27/ ..... " Field Guide to Eastern Pa ci fic and Hawaiian Sharks . UNITED STATES DEPARTMENT OF THE '. FISH AND WILDLIFE SERVICE SH ". BUR EA U 0 F COM MER CI AL .~ ISH ER I ES 11 " .A4467 C; ~ . ~.. U I a r 27 1., no.271 '. " ". ". UNITED STATES DEPARTMENT OF THE INTERIOR Stewart L. Udall, Secretary David S. Black, Under Secretary Stanley A. Cain, Assistant Secretary fO'f Fish and Wildlife and Parks FISH AND WILDLIFE SERVICE, Clarence F . Pautzke, Commissioner BUREAU OF COMMERCIAL FISHERIES, H . E. Crowther, Director Field Guide to Easte rn Pacific and Hawaiian Sharks By SUS UMU K A TO, STEWART SPRINGER , and MARY H. WAGNER Circular 271 Washington, D.C. December 1967 CONTENTS Page Introduction•..••. 1 How to use the key. 1 Key to families of eastern Pacific and Hawaiian sharks. 2 Frill shark, family Chlamydoselachidae •.•••• 5 Sixgill and sevengill sharks, family Hexanchidae • 5 Bullhead sharks, family Heterodontidae •. 7 Squaloid sharks, family Squalidae . 8 Ange l sharks, family Squatinidae .. 14 Nurse sharks, family Orectolobidae .• 15 Basking sharks, family Cetorhinidae • 15 Sand sharks, family Odontaspidae .. 16 Thresher sharks, family Alopiidae 17 Whale shark, family Rhincodontidae • 18 Mackerel sharks, family Lamnidae . 19 C at sharks, family Scyliorhinidae ••. 22 Hammerhead sharks, family Sphyrnidae •• 27 Smoothhounds, family Triakidae ••••••• 30 Requiem sharks, family Carcharhinidae •• 35 Acknowledgments. •••••••••...••• . 46 References .•.••• . 47 Field Guide to Eastern Pacific and Hawaiian Sharks By SUSUMU KA TO, Fishery Biologist 1 and STEWAR T SPRINGER and MAR Y H. WAGNER , Biologists 2 ABSTRACT Illustrations , descriptions, and keys tothe identific ationofmore t han 70 speCles of sharks are presented. INTRODUCTION Our purpose is to provide a useful field guide to the identification of all the sharks known to occur in the vast s eas of the eastern Pacific from Alaska to Cape Horn, and in the waters sur­ rounding the Hawaiian Islands. An illustrated two-stage key is used to separate h e species . Nearly all of the species are illustrated; specimens collected especially for the preparatIOn of this guide w ere the main source of material, but some specimens we r e also borrowed fron­ m useUInS. Drawings of a fe w rare species of which specimens were unavailable were b.J.sed or. published or unpublished photographs. The reader should refer to the illustrations for verlhca Ion of identification from the key, but it should be remembered that many sharks change III body cmd fin proportions with growth, and that color patterns of some sharks are variable . ,'otes ~nd descriptions which are given for each species also serve as additional criteria for verlfy:r." identification. The s c ientific name is given for each species , and, for many, common names in Er.gllsi. 0r Spanish are also given. U s age of common names v aries g reatly, especially from coun ry to country. We have used common names recognized by the American Fisheries Society chcd':I~t (1960) whenever applicable , but new names have been selected for a few 3pecies, e . iZ .• " pepp,>:-ed shark" for Galeus piperatus. We have tried to retain the scientific names now in general use but at t he sarre tln-t-! r. .J.ve attempted to keep names in line with current studies. Some of these studies are s III unpubll~;"ed. We have neither included synonymies nor stated our reasons for the inclusio n or exclus.ol' of certain species that have been recorded from the eastern Pacif ic and Hawaii. F or ex.urr l' , we have used the name CephaloscylliUIn ventriosUIn Garman, lSSO , for the swell s ha rl<s of • '1 North and South America, excluding the name C. uter Jordan and Evermann, ISC, • whlc~ - , customarily been used for the northern form; ourdecision here was based on descriptlOr." r:Vt" in published accounts, in which we did not find differences between the two forms. HOW TO USE THE KEY Although many of the species listed in this guide are found in other par s of he ,vor.d , t;.e keys will not be suitable for identification of s har ks outside the eastern PaCific or r.e v'C:l'.:'v of the Hawaiian Islands. Diagram s of the shark's external fe ature s (figs. I and 2) are lncluded to define errrs used in the keys and to indicate methods of measurement. With t he unidentified shark specimen at hand, refer hrst to t he key to famllies and be :1' by reading both la and 1 b (both phr ases in each c ouplet should be read dUrln12 he e nt: re :der.t.­ fication procedure). Select the phrase that describes the specimen and continue 0 the nex dp ­ propriate couplet until the family lS determined. The succeeding couplet IS llldica ed by 'n .. 1 Bureau of Commercial Fisheries Tuna Resources Laboratory. La Jolla, Calif. 92037. 2 Bureau of Commercial Fisheries Ichthyological Laboratory, Stanford, Calif. Q430 5. L------ - --TOTAL LENGTH - - -----------1 ~NOUT TO FI RS~ DORSAL FI N I I' DORSAL F I N I I I SNOUT TO EY E I k-Lj ~---...I I ,SPI RACLE ~ . \((-GILL SLITS FI N POSTERIOR LOWER CAU DAL CO RNER LOBE PELVIC F IN PE CTOR AL FIN Figure l.--Outline drawing of a shark showing exte rnal features and methods of measurement; no single s hark possesses all the fea tures s hown . hgur es on t h e right side of the page. F or example : if t he s pecimen ha s six or s even gill slits lnst ead o f five, 50 to couplet la- lb; if it ha s five gill slits, go t o 3a- 3b. For the sev eral s p ecies that are the sole members of their families, identificat ion is com pl ete at this point. Descriptions aj-d illustrat i ons of t hese species are given in t heir resp ective fami ly sections. If t he family is represented b y more t han o ne easter n Pacific species, the n ext s tep is t o turn to the approp riate family section and again begin the process of sel ect ion unt i l t he s p ecies is d etermined. KEY TO FAMILIES OF EASTERN PACIFIC AND HAWAIIAN SHARKS I a . Sharks with six or seven pairs of gill slit s l a o r l b I b. Sha r ks w ith five pair s of gill slits ... 3 a or 3b la . First gill slits unusually well devel oped, fi r s t pair c o nt inuous i n a fol d across m i dventral line; teeth of upper a nd lower jaws simila r in s h a pe .... .• • •. •.•. • . • ... ..•••. • • . • . • . • . .. F r ill s hark , Fami l y Chl amy doselachidae, p . 5 • lb. First gill slits not unusually w ell devel oped, fi rst pair not continuous a c ross midve n t ral line ; teet h o f upper and lower jaws dissi m ilar in shape .. • • . .. •. • . .. .• ..•.•. Sixgill a n d s e vengill sharks, Family Hex anchidae, p . 5 • 3a. Anal fin absent. 4a o r 4b 3b . Anal fi n present 5a o r 5b -tao Trunk fla ttened, raylike; eyes on top head ... • Angel sharks, Famil y Squat inidae, p . 14 . -tb. Trunk cylindric al or nearly s o; eyes on sides o f h e ad . .. .. • • •.•••. • . •...• • ...• Squal oid sharks , Family Squalidae, p . 8 l A SNOUT LENGTH ~ I .. I OUTER LABIAL GROOVE I INNER LABIAL GROOVE I r- MOUT H WIDTH ~l INTERNASAL DISTANCE B FRONT MARGIN REAR MARGIN DORSAL FIN FREE REAR TI P BASE--b~ LENGTH OF FREE REAR TIP c BASE SECONDARY CUSP SERRATIONS "";'-CUSP Figure 2.--0utline drawings of parts of a shark showing terminology and methods of measurement: A - Underside of head; B - Dorsal fin; C - Tooth. 3 5 A hard pin in fron of ch dore 1 fin . .. ullh d h rk • m l' H rodo p. 7 . 5b. o spin in [ron of do r. 1 fLn or b ------ 6a . l\louth n rly at forw I'd nd of h d 6b . Iou h on lower It.! o f h .Id Ith • ou ( ron o C mo\,l h. 7 or 7b 7a . Ongin of first dol' al (m h d o C o C elr n ver r ;}ch to point. bov ... if.,. Onpn . or , IC orl dor al r nd o f b • dorsal Sa . Fleshy barb PI' 'nt on Inn I' Id of ,eh . I, F mll' Or c o ob d lS . fl ", ~ y b ,\ r bel r a ron! ( F mt.y SC)'lIor lrud . p. ... l . ~a. Lt:n~th of cauddl fm abou 'ql.al 0: n h 0 body I"h r r r • rk . F mll Ao td , p. 17 . 0b . Length of caudal Ctn much .. hor r .r lcn h of bod ' . lOa or lOb lOa. Caudal iln crescentiC , upp,r lobr' [1(Vrr mor h n I. 1m nor ob II or lib lOb. Lpper lobe of caudal fIn more h n ',"1 C • 10 10 r lob • ("r 0'" r ob r.c Ilb Ila . Teeth minute , about 200 In iron en of upp r Jaw; III II v r lon , Cr om high on dorsal Ide 0 near h mldlln on "en fal lid Oa kin Iha rk Famtl . C orhllud • p . IS. 11 b . Teeth 1.1 rgc, about 25 o 35 In fro erte of upper Ja; 11 11 lon , bu co Ined 0 Sides of head . • tacker 1 hark . Family Lamnidae, p .