Is the Spear of Istiophorid Fishes Used in Feed ing?'

ROBERT L. WISNER2

THE SPORT OF ANGLING for spearfishes-theseveral marlins and sailfishes of the familyIst~ophoridae-has fostered many books andarticles on :he behavior of these large fishes.The swordfish, Xiphius gladiusLinnaeus com­prising the family Xiphiidae, also com:nandsa very considerable following among salt­water anglers and is the subject of an ex­tensive literature. Certain beliefs have arisenconcerning the behavior and habits of thefishes comprising these game fish familiesparticularly as to their methods of obtainingfood. It seems worthwhile to attempt now anevaluation of the accumulated evidence. Onlythe true spearfishes, particularly the marlinswill be considered in detail. The broadbiliswordfish will be mentioned only occasion­ally, and the conclusions reached do not nec ­essarily pertain to this fish.

Angling lore is replete with reports of suchfishes stunning prey and trolled fish baits witha blow of the spear before devouring them.The time-honored belief that the spearfishesposse~s .their spears for the express purposeof striking or stabbing prey, however, maynow be questioned. Recently accumulatedevidence indicates that such fish can existquite readily without a spear to aid in obtain­ing food . Other evidence has cast some doubtas to whether the spear is at all commonlyemployed in such a manner.

1 Contributions from the Scripps Institution ofOceanography, New Series, No. 958. Manuscript re­ceived Mar ch 27, 1956.

2 S~ripp~ Institution of O ceanography, Universityof Californi a, La Jolla, California.

60

RECORDED OBSERVATIONS OF FISHWITHOUT SPEARS

Moore (1950) reported on a spearless blackmarlin, Makaira mazara ( Jordan and Sny­der), that was landed at a commercial fishmarket in Honolulu, Hawaii, without indi­cating the length of stub remaining. The na­t~re of the wound indicated some time lapsesince the loss. The specimen weighed 545 lbs.and was judged equal in physical conditionto normal fish of the same species.

Mr. Vernon E. Brock,Director, Divisionof Fish and Game, Hawaii, in correspondencereports " . . . a spear removed from a marlinwhich has been broken with the remainingpart that is spiraled like a corkscrew. The fish~rom which the spear was taken was, accord­mg to the fishermen, normal in all respects."

Morrow (1951) reported that a In-lb.striped marlin, M akaira mitsukurii ( J ordanand Snyder), taken with sporting tackle andtrolled bait at Otehei Bay, New Zealand, hadthe spear broken off on a long slant reachingfrom several inches behind the mandible tipto within a few inches of the eye. The breakhad completely healed and was well coveredwith skin. The injury had affected the fishfurther in that the mouth was prevented fromclosing completely, one side remaining partlyopen. However, the fish appeared to have hadno diffi~ulty in taking the bait and gave abattle said to have been entirely normal for afish of its weight.

Farrington (1942: 110) reported numbersof marlin with spears broken off. This obser­vation was made at Guaymas, Sonora, Mex-

Istiophorid Fishes- WISNER

ico . Gre y (1926: 105) mentioned a marlin inNew Zealand waters that had a brok en spear.The region of th e break is not indicated, noris the amo unt missing. Grey states, " De­prived of his weapon of defens e and for pro­curing food, th is marlin might well have beenexpected to be thin , flat , in po or condition. .N evertheless, he was solid , fat, in splendidshape. He had been compelled to rely on hisspeed. "

In September, 1952, the author examinedtwo spearless striped marlin at the MarlinClub do ck at San Diego, California. Each wascaptured with sporting tackle and trolled bait .Each spear had been broken off at about thetip of the lower jaw, as in Figure 1. Since bothstubs had healed completely and were wellcovered wit h skin , a considerable time musthave elapsed since the injuries. The fishweighed, respectively, 149Yz and 186 lbs.(official club weight). These fish were of atleast average weight for their length (Fig . 3) .M orphom etric data obtained on both speci­mens when compared with those of normalfish of the same body length and weightdisclosed no signi ficant differences in bodyproportion s.

The stomach contents of the smaller fishcomprised th e remains of 8 Pacific sauries,Cololabis saira (Brevoort), totalling 349 cc.Th e larger fish contained 5 small yellowfincroakers, Umbrina roncador J ordan and Gil­bert , totalling 785 cc., a small halfmoon,Medialuna californiensis (Steindachner), 105cc., and 1 trunk section of a Pacific saury,23 cc. The first fish had eaten a main item inth e diet of local marlin , as determined byHubbs and Wisner (1953) , but its stomachcontents were of less th an average volume.The second had eaten more than an averageamo unt , bu t chiefly of a shore species nototherwise enco untered in the food studies.

A third spea rless striped marlin was landedat the San D iego Club on September 17, 1955.This fish was not examined by the aut ho r, butwas reported to have been normal in all re-

61

FI G. 1. Spearless striped marlin , weighing 149\1,pounds. Ph ot ographed at the San Die go M arlin Club,Sept. 13, 1952, by R. Van N ostrand .

spects and fou ght strongly. The stub wasreported to be smoot hly healed and cove redwith skin. A fourth spearless fish, landed inSeptember, 1956, also was reported to bequite normal despite its loss of spear. Thisfish also was not examined by the author.

Gudger (1940) cited many examples ofpo rtions of spears hav ing been broken off ata considerable period of time before capture .All these fish had apparently surv ived thewound and had flourished since. Unfortu­nately, most reports did not estimate theamo unt of spe ar missing. One account ap-

62

proaches the incredible. During the MichaelLerner Australian-New Zealand Expedition,Miles Conrad reported seeing a marlin withthe spear sawed off, and yet the fish hadsurvived . The spear had been removed by asquare cut about midway between the tip ofthe lower jaw and the anterior edge of theeyes-the point generally selected for sawingoff a spear trophy. The fish had evidentlybeen caught by an angler, and, when the spearhad been removed, had escaped to the ocean.The growth of skin that had formed over thestub still retained the rosy glow of healthyhealing. The fish was reported to be thinnerthan a normal fish of its size. Without doubta fish so injured as to leave the upper half ofits mouth permanently open with but half anupper jaw would be seriously handicapped infeeding . The previously cited injuries had atleast left the fish with mouths somewhatsuited for grasping and holding prey. .

As stated by Morrow (op.cit.), "It is obviousthe spear is not absolutely essential to thewell being of the spearfishes." The four speci­mens under the immediate cognizance of theauthor, as well as those reported by Moore,Morrow, Brock, and Gudger, had apparentlyexisted in normal fashion despite the loss ofthe spear. None of those taken on sportingtackle had given any marked indication ofweakness, or other abnormal behavior at­tributable to loss of the spear, while strikingthe trolled bait or during the ensuing battle.

RECORDED FEEDING AND BAIT-SEIZING

HABITS

The fact that marlins can exist reasonablywell without their spears reopens the questionof how spearfish feed. Many anglers andauthors of books on angling for the largegame fishes have given accounts ofspearfishesstunning their prey and trolled fish baits witha slashing blow, before turning to devourthem. The angling methods for these fishhave long involved a slack line arrangementto allow the bait to lie " dead" in the waterfollowing the initial rush or strike of the fish.

PACIFIC SCIENCE, Vol. XII, January, 1958

Isriophorid Fishes- WISNER 63

250 .-, ---.----,--- -r- - .,---- - ,.-- --,,------,-- - .,---- - ,.-- ----,r-- ---,-- - -r- - ..,.--

oo

oo 0

o

o0 0

o 0.~...'0 0

o 0 0

o 0

• • •• •• ® .o 0 ,

• • •••a. . • i. .

200--------------_,.._------_,.._----~-_,.._--=---------

l/loZ=>1r150 - - - - - - - - - _,.._---,-,:-r.r- .....r.-.,.---,,-- -L.c-- - - - - - - ----- ------~

I­:I:

1;3100-- -"--"- - - - - - ------- - - - - - -.--- - - - - - - - - - ----:;::

50 --------- - - - - - - - - - - - - - - - ----- - - --- ---

2200! ! , !

2300 24 00 2500 26 00

TIP OF SPEAR TO FORK OF CAUDAL FIN in mm.

2700 2800

FIG. 3. Relation between weight and length from tip of spear to fork of caudal fin for striped marlin caughtnear San Diego in 1952. The two circled entries are for the two spearless fish caught that year. Their lengths arecomputed by adding the average length of spear from tip of mand ible for other marlin of the same length behindtip of mand ible. The two spearless fish are at least average weight.

According to Van Campen Heilner (1943:108-109) almost no spearfish were taken inFlorida waters before the discovery of thismeth od by the famous Captain Bill Hatch ofMiami, Florida, while experimenting withmethods of taking sailfish. Heilner statedthat Hatch, the father of the "Drop-back, "came to the conclusion that , "When the sail­fish first rushed the bait he struck it a blowwith his spear to stun it and if it didn'tcollapse then and there , something wasphoney. By immediately allowing a lot of lineto run off the reel the sailfish was fooled intobelieving he had paralyzed his preyand wouldreturn to seize it." Prior to the use of thismethod the sailfish only mauled the fish beingused as bait for kingfish and mackerel butcould not be hooked, which may indicatethat the sailfish were grasping the bait be­tween their jaws rather than striking it withtheir spears and tha t the bait was pulled fromtheir jaws or rejected before it could beswallowed.

It is known, of course , that marlin in par­ticular do not always strike a blow before

FIG. 2. Striped marlin with a deformed spear. Photo ­graphed at M azatlan, Sinaloa, Mexico, Mar . 26, 1954,by R. L. Wisner.

taking the bait. A fast rush and grab is mostfrequent. A hun gry fish, of course, is muchless apt to toy with a bait or prey than tomake haste in consuming it. Thomas andThomas (1930: 130) cited a fish that did notattempt to stun the bait with the spear. "Themarlin changed direction in his rush and, justbefore he reached the lure he swerved to oneside, as such fish nearly always do, and seizinghis prey between his jaws, whirled , splasheda trifle , and , like a ray of light as he showedhis ' gleaming underbody, turned downwardand was away." In another connection (p.122) these authors stated : "When marlin hita troll they do not grab it in their mouths asdo other fish; rather they seize it between theirupper and lower bills before swallowing, andseem to approach the lure sideways, turningit before gulping it down ." Bandini (1933)lent support to this opinion by stating, "Amarlin seizes the bait crossways in his mouthand swims away with it ."

In contrast to the foregoin g testimony,Thomas and Thomas described the feedinghabits of marlin as follows (p. 121) : "Theyfeed chiefly on anchovies, sauri [sic], sardines ,flying fish, and other small fry, charging intoschools of these unfortunates and slashing

64

right and left with their bills, before turningback and leisurely picking up those they havekilled or crippled. " Another report by theseauthors (p. 136) was that: "Marlin were every­where, scattering bait and cutting the water 'with their fins and tails ... . Terrified patchesof bait skittered across the water endeavoringto elude their pursuers who slashed relent­lessly."

Voss (1956) has contributed the followinginformation. "How well the sailfish uses thisweapon I discovered one calm winter day offStuart, Florida, when we backed our boat intoa school feeding on minnows . The sailfishcircled slowly, sails half raised, herding theirprey tighter and tighter. First one and thenanother broke from the circle and swamthrough the milling prey, thrashing right andleft with their bills. Then the predators wouldsubmerge and lazily eat the dead and stunnedminnows as they drifted down."

It is, of course, possible that a differenceexists in the method of capturing trolled baitsand free-swimming prey, even .though thespearfishes may be facile in each method.One .must give complete credence to suchobservations as made by Voss. It is evidentthat on occasion, abnormal though it maybe, the spear is used to obtain food by thrash­ing. However, the mass of observations in­dicate this to be a rather infrequently em­ployed method. The following observationsfrom the field and from studies of stomachcontents shed considerable light on the matter.

In examining the stomach contents ofmanymarlin, the author has at times noted that theheads and pectoral regions of some of the lessdigested specimens had been severely dam­aged on both sides, presumably as a result ofhaving been crushed between jaws. Alongthe same line Thomas and Thomas (op . cit.,p. 124) stated that "the bills [upper and lowerjaws]ofa marlin leave two distinct depressionson a small fish just behind the gills." Theseobservations indicate that, at least at times,the struggling prey is seized so as to kill it,or to hold it firmly preparatory to swallowing

PACIFIC SCIENCE, Vol. XII, January, 1958

it . The observations also indicate that in suchsituations the spear is not used to obtain food.If the prey had been killed or stunned or soinjured as to prevent escape the marlin wouldnot have needed to crush the prey beforeswallowing it .

That marlin can feed without the use of thespear is demonstrated by the following state­ment by Miss Francesca LaMonte of the In­ternational Game Fish Association (quotedby Hubbs and Wisner, 1953): "Dr. D. G.Maitland of Sydney, Australia, has recentlywritten us as follows: 'It may interest you toknow that I have actually watched a pair ofBlack Marlin feeding upon Physalia, like hugeRainbow Trout taking flies, and absolutelyignoring a most tempting looking mackerelbait drifting in front of their noses.' "

That prey much larger than the small coe­lenterate of the genus Physalia may be cap­tured without obvious use of the spear isindicated by another observation. During pre­liminary studies of the food of striped marlinin the San Diego area in 1952, a young blueshark, Prionace glauca (Linnaeus), a littlelonger than 24 inches, was found in thestomach of a 205-pound marlin. This shark,which had been recently ingested bore nomarks of a blow or thrust of the spear. Aroughening of its skin over rather broad areascould have been produced by the sandpaperyjaws of the marlin as it grasped and held thestruggling shark . A blow, or blows, of suffi­cient force to kill or stun the notoriouslyhard-to-subdue shark would almost certainlyhave left identifiable marks on the body .

Still another indication of feeding that cer­tainly would not call for use of the spear wasencountered by the author while examiningstriped marlin stomach contents at Mazatlan,Sinaloa, Mexico, in March, 1954. Both marlinand sailfish were feeding on a species ofargonaut. Such a relatively slow-moving mol­lusk would be as easily captured as Physaliaand would require not even the lightest tapfrom a spear.

Istiophorid Fishes - WISN ER

Until very recently non e of the studies ofthe food habits of marlin has disclosed anyingested fish that show the marks of havingbeen slashed by or impaled on th e spear.Hubbs and Wisner (1953), for example, foundno evidence of fish having been damaged bythe spear. A more definitive study of stomachcontents for the 1952 and 1954 seasons inSan Di ego has substan tia ted these findings.M iss Francesca LaM onte (correspondence)states: "In no case have I ever seen anythingthat seemed to have been slashed by the spearor impaled upon it ."

RECORDED USES OF THE SPEAR

The fact that the spear has been retainedsince possibly Upper Cretaceous, and cer­tainly since Eocene times (Berg , 1940), in­dicates th at it is much more of an aid than ahindrance to the fish. Th at the spear may, onoccasion , be used to obtain food by stabbing,or as a weapo n, is illustra ted by the followingobservations. Anonymous writers (1955a, b)recorded that during a cruise into tropicalwater s south of H awaii, "An interesting in­cident was the landing of a huge white marlin[Istiompax mar/ina (Jordan and Snyder)], es­timated to have weighed around 1,500 pounds ,which had in its stomach a freshly killedyellowfin tu na 5 feet in lengt h and weighing157 pou nds. . .. The tuna had been spearedclean through its bod y twice before beingswallowed.' ,

Another such observation from H awaiianwaters, again provided by Mr. Vernon E.Brock (correspondence), is as follows, " .. .the use of the spear to stab another fish doesoccasionally occur. One such observation bythe skipper of the territorial research vesselwas made off the K ona coast of H awaii anumber of years ago when a marlin was ob­served at the surface of th e sea with its spearth rust through the bod y of a dolp hin [Cory­phaena hippurus]. The dolphin was stru gglingvigorously and the marlin would rear out ofthe water in an appa rent attempt to preventthe flopping fish from work ing free of thespear. "

65

Zane Grey (1926: 48) repo rted finding asnapp er with a round hole in it in the stomachof a marlin caught in New Zealand waters . InTahitian waters Grey (1931: 229) quotedCaptain Mitchell, his fishing companion, asrep o rtin g his bonito bait rammed clearth rou gh by a marlin . Farrington (1937: 221)reported big dolphin " batted" into the air bymarlin and th at numbers of dolphin havebeen caught that had holes in them wheremarlin spears had pierced them.

Thi s autho r has very recentl y studied afrigate mackerel, Auxis sp ., and a sierra mac­kerel, Scomberomorus sierra Jordan and Starks,removed from marlin landed at M azatlan,Sinaloa, Mexico in March, 1954. These fish,respectively 300 and 430 mm . lon g, each borethe marks of a spear thrust th rou gh the mid­section, respectively above and below thelate ral lines . Each fish was removed by theauthor from undamaged, freshly caughtstriped marl in and wrapp ed and stor ed untilstudied. Unquestion ably, the marks weremade 'by spears as the holes were large andhad been torn out through the dorsomedianflesh of the A uxis, and through the ventro­median flesh in the Scomberomorus. Severalother fish of the same species gro ups andsimilar in bod y sizes bore no marks of thespear.

Gudger (op. cit., pp, 271-274) cited severalreports from repu table observers which in ­dicate that battles occur between swordfishand spearfish, and between members of thesetwo families and sharks . Broken spears havebeen found imbedded in the flesh of each,some obviously having been there for sometime. Voss (op . cit .) reported catching a sail­fish that had the broken bill of anoth er sail­fish pro jecting [th rough the body] on eitherside .

SPECULATI ON ON THE USES O F THE SPEAR

It seems pro bable that the spear is usedboth as an aid in food- getting and as a weap ­on. It is a rather moot question whether thecited stabbings and " battings" of larger fish

66

resulted from pugnacity, playfulness, or adesire to obtain food . The 157-pound tunacould conceivably have been regarded as anenemy by even a 1,500-pound marlin. Thebig dolphin would not seem to fit the enemycategory although the relative sizes of preyand predator were not given . If it may beassumed that marlin customarily charge theirprey to engulf it, it is then possible that thestabbings were accidental. If a spearfish is ableto overtake its prey with sufficient speed toimpale it, such speed should be more thanadequate to permit the prey to be seized.Accidental stabbings of the smaller prey seemquite plausible if one considers the almostphenomenal accuracy required of the predatorto hit and penetrate even an unsuspectingprey. In line with this view, impaling anevasive prey appears to be governed bychance. The few observations of stabbingmake it seem possible that the spear may beused against the larger fishes-those not read­ily captured by overtaking and seizing be­tween jaws.

The preponderance of evidence indicatesthe spear is not commonly used as a meansof getting food . The food content studies todate have all dealt primarily with smaller for­age animals . Presumably few others have beenfound. One must conclude that these com­prise the bulk of the food of the spearfishes.As stated earlier, few indications of stabbingand none of injury by blows have been found.The prey had evidently been overtaken andengulfed by the predators. Those spearfishfound with the spears missing had almostcertainly employed this method of gettingfood.

Examination of the spear and jaws indicatesthat the smaller forage fish and squid, theprime components of spearfish food, couldnot readily be stabbed. The spear is relativelydull at the tip and is covered by minute,sharp, backward-pointing nodules for its en­tire length. These 'nodules continue to eachjaw, where they become a raspy band of teeth .The roughness of the spear covering is at-

PACIFIC SCIENCE, Vol. XII, January, 1958

tested by fishermen who almost invariablywear gloves to avoid having their handsabraded while the fish are being boated. Itwould be difficult indeed for the dull tip topenetrate small fish. Certainly the soft, flex­ible body of a squid would be extremely diffi­cult to be impaled or to be dealt a damagingblow with so blunt a weapon . The swordfishhas a smooth, laterally flattened sword ofproportionately greater length than that of thespearfishes, but it is equally blunt at the tip.It is better suited as a flail but no better suitedfor spearing small prey. A striped marlinpoorly suited for stabbing prey was observedby the author at Mazatlan, Mexico, 1954(Fig. 2). The curve of its spear was such thata thrust would tend to slide off a relativelysmall fish.

Further evidence that the spearfishes do notcommonly slash with their spears is found intheir skeletal make-up. The construction isnot suited to free and extensive sidewise mo­tion. The istiophorids have heavy, flat, plate­like neural and hemal spines rather than the .common rodlike spines of other fishes. Theneural processes are modified into broadplatelike structures that extend far forward,almost reaching the middle of the precedingvertebra. The platelike hemal spines arefirmly attached to the hemal processes of theneighboring vertebrae, as are the neural spinesand processes . Such construction produces anexceptionally strong and inflexible, interlock­ing, bracing system. The vertebral column ofthe broadbill is less interlocked but is sofashioned as to resist greater shock fromhead-on encounters than is that of the spear­fishes.

Nakamura (1938), who studied the skele­tons of many spearfishes, concluded that"The vertebrae are most unsuited for precisemovements, and sudden changes of directionare probably impossible." Furthermore, thedeep and flat lateral surface of the anteriorpart of the body would require tremendousenergy and leverage against the resistance ofthe water to accomplish a slashing movement

lstiophorid Fishes- WISNER

sufficiently rapid to mike a small fish fleeingfor its life. Such great expenditure of energywould detract from the forward speed of thespearfish, bringing it to a virtual standstill andallowing the prey to escape with but littledamage.

It is more reasonable to assume that when aspearfish charges into a school of forage fishthe slashing motion observed by many fisher­men is really a slight changing of directionand a grasping for the fleeing prey, the headand body describing a relatively small arc.Such a grasping motion is not be to identifiedwith any such deliberate slashing as Voss (op .cit.) reported for sailfish. In his observationthe prey was herded into a tight school. Thespeed of the predators was not mentioned.They merely swam into the closely packedschool, held together by the remaining sail­fish (of unreported number), and thrashedwith their spears. Presumably all energy couldbe utilized solely to kill fish rather than beexpended in pursuit.

It must be assumed that spearfish are notalways able to concentrate their prey in suchfashion. In a less dense and guarded schoolof prey, and certainly in a very scatteredschool, it would not be advantageous tomerely slash. It is entirely possible that thenormal procedure is to charge into the schoolrapidly snapping the jaws and reaching, with­in physical limits, for as much prey as possi­ble, with the result that many of the smallfish are killed or wounded before the schoolscatters. Any effective striking with the spearthat may occur is probably a secondary andfortuitous event . After the school has scat­tered the spearfish would likely see thewounded or killed fish and would return toingest them.

These large fishes are obviously built morefor forward speed than for marked agility. Itis entirely within reason to assume that aspearfish can readily overtake any of the for­age fishes or squid , which constitute the bulkof its food, and most of the larger fishes. Aconservative estimate of their speed is at least

67

25 miles per hour and bursts of much greaterspeed are probable. A hooked sailfish wasclocked at 100 yards in three seconds, orapproximately 68 miles per hour (Walford,1937).

The enormous speed and power of spear­fishare dramatically attested by the puncturingof ship hulls. Gudger (1940) reported, withdocumentation and photographs, many spearsfound in wooden and copper-clad hulls ofvessels. Some of these had penetrated fan­tastic thicknesses of timber and had brokenoff to furnish irrefutable evidence of speedand power . One remarkable example follows:"The spear was found to have penetratedthrough the copper sheathing, an inch boardsheathing, a three inch hard wood plank, thesolid white oak timber of the ship 12 in.thick , through another two and a half inchhard oak ceiling-plank, and lastly had per­forated the head of an oil cask, where itremained immovably fixed so that not a singledrop of oil had escaped." This total of 18.5inches through hardwood, 14.5 oEit throughdense oak, was accomplished by a spearfishas the recovered spear was round , unlike theflattened blade of the broadbill swordfish.

SanDiego based wooden-hulled fishing ves­sels have at times been placed in danger ofsinking by these fish. The tuna vessel "RoseAnn " (San Diego Union, 24 Oct., 1946) wasstruck three feet below the water line offPunta Abreojos, Baja California, and wasforced to use both bilge pumps constantlyto remain afloat. Subsequent investigationrevealed five inches of marlin spear projectingthrough the hull planking. Fishermen recalledthat other vessels in 1942 and 1946 had suf­fered the same type of damage. Another re­corded ramming occurred off Ecuador, in­volving the tuna vessel "Renown" (San DiegoUnion, 22 Aug. , 1948). Pumps were operatedcontinuously during the homeward voyage.When the hull was inspected 18 inches ofmarlin spear was found projected through the3-inch hull planking, forming a crack an inchwide.

68

Th ere are furrher indications of the speedand power of marlin, and possibly of theirpugnacity. M orrow (1951) reported havingseen on a beach in British East Africa a bale ofcrude rubber th at held the broken spear of ablack marlin imbedded 8 or 10 inches intorubber so tou gh a man could not drive a spikeinto it with a heavy hammer. Smith (1956)reporred on floating rubber bales from theAfrican coast . As many as four spears havebeen found in one bale. Another bale con­tained 24 inches of the spear of a large blackmarlin embedded to a depth of 13 inches.In one bale was found the sword of a broad­bill swordfish , indicating that it also chargesfloating objects .

The reasons for these attacks are not com­pletely understood. Some may be the resultof sheer pugnacity. However, it has longbeen known that fish often lie beneath float­ing logs, debris, ship hulls or any fairly large ,slowly moving object at or near the surface.The tuna live-bait fishermen make a practiceof fishing, often with considerable success,close to such objects, including th e largewhale shark, Rhineodon typtlSSmith. The ram­ming of ship hulls may well be the result ofexcess speed and a lack of maneuverability ofthe attacker as it charges to engulf fish lyingunder such shelter.

Gudger (op. cit.) supported this view withan observation by F. D . Bennett (Na rrativeof a Whaling Voyage Rou nd the Globe , 1833to 1836, London , 1840). Bennett tells of alba­core [sic], clustering in a dense shoal underthe ship , that "swam with an appearance oftrepidati on and watchfullness. The cause ofthis unusual commo tion was visible . in aswordfish , lurking astern , awaiting a favour­able opportunity to rush upon his prey whenthey shoul d be unconscious of danger oraway from the protecti on of the ship . . . . andin the course of the day we observed himmake several dashes amongst the shoal witha velocity which produced a loud rushin gsound in the sea. . . . It is probable, as aprecaution against the attacks of this rnon-

PACIFIC SCIENCE, Vol. XII, January, 1958

ster, that albacore , and some other tropicalshoal fish, attach themselves to ships, . . . , theclose vicinity of a large body being sufficientto deter the swordfish from making his usualimpetu ous thrusts amidst the shoal ; the which,when rashly attempted, have given rise to theappearance·of the broken rostra of these fishimpacted in the planks of ships, . . . as is notunfrequentl y noticed." Alth ough the name"swordfish" is used it may also have been amember of the round-speared Istiophoridae,as all were termed swordfish until recent years.

Certainly no flailing at prey could have re­sulted in such penetrations of hull s as re­corded. The angle of incidence of spear andhull would eithe r have deflected the spear orhave caused only slight penetration . Also, ifth e spearfish had concentrated on a side-to­side motion, the greater portion of the totalenergy would have been expended in thisaction. The forward speed would have beencorrespondingly reduced, so as to lessen thedepth of penetration, regardless of the angleof incidence . Only a straight-forward chargeresulting from pugnacity or an attempt tocapture prey could result in such pen etrations .

The biolo gical significance of the spearmay well be an adaptation for the great speedand power of these large fish, as well as aweapon of defense or attack. I am indebtedto John D . Isaacs and Carl 1. Hubbs for thefollowing suggestions . A terminally openingmouth would create enormous drag andwoul d push in fron t a mass of water at asimilar speed , so that a spurt of the intendedprey would lead it to safety. If the mouth weretermin al the common mode of ingestion bysuction due to a sudden spreading of the gillcovers as the mouth is opened would prob ­ably be difficult and perhaps dangerous atextreme speeds. On the other hand the pro­jecting and tapered spear would scarcely im­pede the flow of water past the narrowlytriangular mouth on the lower surface of thebase of the beak. A sud den snappin g of thesharply pointed inferior mandible would in­duce minimal drag and would be effective in

Istiophorid Fishes- WISNER

grasping prey . If the spear is of use in feeding,it is probably of most value in permittinghigh speeds to be attained by the feeding fish.

It may be argued that the tunas and por­poises are also rapid swimmers yet have ter­minally opening mouths. However, they tooare well streamlined and have relatively nar­row snouts that no doubt induce minimaldrag at high speeds . Indeed, their spearlessheads may be cons idered analagous to thoseof spearfish without spears . There is littledoubt but that the tunas and porpoises relyon speed to capture prey .

SUMMARY AND CONCLUSIONS

It is concluded that the spearfishes relyprimarily on speed to overtake and engulftheir food . This circumstance explains whyspearless marlins are able to obtain food andto exist in competition with their undamagedfellows. The widely held belief that thesefishes, marlins in particular, normally stunprey with a blow of the spear has presumablystemmed from fishermen watching fish turnslightly to grasp the bait between jaws or toengulf it, during which action the spear per­forms a lateral motion readily interpretable asa slash or blow. The several instances of stab­bings of prey may well have resulted fromthe high speed of the predator and escapeattempts of the prey, the spear point inad­vertantly striking the prey. There is little toindicate that most stabbings are intentional.In the face of preponderant evidence thatmost of the prey is not stabbed, one must,for the present, accept the probability thatsuch spear penetrations are quite accidental.

Further evidence that these fishes rely onspeed to overtake prey are the numerous ac­counts of the ramming of ship hulls andfloating objects. It seems logical to assumethat many such rammings result when spear­fishes charge prey lying under these vesselsand either fail to see the hull or misjudge thedistance between prey and hull. The depthsof penetration strongly indicate that the spear­fish was not using its spear as a flail to obtain

69

food. Such penetrations of objects could haveresulted only from a straight-forward charge,either to seize the prey lying underneath orto battle a fancied enemy. .

The restrictions in rapid lateral movementimposed by the highly integrated and rein­forced vertebral column render it highly im­probable that such fishes normally kill or stunprey by slashing with their spears , particularlywhen in pursuit of fleeing prey. The rough­ened surface of the spear and its relativelyblunt tip preclude the possibility of stabbingthe smaller fishes and the squ id, which com­prise the major food items of the spearfishes.

In whatever way it is used, the spear pre­sumably serves a hydrodynamic function, in­creasing the speed of these large fishes. Infeeding it presumably does more. The formof the spear and of the adjacent parts of thehead seem well fitted to avoid drag, escapeof prey, and possible injury at high speedswhen the mouth is opened. A rapid waterflow is induced past the mouth region, andthe mouth appears to be so formed as topresent minimal resistance when closed andbut slight resistance when opened to seizeprey.

REFERENCES

ANONYMOUS. 19S5a. Pacific Oceanic FisheryInvestigations . Natl. Canners Assoc., FisheryInform. Bul., 22 April, pp. 83-84. Wash­ington.

ANONYMOUS. 19S5b. Feeding marlin usesits head. Internatl. Oceanographic Found.,BuI.1 (3): 38, 39.

BANDINI, RALPH. 1933. Swordfishing. CalifFish and Game 19(4) : 241-248.

BERG, LEO S. 1947. Classification ofFisbes, BothRecentand Fossil.J. W . Edwards, Ann Arbor,Michigan.

FARRINGTON, S. KIP, JR. 1937. Atlantic GameFishing. New York. 298 pp.

- -- 1942. Pacific GameFishing. New York.290 pp.

70

GREY, ZANE. 1926. Tales of the A ngler's El­dorado- New Zealand. New York. 228 pp.

- - -- 1931. Tales of Tahitian Waters. NewYork . 303 pp.

G UDGER, E. W. 1940. The alleged pugnacityof the swordfish and the spearfishes asshown by thei r attacks on vessels. Roy.Asiatic Soc., Bengal Branch, Mem, xii(2 ) :215- 315.

HElLNER, VAN CAMPEN. 1943. Salt Water Fish­ing. Alfred A. Knopf and Co., New Yo rk.

HUBBS, CARL 1., and ROBERT 1. WISNER.1953. Food of marlin in 1951 off SanDiego, California. Calif Fish and Game 39(1): 127-131.

MOORE, HARVEY 1. 1950. The occurrence ofa black marl in Tetrapterus mazara ( J ordanand Snyder) without a spear. Pacific Sci.4(2): 164.

MORROW, JAMES E. 1951. A striped marlin(Makai ra mitsukurii ) without a spear.Copeia 4: 303- 304.

PACIFIC SCIENCE, Vol. XII, January, 1958

--- 1952. Food of the striped marlin,Maka ira mitsukurii, from New Zeal and .Copeia 3: 143-145.

NAKAMURA, HIROSHI. 1938. Rep ort of anInvestigation of the Spearfishes of Formo­san Waters. U: s. Fish and Wildlife Serv.,Spec. Sci. Rpt., Fisheries 153. 1955. 46 pp. , 15pis . Translation from the Japanese by W .G . Van Campen, Pacific Oceanic FisheriesInvest. U. S. Fish and Wildlife ServoHo­nolulu.

SMITH, J. 1. B. 1956. Pugnacity of marlinsand swordfish. Nature 178: 1065.

THOMAS, GEORGE c., J R., and GEORGE C.THOMAS, III. 1930. Game Fish ofthe Pacific,Southern Californiaand Mexico. J. B. Lippin­cott Company, London.

Voss, GILBERT. 1956. Solving life secrets ofthe sailfish . N at!. Geog. Mag. CIX(6) : 859­872 .

WALFORD, LIONEL A. 1937. Marine GameFishes of the PacificCoast, A laska to the Equa­tor. Uni versity of California Press, Berkeley.