an artificial reef in Puget Sound, Wash.Stomachs ofthese fish species, dissectedfrom609 fish speared on, around. and near theartificial reef between August 1977 andDecember 1978, were examined and thecontents were compared with organismspresent in the immediate area.
Gregory 1. Hueckel is with the WashingtonDepartment of Fisheries. 115 General Admmistration Bldg.• Olympia. WA 98504. R. LeeStayton is at 157 2nd St.. Framingham. MA01701.
Introduction
Fishermen and scientists have knownfor centuries that fish are attracted tosolid objects. This knowledge has beenused to increase harvests by creatingartificial reefs on sand bottoms, therebyincreasing the numbers of economicallyimportant fishes in the area.
Many factors are important to thesuccess of an artificial reef in attractingfish, including the presence of food items(Breder and Nigrelli, 1938). Fager (1972)observed that organisms growing on experimental1 m cubes off La Jolla, Calif..influenced the types of predators attracted to the cubes. Walton (1979) determined that new tire reefs in Puget Sound,Wash., attracted a higher percentage ofsurfperch (Embiotocidae) and rockfish(Scorpaenidae) than adjacent tire reefs1 year older. He speculated that changesin the fish community are correlated
38 Marine Fisheries Review
Figure I.-Study area and location in Puget Sound.
SEATTLE
EDMONDS STUDY SITE
EdmondsFerry
Terminal
,
N
l'
100m
\\
"Artificial Reef Area _~ _
Rip-rap
N
l'40km
zc...uo
speared during the mid-morning hoursexcept in winter months. Striped seaperch and quill back rockfIsh were takenat night during winter since their abundance was highest during this time. Nopile perch were collected during winterdue to their absence from the study area.
In the laboratory collected fIsh wereweighed, measured. and labeled. Stomachs were removed and preserved withIO percent buffered FormalinJ
• Due totheir extremely small size, we defInedstriped seaperch and pile perch "stomachs" as the anterior one- quarter of theirdigestive tract. Stomach contents wereemptied into Petri dishes and examinedunder a dissecting microscope (10-30X).Individual prey items were identifIed,blotted dry, weighed to the nearest0.001 g, and enumerated.
Prey items were ranked by the Indexof Relative Importance (IRI) developedby Pinkas et al. (1971). This index wascalculated as IRI = FO(N+ W), whereFO is the percentage frequency of occurrence of each prey item, N is thenumerical percentage of each prey itemcontributing to the total diet, and W isits percentage of weight. IRI values forprey items in fIsh from each length classwere totaled, and were expressed as apercentage of the total IRI.
The substrate from which the fIsh werefeeding was determined by matchingprey items in the fIsh stomachs to theirrespective habitats. Habitats of prey weredetermined from benthic cores, planktonnet tows through the algae covering thetire surfaces, and visual observations.Prey items were assigned to one of sixdifferent categories: 1) ArtifIcial reef,2) riprap and ferry pier pilings, 3) infauna(on and in sand), 4) epifauna (free moving. in reef algae and sand), 5) planktonic,and 6) unknown. Category 2 applies toonly those prey items from pile perchspeared around the riprap and ferry pierpilings.
To correlate feeding habits with preyhabitat we assumed fIsh did not migratefrom outside of the immediate area ofcapture during feeding. This assumption
Reference to trade names or commercial firmsdoes not imply endorsement by the NationalMarine Fisheries Service. NOAA.
seems justifIed since 1) striped seaperchand pile perch were observed feeding inthe same area over extended periods oftime; 2) prey found in the anterior gutsuggest recent ingestion; and 3) a lack of
extensive migratory movements by quillback rockfish was shown by Walton(1979). However, a few stomachs frommedium and large striped seaperch andpile perch from the artificial reef con-
June-July /982. 44(6-7) 39
tained trace amounts «0.1 percent IRl)of contents foreign to the reef indicatingthey migrated from other areas afterfeeding. Infrequent occurrence of theseforeign contents suggests migrations areuncommon.
Feeding Observations
Observations of striped seaperch , pileperch, and quill back rockfish feedingaround selected tire modules of the artificial reef were conducted during 845-minute periods. Twenty stations wereestablished, each station encompassingone side of a tire module (7.6 m\ andthe sand area (15.0 m2
) immediately infront of it. During each 5- minute observation period, one of the authors satapproximately 3.3 m away from the tiremodule and observed fish feeding fromthe area. Each time an individual fishtook a "bite" from the substrate, thespecies and length class of the fish, andthe type of substrate were recorded. Carewas taken not to count the same fishfeeding more than once during theperiod. Striped seaperch and pile perchgenerally foraged in small aggregations« 10 fish) so that individuals could beidentified. Once an aggregation left thestation, it usually did not return withinthe observation period. Occasionally
larger aggregations (> 10 fish) foragedfrom the stations, in which case theremay have been some repetitive counts.However, this happened so infrequentlythat if there was any repetition, we feel itdid not have any significant affect on theresults of these observations. Quillbackrockfish individuals were easily identifiedas they always remained sedentary inconcentrations of not more than 10 fishper station.
Results
We identified prey organisms from 161striped seaperch, 190 pile perch, and194 quillback rockfish from seven different phyla (Table 2\.
Striped Seaperch
We examined 27 small. 104 medium,and 49 large striped seaperch stomachs.Stomachs from 12 medium and from 7large specimens were empty (Table 3).
Harpacticoid copepods and gammaridand caprellid amphipods dominated thediet (98.5 percent IRI) of small stripedseaperch (Table 3). We classified theseprey organisms as epifauna since theywere present in algae on the artificialreef, and in sand. Small striped seaperchstomachs contained small amounts (1.0
percent lRl) of organisms which hadbeen observed only on the artificial reef,primarily barnacles, Balanus glandula.
Medium striped seaperch foraged onepifauna (43.6 percent IRI), consistingprimarily of gammarid amphipods andharpacticoid copepods; planktonic crustaceans (42.8 percent IRI), consistingentirely of brachyuran crab zoea obtained during the spring months: andbrachyuran crabs (10.6 percent IRl) andB. glandula (1.3 percent IRl), from theartificial reef (Table 3).
Large striped seaperch fed from manyhabitats. Planktonic crustaceans (brachyuran crab zoea) comprised 38.0 percentIRI; epifauna (primarily gammarid andcaprellid amphipods) accounted for34.8 percent IRI. Organisms associatedwith the artifIcial reef structures (primarily caridean shrimp and brachyurancrabs) made up 13.8 percent IRI, whileinfauna (primarily polychaete annelids)accounted for 12.1 percent IRI (Table 3).
Pile Perch
We collected 71 small, 77 medium,and 52 large pile perch; 19 small, 42medium, and 39 large pile perch werespeared from the riprap and ferry pierpilings: and 52 small, 35 medium, and13 large specimens were speared from
Table 2.- Habitats of organisms identified from stomachs of striped seaperch, pile perch, and quillback rockfish speared from the study area off Edmonds, Wash., from August1977 through December 1978.
Artificial reef
ArthropodaBalanus glandulaCaridea sp.
HippolytidaeEualus spp.Heplacarpus breviroslrisPandalus danae
Brachyura sp.Brachyrhyncha sp.
Cancer oregonens isLophopanopeus bellus
Oxyrhyncha sp.Pugetlia gracilis
EctoproctaMembranipora sp
MolluscaOdosloma sp.
ChlorophytaViva spp
PhaeophytaLaminaria saccharina
Infauna
AnnelidaPolychaeta sp.
ArthropodaOstracoda ICypridinidae)CumaceaTanaidacea
MolluscaCfinocardium nuttalliiPandora filosaTransenella lantillaPolinices lewisii
Epifauna
ArthropodaHarpacticoidaAcanthomysis sp.GammarideaCaprellideaPaguridea
VertebrataCottidae
Planktonic
ArthropodaCalanoida sp.EuphausiaceaBrachyura (zoea)
VertebrataAmmodytes hexapterusClupea harangus pallasii
Riprap/ferry pier pilings
AnnelidaSerpulidae
ArthropodaBalanus glandulaBrachyrhyncha sp.Oxyrhyncha sp.
Pugetlia gracilis
MolluscaMytilus edufisCollisella pelta
Unknown
ArthropodaCrustacea spMysidacea
MolluscaGasfropoda sp.
VertebrataTeleostei sp.
40 Marine Fisheries Review
Percent Index of Relative Importance (IRI)'
Table 3.-Stomach contents identified from striped seaperch speared from the artificial reef oNEdmonds, Wash., from August 1977 through December 1978.
Small Medium Large
In 27; Oempfy) In 104; 12 empty) (n ~ 49; 7 empty)
Taxonomic Classification
AnnelidaPolychaeta sp 09 116
Serpulidae 08 OA
ArthropodaCrustacea sp. 07
Harpactlcoida 585 4ABalanus glandula 0.8 13 OAAcanlhomysis sp. 03Tanaidacea 03 05Gammandea 353 39.0 28.1Caprellidea 4.7 02 6AHippolytidae 24
Eualus spp. 21Heptacarpus brevlfostns OA
Pandalus danae lABrachyura SP lOA 46
Brachyura (zoea) 42.8 38.0Brachyrhyncha sp 02
Cancer oregonensis 07Pugeltia gracilis 13
EctoprocfaMembran/pora sp 02
ChlorophytaUlva spp. 05
-Total 998 100.0 998
Habltaf classification
Artificial reef 10 11.9 13.8Infauna 03 0.9 12.1Eplfauna 985 436 348Planktonic 42.8 380Unknown 08 1.1
-- -Total 99.8 100.0 99.8
'Greater than 0.1 percent IRI.
June-July 1982, 44(6-7) 41
We collected 229 quill back rockfishfrom the artificial reef between AugustJ977 and December J978. Thirty weresmall. 99 were medium, and 100 werelarge. Empty stomachs were found in 2small, 19 medium, and 14 large specimens (Table 5).
Small quillback rockfIsh foraged primarily on caridean shrimp, Pandalusdanae, and brachyuran crabs from theartifIcial reef (51.8 percent IRI), as wellas planktonic euphausids and calanoidcopepods (34.1 percent lRl), and epibenthic gammarid amphipods (12.4 percent lRI) (Table 5).
Medium and large quillback rockfighobtained 95.0 percent lRl and 92.5 percent lRl of their respective diets fromthe artificial reef, foraging primarily onthe caridean shrimp. P danae, andcrabs (Table 5). Planktonic brachyurancrab zoea contributed small amountsto medium and large quillback rockfishdiets (4.6 percent and 4.7 percent,respectively), obtained exclusively during the spring months.
Feeding Observations
Feeding observations took place onfour different days in September, October, and November of 1978. During 7hours of observations, 353 striped seaperch, 197 pile perch, and 4 quillbackrockfish were observed feeding (Table6).
Striped seaperch and pile perch wereobserved to forage in a grazing mannercharacteristic of many embiotocids(Turner et aI., 1969; Bray and Ebeling,1975). Search for prey items was conducted with the head directed towardthe substrate. Rapid pectoral fIn movements stabilized the fish and feeding bitesfrom the substrate were quick and distinct. At times fIsh were observed tofeed interchangeably from tires andnearby sand. Feeding from the artifIcialreef was primarily from the algae covering the tire surfaces. Through examination of their stomach contents, fish wereshown to be picking small invertebratesfrom algae shelters. On numerous occasions, striped seaperch were seen pickinglarge pieces of algae from the substrate,followed by rapid mouth and opercular
Quillback Rockbshthe sand (68.1 percent lRI), and barnacles, B. glandula: mussels. Mytilusedulis: and limpets, Collisella pelta, fromthe rocks and pilings (31.1 percent lRI)(Table 4). Medium pile perch capturedfrom the artificial reef foraged basicallyon clams, T tantilla, and ostracods fromthe sand (92.7 percent lRl) with onlytrace amounts (1.4 percent lRl) of theirdiet originating from the artificial reef(Table 4).
The diet of large pile perch spearedfrom the riprap and ferry pier pilingshabitats consisted primarily of barnacles,B. f!,landula, and mussels, M. edulis (95.0percent lRI) (Table 4). Around the artificial reef, large pile perch fed less onencrusting organisms (60.4 percent lRl)and more on sand-oriented organisms(34.4 percent lRI) than they did aroundthe riprap and ferry pier pilings.
the artificial reef. Empty stomachs occurred in one small, four medium. andfive large pile perch (Table 4).
Small pile perch collected from theriprap, ferry pier pilings, and the artificialreef used the sand habitat for their primary source of food. Benthic crustaceans(ostracods and the clam Tf'ansenellatantilla) made up 93.3 percent lRl of thediet of small pile perch collected fromthe riprap and ferry pier piling habitats,and 87.3 percent lRl of the diet fromsmall pile perch collected from the artificial reef (Table 4). Only 7.9 percent lRlof the diet of small pile perch collectedfrom the artilicial reef was obtained fromthe reef. and that consisted of the gastropod Odostoma sp.
Medium pile perch speared from theriprap and ferry pier pilings consumedclams. T tantilla. and ostracods from
movements resulting in ejection of thealgae into the open water. This processwas repeated several times by the samefish with the same piece of algae; thiswas probably a method of obtainingsmall invertebrates from the algae. Itwas not uncommon to find incidentalpieces of algae in stomach samples ofperch.
Medium and large striped seaperchfed more from the artificial reef than didsmall striped seaperch (Table 6). Themajority of pile perch from all lengthgroups were observed feeding from thesand (Table 6). Overall, the numbers ofstriped seaperch and pile perch observedfeeding during the observational periodsdecreased with increasing size of thefish.
The small number of quillback rockfish observed feeding may be attributableto their preference for relatively largeprey items. Feeding by quillback rockfishis probably confined to short intervalsduring the course of a day or night. Oneljuillback rockfish was seen consuminga shiner perch. Cvmarogasteraggregata.immediately above the artificial reef.while the remainder were seen eatingthe caridean shrimp. P danae. on theartificial reef.
Discussion
Striped seaperch from all lengthgroups foraged primarily on small, noncalcareous epibenthic crustaceans. Mostprey items were present on the artificialreef and sand, making it impossible to
determine the specific habitat fromwhich these fish were feeding. Observations of striped seaperch revealed thatmedium and large fish fed predominatelyfrom the artificial reef, and that smallstriped seaperch fed equally from bothhabitats.
The optimal foraging theory states "...an optimal consumer should be willingto expend more energy Ior time I to findand capture food items that return themost energy per unit of expenditure uponthem" (Pianka, 1974). Assuming stripedseaperch feed optimally, the net energygained per unit of feeding time expendedby medium and large striped seaperch isgreater by feeding over the reef than byfeeding over sand. This may be due, inpart, to the larger size, or density, of
Table 4.-Slomach conlen!s idenlified from pile perch speared from Ihe arlificial reel, riprap, and ferry pier pilings oft Edmonds, Wash., from August 1977 IhroughDecember 1978.
Percent Index of Relative Imparlance (lRI)
Small Medium Large
282 549- -999 998
NIA 7.92.3 NIA
933 8734.3 4.6
99.9 998
04
0.302
0.30.3
0.3197
703 32-99.7 999
14 NIANIA 95.692.7 4353
03
997 99.9
ArthropodaOstracoda (CypridinidaelBalanus glandulaMysidacea
Acanthomysis sp.CumaceaGammarideaHippolytldaePanda/us danaePaguridaeBrachyura
Brachyura (zoea)Brachyrhyncha
Cancer oregonenSISOxyrhyncha
Pugettia graci/is
MolluscaGastropoda
Collisella peltaLirularia IirulatusOdos/oma sp.Polinices lewisii
Clinocardium nuttall,Mytilus edulisPandora IilosaPectinidaeTransenella tantilla
Total
Habitat classification
Artificial reefRipraplferry pier pilingsInfaunaEpifaunaPlanklonicUnknown
Total
'Grealer Ihan 0.1 percent IRI.
Ripraplferry pier pilings(n 19:0emply)
65.1
4.3
23
ArtifiCialreef
(n 52: 1emply)
324
46
79
R,praplferry pier pilings(n 42: 2 emply)
26911 7
0310
03
04
0483
94
41 2
999
NIA31 1681
0.3
04
999
Arlificialreef
(n 35: 2 empty)
22102
0206
51
Rlpraplferry pier pllmgs(n 39: 2 emply)
02753
09
ArtifiCialreef
(n 13; 3 empty)
34564
2.0
0.2
2830
1.2
050.2
020.7
294
1000
604NIA344
5.2
100.0
42 Marine Fisheries Review
invertebrates that take refuge in the algaegrowing on the artifJcial reef in comparison with those found on open sand.Assuming small striped seaperch alsofeed in an optimal manner. there was nodifference in the energy gained from theartificial reef or from the sand.
Throughout this study. striped seaperch were present in large numbersaround the artifJcial reef. Walton (1979)observed that striped seaperch wereabsent from the study area prior to theplacement of the artifJcial reef, eventhough Hueckel (1980) discovered thatpotential prey items were abundant onand in the sand. Walton (1979) also notedembiotocids were the fJrst group of fJshto colonize the artifJcial reef, even beforealgae and invertebrates started growingon the tire surfaces, and that the averagesize of early colonizing striped seaperchwas smaller than striped seaperch on theolder riprap and nearby sunken boathulls, both of which were covered withinvertebrates and algae. Observationsmade by the author on a bare, newlyconstructed concrete reef in Puget Soundshow an overwhelming majority of 8,200small to only 76 medium and large stripedseaperch. Small striped seaperch appearto be attracted to artificial reefs forshelter or orientation; larger perch aresubsequently attracted by the presenceof organisms growing on the surface ofthe reefs.
Stomach contents from small pileperch captured from all habitats, as wellas the in situ feeding observations, indicated a diet composed primarily oforganisms living in or on sand. TheartifJcial reef, riprap, and ferry pierpilings provided very small amounts ofprey organisms for small pile perch, yetthey were observed near all these structures in large numbers. Like small stripedseaperch ,small pile perch also colonizedthe artificial reef prior to the development of organisms on the surface of thetires (Walton, 1979), and were apparentlyattracted by the cover (or orientationpoints) offered by the artifJcial reef.
Few medium and large pile perch wereobserved around the artifJcial reef incontrast to many seen around the riprapand ferry pier pilings. Medium and largepile perch fed primarily on barnacles andmussels around the riprap and ferry pier
June-July 1982. 44(6-7)
Table 5.-Stomach conlents identified from quillback rockfish speared from the artificial reef offEdmonds. Wash.. from August 1977 through December 1978.
Percent Index of Relafive Importance (IRI)'
Small Medium Large
(n - 30; 2 empfy) (n gg; 1g empty) (n ~ 100: 14 empty)
Taxonomic Classification
AnnelidaPolychaeta sp.
ArfhropodaCrusfacea sp. 0.3
Calanoida 238Gammaridea 12A 0.3 0.7Euphauslacea t03Caridea sp 85 40 lA
Eua/us spp 2.6Panda/us danae 300 715 420
Brachyura sp. 12.2 15.3 46.7Brachyura (zoeal 4A 3.3
Brachyrhyncha sp. 0.5 1.0 03Cancer oregonensis 0.6 1 7Lophopanopeus bel/us 0.2Pugetfia gracilis 02
VertebrataTeleostei sp 0.5 lAAmmodytes hexapterus 02C/upea harengus pal/as, 1.4Coftldae sp. OA
PhaeophytaLammar;a saccharina 06
-997Total 993 99.9
Habitat classification
ArtifiCial reef 51.8 950 925Infauna 0.2Epifauna 12A 03 1.1Planktonic 34.1 4.6 4.7Unknown 0.8 lA
- -Total 99.3 999 997
'Greafer fhan 0.1 percenf IRI.
Table S.-Numbers of striped seaperch, pile perch, and quilfback rockfish feeding on the sand and arfificial reefoff Edmonds, Wash., during 7 h of observations.
Striped seaperch Pile perch Quilfback rockfish
Small Medium Large Small Medium Large Large
AR'S' --- --- ---Station AR S AR S AR S AR S AR S AR S
1 10 8 5 4 3 3 3 3 1 0 0 0 0 02 6 7 1 0 1 0 1 2 0 0 0 0 0 03 12 43 2 0 2 0 1 17 0 0 0 0 0 04 14 7 7 6 2 1 5 0 4 5 2 2 0 05 6 5 3 0 3 0 0 0 1 4 0 0 0 06 2 3 2 0 3 0 1 3 0 0 0 0 0 07 7 4 3 0 3 2 3 4 3 0 0 0 0 08 4 0 4 5 0 0 3 4 0 3 0 3 0 09 6 0 3 0 2 0 1 1 0 1 0 0 2 0
10 2 0 8 0 0 0 1 9 0 0 0 0 0 011 3 11 0 0 1 2 2 4 0 0 0 0 0 012 12 8 5 3 1 0 3 13 2 3 0 0 0 013 6 1 1 0 2 0 1 1 0 0 0 0 0 014 1 1 4 0 0 0 0 9 0 0 0 0 0 015 0 5 3 2 0 1 1 13 1 0 0 0 0 016 3 5 1 3 0 2 1 7 0 2 1 0 1 017 9 2 0 0 0 0 1 1 1 0 1 0 1 018 2 3 2 0 2 0 0 3 0 5 0 0 0 019 2 2 1 1 3 0 1 2 0 7 0 0 0 020 3 8 1 0 0 1 4 13 0 1 0 2 0 0- - - - - - - - --Total 110 123 56 24 28 12 33 109 13 31 4 7 4 0
Percent 47.2 528 70.0 300 70.0 30.0 232 76.8 29.5 705 36A 63.6 100.0 00
'Artificial Reef.'Sand.
43
pilings; around the artificial reef feedingwas proportionally more from sand.Barnacles and mussels heavily encrustedboth riprap and ferry pier pilings. Initialbarnacle population on the artificial reefwas rapidly depleted to low numbers bystarfish predation and mussels nevercolonized the tire surfaces. Subsequentalgal growth on the tires inhibited barnacle repopulation. The small populationof barnacles and failure of mussels toattach to the tire surfaces appear tohave created a food shortage for mediumand large pile perch on the artificial reef,suggesting these food organisms are animportant attractant for these fish.
Quillback rockfish foraged more onartificial reef associated food organismsas their size increased. Medium and largequill back rockfish obtained nearly 100percent ORO of their diet directly fromthe artificial reef. Walton (1979) observedthat the average size of quillback rockfishincreased over time on the artificial reef.Small quill back rockfish inhabited theartificial reef prior to algae and invertebrate colonization, indicating smallerquillback rockfish were initially attractedto the artificial reef for reasons otherthan food. The proximity of small quill-
44
back rockfish to small crevices in theartificial reef and their quickness to dartinto these crevices when approachedsuggest they are benefiting from protection offered by the artificial reef. Subsequently. larger quillback rockfish wereattracted to the artificial reef followingthe colonization by shrimp (Hueckel,1980).
Summary
It was shown in this study the importance of organisms growing on an artificial reef to the diets of three PugetSound fish species. Medium and largestriped seaperch, pile perch. and quillback rockfish were attracted to the artificial reef more by the presence of fooditems than were the small fish of thesame species. The small striped seaperch,pile perch, and quillback rockfish usedthe adjacent sand areas and plankton toforage for much of their diet, whichemphasizes the importance of thosehabitats to these small flsh. The numerous hiding spaces in the artificial reefwere often used by the small stripedseaperch, pile perch. and quill backrockfish as a refuge and must aid inprotection from predation. The abun-
dance of preferred food items on theartificial reef for medium and largestriped seaperch and quillback rockfishwas an important factor in attractinglarge numbers of these fish species.Conversely, medium and large pile perchwere largely absent from the artificialreef due to a lack of preferred food items.
Literature Cited
Bray. R. N.. and A. W. Ebeling. 1975. Food,activity. and habitat of three "picker- type"microcarnivorous Iishes in the kelp forests offSanta Barbara, California. Fish. Bull., U.S.73:815-829.
Breder. C. M.. Jr.. and R. F. Nigrelli. 1938. Thesignilicance of differential locomotor activityas an index to the mass physiology of Iishes.Zoologica (N.Y.) 23:1-29
Fager. E. W. 1972. Pattern in the developmentof a marine community. Limnol. Oceanogr.16:241-253.
Hueckel, G. J. 1980. Foraging on an artiticialreef by three Puget Sound tish species. Wash.Dep. Fish. Tech. Rep. 53, 110 p.
Pianka, E. R. 1974. Evolutionary ecology. Harper & Row, N.Y., 356 p.
Pinkas, L.. M. S. Oliphant, and I. L. K.lverson.1971. Food habits of albacore, bluelin tuna,and bonito in California waters. Calif. Dep.Fish Game. Fish Bull. 152,105 p.
Turner. C. H.. E. E. Ebert, and R. R. Given.1969. Man-made reef ecology. Calif. FishGame, Fish Bull. 146,221 p.
Walton, J. M. 1979. Puget Sound artiticial reefstudy. Wash. Dep. Fish. Tech. Rep. 50, 130 p.
Marine Fisheries Review