CORE Metadata, citation and similar papers at core.ac.uk
Provided by NSU Works
Nova Southeastern University NSUWorks
Oceanography Faculty Articles Department of Marine and Environmental Sciences
10-1-2004 Evidence of Shark Predation and Scavenging on Fishes Equipped with Pop-up Satellite Archival Tags David W. Kerstetter Virginia Institute of Marine Science, [email protected]
J. Polovina National Marine Fisheries Service - Honolulu
John E. Graves Virginia Institute of Marine Science
Find out more information about Nova Southeastern University and the Oceanographic Center.
Follow this and additional works at: http://nsuworks.nova.edu/occ_facarticles Part of the Marine Biology Commons, and the Oceanography and Atmospheric Sciences and Meteorology Commons
NSUWorks Citation David W. Kerstetter, J. Polovina, and John E. Graves. 2004. Evidence of Shark Predation and Scavenging on Fishes Equipped with Pop- up Satellite Archival Tags .Fishery Bulletin , (4) : 750 -756. http://nsuworks.nova.edu/occ_facarticles/542.
This Article is brought to you for free and open access by the Department of Marine and Environmental Sciences at NSUWorks. It has been accepted for inclusion in Oceanography Faculty Articles by an authorized administrator of NSUWorks. For more information, please contact [email protected]. Nova Southeastern University NSUWorks
Oceanography Faculty Articles Oceanographic Center Faculty Publications
10-1-2004 Evidence of Shark Predation and Scavenging on Fishes Equipped with Pop-up Satellite Archival Tags David W. Kerstetter
J. Polovina
John E. Graves
Find out more information about Nova Southeastern University and the Oceanographic Center.
Follow this and additional works at: http://nsuworks.nova.edu/occ_facarticles Part of the Marine Biology Commons, and the Oceanography and Atmospheric Sciences and Meteorology Commons
This Article is brought to you for free and open access by the Oceanographic Center Faculty Publications at NSUWorks. It has been accepted for inclusion in Oceanography Faculty Articles by an authorized administrator of NSUWorks. 750
Evidence of shark predation and scavenging on almost swallowi ng a free-floating PSAT off the Dominican Republic in fishes equipped with pop-up satellite archival tags Muy 2002 (Graves, personal obser v.). Alternately, the tag could be ingested David W. Kco:t e tter incidentally with part of the tngged fish , as described by Jolley and Irby School 01 Marine xience (979) who reported that a n acoustic Virginia Institute of M,mne S(lence College of William and Mary tag on a sailfish (lstiofJhorll s pLotyp. GIouc~ler POint. Virgima 23062 tcrus) was eaten a long with the fish
E nvol ~rHS b.I~ fi: VI01S Mu by an undetermined species ofshnrk. In this note, we present data from PSATs deployed on two white marlin Jeffery J. Poloyina in t he western North Atla ntic Ocean POK ilk Islands Fisheries xlence Cenler and on nn opah (Lampris gul/alus) NaTional Manne Fishenes ServICE' in the central Paci fic; the data from Honolulu, Hawaii 96822 these tags indicate that the tags were consumed by sharks. John E. Graves School of Manne SClefI A:t approximately 10:00 am local time on I September 2002, a wh ite marlin was obser ved on pelagic longline gear set dul"ing the ni ght near the Over the past few years, pop-up sat have developed mecha nisms t hat reo southenste r·n edge of Georges Ba nk. e ll ite u l'chival tags ( PSA'l's) have lease tags from dead or dying fi s h The fish , which had been caught been used to investigate the behav before the struct ural integrity of the on n s lightly offset, s t ra ig ht·shank ior, movements, thermal biology, tag is compromised at de pth. These J ·style hook (size 9/0 ). wns manu· find poslrcicasc mortality of a w ide mecha ni s ms include both mechani ally guided with the leader a long range of la rge, highly mig ratory s pe cal devices that sever the monofila side the vessel. A PTT-lOO H R model cies including blucfin luna Table 1 Cornp" I'i ~O Il of depth s n nd tern perntu r e ~ recurded by t.h reI.' pop-up satellite (lI'ch i \';11 t;lg~ (PSA 'l's) bl.'fol'(l n lid ;1he r t he tags were ingested by an oq:,an ism. Before ingestion Aftel' ingestion Depth Depth Temp. Tl.'rn p Depth Depth Temp Temp rnnge Illl.'all ra ngl.' nll.' an ra nge mean range mean Anirnnl ( m) ( SD> ( C, (SO) " ( Ill ) ( SD ) t·C) ( SD ) " Wi'll I 14;'.2 1,15.2 11.6-11 1 1.7 17!) 0-564.9 130.0 12.1-26.5 24.1 2755 ( ~O . OO ) f ~ 0 . 0 7j t~237. 50 ) b:0.84 ) W;\12 0-26,9 5.9 19.8 -27.8 2,1.7 207 0 - 699.=1 13 1.0 18.9 - 29.5 27.3 1683 ( ~ ' I A4 J I ~ 0.9 ]) 1:!: 162.611 (:!:1.20 ) 32- 456 221.81 8_·-,J - .6 Hi68 360 0 -52<1 170.56 26.2-30.6 28.64 168 1~92 .2 0 J (:= ,1. 211 1:!: 1=13.83) (:!:0.67) ttlgs, mlllllllUrll stra ight-line distances were calculated the dorsal musculaLuI'e wi t h a Wildli fe Compute rs tita bet ween the point of release nnd t he firs t clearly trans nium a nchor. The tag was I)rogl'ammed to record t he mitted location of t he t ag follow ing its re lease (pop-of 0 tempera ture a nd depth occ upied by t he fi sh in binned (Argos location codeS 0-3). histograms. a nd the m inimu m a nd maximum teml)era At the time of taggi ng. the longl ine hook used to Cal) Lur'es a nd depths fo r 12-hour time periods. Howeve r, tUl'e t he fi sh was not vi sible in the mouth of t he whi te t hes e 12-houl' bins e ncompassed bot h day a nd nig ht marl in. The leader was therefore cul tiS close ar; possible pel'iods. The tag was prog rammed to be released s ix to t he fish before the fi s h was r·e leased. following the months aftel' deployment. In the event of a premature standa rd operating pl'oeedu re fOl' the domestic pelagic release. lhe tag was pl'ogrammed to begin t ransmitting lon gline fleet. T he fish was maint a ined alongside the stored data if it rema ined at the s\lrface for longer than vessel for less t hun three mi nutes for t he a pplication of th ree day s. The opa h wa s lively a nd qu ick ly dived after the PSAT a nd a conventiOll(ll streamer lag. Al though the it wa s released. white marl in was initially active at t he side of t he vessel. some light bleedi ng from the gills wa s noted. After re lease, the fi s h swam away s lowly unde r its own powe r. Resu lts White marlin 2 (WM 2) WM I At 9:05 a m on 2 August 2003. a white mal'lin was Release of the PSAT was expected to occur on 10 Sep obsel'ved on I)elagic longline gea r with the same configu tember 2002 a nd t he tag was expected to begin transmit ration in t he same apl»'oxi ma te area or Georges Ba nk as t ing data on that date, but the fi rst t rans mission was W)'11. The fi s h was caught by a circle hook (size 16/0 ) in not I"eceived until a lmos t t wo days latel". At t he t ime of t he ri ght corne r of t he mouth, and a lthough t he stomach firs t trans m ission. the PS AT waS 8 1.3 km (43.9 n mil was e ve rted. the fis h a l)l)ea.'ed to be in excellent ph ys i ~ west-southwest of t he laggi ng loca tion. A tota l of 8 1.5';} cal cond ition. A P'I'T-100 HH t ag had been activated a t of t he a rchived light level. Le mperature, a nd pressure 6:30 a m that morni ng. and was tberefor'e col lecting data (depth) datu was recovered. at t he t i me of tagging. Arter the fi s h was brought to t he The light level. tenl!)erat\l l"e, a nd pl'esSu re (depth) s ide of the vessel, both the PSAT and a conventional I'eadings over time a rc presented in Fig. 1 (A-C) and streamer tag were a ttached to this fi sh in less than three SUrllmarized in Ta bl e 1. The fi rst light level measure minutes by us ing t he same Pl"otocol as that described for ments indicated that the fi s h was al ready in relatively Wl\'Il , and t he fi sh swam strongly a way f.-om t he vessel da rk wa ters within one houl' fol lowing its release. Light after r'elease wit hout any evident bleed ing. levels cont inued to d rop to al most zero du ri ng t he ne xt ten hours a nd remained at t hat level ror the ne xt ni ne Opah days (Fig. IA ). During t he ne xt seven.day s urface t rans mission period, the tag recOl'ded r'eal-time day a nd night At 5:52 pm local time on 2 1 November 2002, a female differe nces in lig ht level s, which indicated that the light opa h wa s observed on pe lagic longline gear set du ring sensor was functioning properly. the day cast of the Is land of Hawuii. The fish was brought Sea su rface tempe l'El Lul'es in t he a rea whel'e the gea l' to the s ide oflhe fis hing vessel a nd a Wildl ife Computers wtl S set and IHlul ed back , varied from 25.20 to 26.7°C (I{cdmond, \VA ) PAT2 model tag wa s attached ttHough (D. Kerstetter. unpubt. dat a ) and the fi rst temperat ure 7S2 Fishery Bulletin 102(4) A WM l D WM 2 • II E - .. .. " " c -- r - F .. , .. .. " Figure 1 Graphs ofdntA on and depth (A and OJ. temperatu re (8 a nd E). lind light index (C and .' ) for tags WMI and WM2. Lighter lines and points arc prior to programmed r cJea~e date, whereas darker lines lind poinls arc "real·lime" s urface condition measurements t ransmitted by the tag in addition to the a rchived data. recording by t he PSAT (one hour after activa t. ion) was ment bet ween t he s urface and depths to 565 m . T he 11 "C (Fig. 18). The temperatu re rema ined fai rl y con t ag was at the surface when it began transmitting bot h st a nt at I l"G for a per iod of approxi mately ten hours a rchived and r eal-time data on 12 September. a fter wh ic h t here was a ra pid r isc to 25"C. The temper ature of the PSAT remained between 22.5° a nd 26.5 Q C WM2 for the next nine days (u ntil t he programmed release date), with the exception of one brief decrease to 20<> C The tag repor ted data as expected on 13 August 2003 on 8 Septembe r. When t he t ag began t ransmitting on a nd transmitted 57.3% of t he a rchived data. At the time 12 September, the rea l·time s urface temper ature wa s of fi rs t t ransmission. t he PSAT was 600.1 km (324.0 23.6<> C. I1 mj) cast -southeast of t he tagging location. Sum mary The pressure data (Fig. IC) indicated that the tag was dept h and tempe rat ure data recorded by the PSAT arc at a dept h of a pprox imately 14 5 m at one hour follo wing included in Table l. relea se. T he PSAT remained at this depth for a lit tle From t he depth and temperatu re data, it appears more tha n te n hours a fter which t he data suggested that the fish survived for approximately 24 hours a f that there was a rapid rise to the s u rface. For t he next ter release. at which poi nt the light readings dropped ni ne days, the tag repol·ted considerable ver t ical move- to zero (sec F ig, 10) a nd re mained at that level fo r NOTE Kerstetter et al. : Shark predation and scavenging on fi shes equipped with sa tellite archival tags 753 the next e ight dnys. T he depth record fo llowing this change in light level was marked by several Dive minimums and maximums discre te diving events, a nd depths (sec Fig. 1 F) , ra ngod betwoen t he surface and over 699 m. Hocordod tempe r atu l·es for this period varied "" ~ between 18.9° a nd 29.5°C, although sea su .-face E te mpe ratures in the a rea where gear was set and -0 "'" 0 li hauled back varied from 20.9° to 26.0 e (Ke r a• s tetter, unpub\. data). On 12 Augus t. t he light "" level returned to its maximum value and the lag "" I·c mai ned at the s u r face fo r a pproxi mately one day until its scheduled release date (13 August ) when it began t ransmitting data. 1 1/24102 1 1/30102 1216102 12112102 12/16102 12124102 Opah Oive minimums and maximums T he PA'I'2 su teJl ite tag was eX I)ected to pop· up 28 6 month!; after deploy ment, but the first tra ns ~ mission was received after only 34 days from a u• " loca tion about 330 km (178 n mi) nonhwest of t he -•, del)loymc nt site. All the archived binned light ,- " level. t e mperatu re, a nd pressure (depth) data ~ " from this per iod were recovered (sec Table 1). E ~ This tag model collected eight temperature and " del)th samples dU I·ing each 12-hour pe riod, result· ing in 16 values pe r day or 528 total values for the de ployment period. The two 12-hour blocks were re moved from all a nalyses to more Ilceu· light minimums and maximums from location data nltely re pl·cscnt the differe nces in data between specimens: !) t he 12-hour block after tagging in order to allow fo.· the I·ecovery of the anima\. and 2 ) the 12-hou r block during which the prcdation • "'" event putatively occurred in orde r to cla r ify thc ~ •> '" I)otentiatly distant depth a nd te ml)eratu.·e cha r 0- acteristics of the ingesting animal. :3' '" . . The measured sea s urface tempe rature du r ing , , ' I . I , • the taggi ng of the opah was 25.9°C. The ra nges " of di ve depths , te mperature, and light based on , minimum lind maximum values over the 12-hour 11 /24/02 l1r.)O,1Q2 12/6102 12/12102 12/18102 12124/02 day and nig ht pe r iods showed two dis t inct pat Date te rns (Fig. 2 ). During the fi rst period (23 d ays), Figure 2 the dive depths ra nged from about 32 to 456 Graphs of depth ( A ). tl!mperalure ( 8 ). and light index (e ) for m ( Fig. 2A). Water temperatu res encounte red the Ol)ah PAT t a g frOIll de ployment until t ranSllIission. by the tag during this period ranged from 8.0° to 25.6°C (Fig. 2B) a nd the light index va lu es ra nged from about 50 to 150 ( Fig. 2C). During the second period (11 days ), the dive depths ranged from recorde d a bout one hour a fter its release, ind icated o (.0524 m, temperature ranged fl·om 26.2° to 30.Goe that the marlin was a lready d ead or moribund by (h ig he r t han the 24.2-24.8°e SST recorded by t he tag t hat time and was descending to t he ocean floor. For a fter it was released from the fi s h ), and the lig ht index the next ten hOllrs , t he t ag and carcass re mained at recorded persistently low values. a constant depth of 145 m (the de pth of t he nea rest sou nd ing at the !o: ite of relea!o:e, according to NOAA depth chnrt 13003 119981. was approximately 160 m) Discu ssion and at a tempe r at\1n~ of I loe. The light level s tead ily decreas ed at approx imately 4:30 pm, corres ponding to WM' changes in ambient li ght from t he setti ng of the su n, At a pproximately 9:00 pm loca l t ime, there was a dra Our interpretation o f t hese d atH is t hat t he PS AT matic change in conditions when tempe r ature rapidly on WM I was ingested by an anim nl scaveng ing the rose to ne al· 2WC a nd de pths began to vary be tween ma rl in ca rcass. The firs t PSAT read ings fo r WMI , t he s urface and 600 Ill. 75< Fishery Bulletin 102(4) We cannot a t t ribute t hese cha ng es to 11 resuscitation of t he fish for 2~ . O , three reason s. 1) The measured light. •• ••• " '00 levels indicated that t.he tag was in ~, • •• .. complete darkness for a period of ten • .. u •• \ days, even though it was at the sur -• no .. • • face during daylight hou rs. A mal -, • , • n> •• • \ functioning li ght. sensor cannot ex -•• • ,.. plain this obser vation because the tag & E • recorded day and night diffe re nces no \ I' ... _ Temperature in light levels at the s urface during _ Depth the seven-day transmission period a f 21 .5 ter it was released from the fi sh. 2) After a ra pid increase, the tempe ra 21 ,0 •.» , ture rema ined rela tively cons tant, '" .. between 230 a nd 26°C, even when local time the tag was a t de pths in excess of 300 m. Alt hough dive behavior may Figure 3 be affeu ed by location,speci fi c con· Delayed temperature changes recorded by t ag \\1 M I follo wing deep dive di tions, previous PSAT observations events on t he mor ning of 2 September 2002. Arrows indicate the lowest of more tha n 20 ot her white ma rl in temperatures recorded in association with a mO\'ement of the a nimal to indicated t hat temperature ra nges of depth; note that these temperatures we re of tel} recorded while the animal ind ividual dive events rarely exceed wall at or ncar t he s urface a nd t herefore represent 11 delay betweell depth and temperature. 8°C when, it is assumed , un ima ls ma ke foraging dives to depth (Horo· dysky el a I., in press). 3) The PSAT recorded several dives in excess of 400 m, a nd previous attacked t he opa h and ingested the tag incidentally, observatio ns of white mar li n have revealed no d ives in or 3) an ani ma l ingested the tag a lone. However, it is excess of 220 m ( Horodysky et aI., in press). Finally, unlikely that the opah died, sank to the ocean 1I 00r, a nd the PSA'i' was scheduled to be released from WM I after was scavenged because the ocean lloor in the a rea where ten days on 10 September. Although archi ving of light, the opa h was tagged is below 2000 n1. We have observed temperature, a nd pressure duta ceased on that date. t he from other tags on opahs what we believe arc mo rtalities; tag d id not begin t ra ns mitting u ntil 12 September. t hese occur shortly after tagging and s how that t he tag reaches depths in excess of 1000 m before detuching when WM2 the emergency pressure release in the tag is triggered. We did not observe depths below 600 m at a ny time during The s ha llow dive patterns reported by t his fish may this record, and therefore t he pressure.i nduced detach· indicate that it survived fo r a pproximately 24 hours ment mechanism on the tag was no t trigge red. following its release. Bet ween 12:45 and 3:07 pm (local The ingestion hypothesis for the failure of t hese t hree time), the light level fell abruptly fro m the maximum tags to t ransmit data is supported by several lines of light level value to zero. At 3:08 pm, t he temperature evidence. Fi rst, the light level rendings wel·e consistent was 19.8°C at 166 m depth: by 4 :37 pm, t he teml)era wi t h a tag residi ng in the complete da rkness of an t ure was above 24°C and remained a bove this value fOI· a limentary cana l. Second, although temperatu re va ria the remainder of the deployment period. At 5:58 pm on tions occurred during the deployment period, t he delay 12 September, the light levels returned to max imu m in temperature changes during dives to dept hs indicates s t rengt h from zero- a n ind ication t hat the tag had t hat the tags were not di rectly exposed to ambient wa likely been egested. For the 19 hours remain ing of the ter (sec Fig. 3 for an example from WMI, as well as t he prognlrn med deployment period prior to pop·off, t he comparisons in Table 1) and further may indicate t hat del)th, light, and temperat ure data all ind icated that the scavenger was either endothermic or of la rge enough t he tag was floa ting at the s urface. si ze to mitigate heat loss at depth. There a rc severa l organisms that cou ld have eaten Opah these PSATs, whether by scavenging a carcas!; or at tacking a moving fi sh. Clearly, each of these organisms Based on recovered data, our conjecture is that t he tag was s ufficiently large to ingest the tag without ser io was attached to the live opa h for t he fi rs t 23 days. Then, ously damaging it. It is unli kely that a cetacean was sometime during the 12 ·hour period from 2:00 pm 13 res ponsible fo r any of these events because inter nal December to 2:00 a m 14 December the tug was ingested. temperatures for odontocete wha les (includi ng killer From OlL r data, we cannot discern whether 1) the tag wha les, OrcillU s orca) range between a pproximately 36° was detached prematurely fro m t he opah and was 1I0at and 38°C (Whit tow et a I., 197<1 )-well above the range ing on the surface when it was ingested. 2) an a ni mH I of temperatures recorded by the PSATs. NOTE Ker stetter et al. : Shark predation and scavenging on fishes equipped with satellite archival tags 755 T h £! only other natural preda tors of la rge Il elag ic s tomachs. Econol1lakis a nd Lobel (1998) also s tated fi shes a rc various species of sharks. Sevel'al species of t heir belief that regurgitation of ingested ultrasonic lumnid s harks maintain elevated body temperatures. tags was the pri mary cause of los t t racks for grey reef including the shonfin mako (lsl/rus oxyr;III: /III" ) and the s harks ( Cllrc"arhillu .~ lllllblyrhYllchos ) on Johnston Atoll white s hal'k (CardlDlYx!oll can; haria.~ ) , both of which a rc in the centra l Pacific Ocean. found in the a rea of Georges Ba nk (Cramer, 2000) and the Central Pac ific (Compagno, 1984 ). Several shortlin ma kos were caught by the same longline vessel during Conclusions the week fo llowing each white marlin PSAT deployment (Wl\Il : 11 =4. 95-189 cm FL: WM 2: 11=3. 94- 199 cm FL) The temperatures and dive depths recorded by the opah (Kerstetter. unpubl. data), The opa h tag record closely tag a nd both white marlin tags after apparent ingestion resembles the relatively constant temperature noted for sha l'e sim ilarities. yet a lso con tain sufficient information bmnid s harks, des pite the independence of stomach to indicate the different identities of the ingesting OJ'gan temperatu re wi th ambient water for these endothermic isms. The dive dellths in all cases ranged from t he s urface s h :'Hks as l·epol·ted by Carey et n l. (198 1), It is also to over- 500 m, whereas the temperatures remained rela in teresting to note that although 1)I'ecipilollS tempera tively constant at sevcral deg rees above the background ture flu auations were generally absent. a rapid drop in SST. even during decp dive events. Temperature ranges tempe l'uture fl'om 24" to 20"C was observed with tag alone strongly indicatc s harks rather t han odontocete WMI on 8 September at 32.3 m de pth- a fluctuation whales were the ingesting organis ms. However, limited that could have resulted from another fc t'! ding event literature on the internal stomach temperatures of the that brought cool food matter in to the stomach. Simi variou s pelagic sharks fo rces us to rely on telemetered la r reductions in s tomach temperatures due to feeding diving behavior data for further species identification. have been noted fOl" white sha l'ks ()'1 cCoskel-, 1987). The which we used in the present study to suggest that blue range of temperatures recorded by each of the t wo white sharks ingested the two white ma rlin tags (on account marlin tags appears rather brond for an endothermic of the broad ra nge of recorded temperatures) a nd t hat shark. however. and although the temperature at depth a n endothermic shark ingested the opah tag. was not llleasu l'ed. the delay in s tomach temperature It is not possible to account for all of the factors that closely resembles t he pattel-n of blue s hal'k intetlwl may res ult in the fa ilure of satell ite tags to t r'ans m it temperatu l'es (PriOIl(l ce glauc(l) measured in the 1\'l id data, but the res ults from these th r'ee PSATs indicated Atlantic (Care), and Schal"Old. 1990). thut biological activities s uch as predation and scaveng The divi ng behavior recorded by the th ree tags al so ing may play an important role. We believe that the corroborates ingestion of the tags by s harks. Carey et al. mos t consis tt'!n t ex planation for the data t ransm itted (1982) reported that a tagged white shark off Long Is· by these th ree tags is that they were ingested by large la nd. New York , made frequent dives to the bottom dur s ha rks. One cannot calculate the probability that a ing :l 3.5 -day acoustic tracking I>c r iod, White sharks arc tag could be engulfed whole without physica l damage known to dive to depth while scavenging whnle carcasses to t he tag, s urvive fo r several days in the ca ustic en (Dudley et a I. , 2000: Carey et al.. 1982). A juvenile white vi l'on ment of a digestive sys tem, a nd be regurgitated s hatk also tracked by Klimley el al. (2002) s pent fat with s ufficient bauery power to t ra ns mit data to the more eXLCn ded times at depth than either white marl in Argos satell ites. but we s us pect that the probability is tag, Although the programming of the tag on the opah not very greal. We expect that a far greater number of precludes such fine-scale analyses of diving behavior. the tags may have had si mil ar fates, that is to say. they ava ilable duta a rc not inconsistent with the mako tracks were damaged by predation or scavenging and digestion in the s tudy of Klimley et al. (2002). However. the shott processes or wel'e l'egurgitated later in the transmis duration dives with frequent returns to the surface seen sion cycle. when t he PSAT batter'ies had ins uffi cient with the two white madin tags most closely resemble remaining power for successful data transmission. The those of blue sharks (Carey and Scharold. 1990) and failure of satellite tag to t rans mit data is frequently were notably missing from the tracks of th ree shortfin considcl'ed to be the result of internal tag malfunction ma kos observed by Klimley et al. (2002 )_ or user e rr-ot, Howeve r. these three data sets clearly Ir s harks were indeed the scavenging a nima ls. it ind icate t hat the failu re of PSATs to function may also is likely that the tags were regurgitated. rather than be due to predation or scavenging events. eges ted through the a limentary ca nal. whereupon t he PSAT fl oated to t he su rface and was able to transmit the nrchived data. The narrow diameter of the spiral Acknowledgments valve in the elas mobranch gasttoinlesti nal tract would li k£! ly be too na rrow to allow the undamaged passage The authors would like to thank the Captain of the FV of a n object t he size of a PSAT, even for a la rge sha rk. Sea Pearl and Captain Greg O'Nei ll of the rv Carol AIIII, Although the available literatul'e describi ng regurgita Don Hawn (University of Hawa ii). who de ployed the tag tion abilities of pelagic s harks is t ather limited, Hazin on the apah. Evan Howell (PIFSC) for analyses of the et al. (]994 ) reported t hat 35 '11 of blue s harks brought opah data, Andrij Horodys ky (VIMS), who provided a aboar'd fot scientific st\ldy had evel-ted and Pl-utl-ud ing critical review of the manuscript , Melinda Braun (Wild, 756 Fishery Bulletm 102(4) life Computers), who suggested t he pl'cdation hypothesis white sha rk s. Carcharodon mrclwrwtl. and tiger sharktl. to cxplnin the opah data. and Li ssa \Verbos (Mic rowave Gofeocerdo Cll llicr. ~' i s h . Ilull. 98:646- 649. Telemetry. Inc. ), who independently s uggested the scavo t: conomakis. A. E .. and P. S. Lobel. Cor. enging hypothesis for the Wi\U dnta. This research WfiS 1998. /\ ggregation behlwior of the grey reef shark. c hflrhiIHl.~ flmblyrhynchos. at Johnston Atoll . centr!!! sUI>portcd in pan by the Nutionnl i\h\ri nc Fis hel'jes Pacific Ocean. fo:n\-iron. BioI. Fi shes 51(2 ): 129- 139. Service. t he NOAA Ocean Exploration Program , a nd Onlves. J . E .. 13 . E. Luck hurst. and 1-:. D. Prince. t he Un iversity of Hawaii Pelagic Fis heries Hosonl'ch 2002. An evaluation of pop·up satellite tags for estimating Progrnm (PFRP). post·release sUT\'h'al of blue marlin (M akai ra nigrico,,,,) from a recreational fi shery. fo·ish . Bull. 100:134-142. 1 · l a~in. F.. R. tessa. lind M. Chllm,nlls. Literature ci ted 1994. First obsen'ntiOIl S on li tomach contents of the blue shark. J>Tl O llf/ C~ 8lmlca. from southwestern equatorial ;\tlantic. He\'ista Ilrasileira de Biologia Block. U. A., H. Dewar. S. B. BlfH:kwcll. T. D. Williams. 54 (2 ): 195-198. t;. I), Prince, C. J. Farwell, ,\ , BOUMany, S. L. H. Teo, Ilorod)'sky. A. Z.. D. W. Kerstetter. and J . E. Gra\·es. A. 501 17. . A. Wnlli. and D. Fudge. In press. Habitat I'rcrerences and di ving behavior of 2001 . Migratory movements. depth preferences and while martin (Tetral'llIrlllf II/bidlltl) relensed from the thermal biology or Al irwlic blucrin LU na. SCiC I1 CC re<: realional rod·and·reel and commercial pelagic longline 293: 1310- 13 14. fi sheries in the western North Atlantic: im l)\icationH for BoustlU1Y.I\ . M., S. F. On,'is. P. Pyle, S. D. f\ nderson. habitnl·based stock ll 88eHsment models. Internationnl 13 . J . t.elm of. ~lnd B. ,\ . Ulock . Commission for the Conserva tion of Atlantic Tunas. 2002. Expanded niche fo r white sharks. Natore 415: Coli. Vol . Sci. Pap.. SCRS 2003/033. 35-36. J olley. J . W.. Jr.• and E. W. Irby Jr. Cnr'<'y. fl. G.. J . W. Kanwisher. O. Ilrazier. G. Gabrielson. 1979. Survival ortngged a nd released Allalllic sailfish J . G. Casey. and H. I.. Prall. (l sI ioplwrutl pfa Iyplcru If: 1st iophoridae) determ i ned "" ith 1982. Temperature and acth-ilies of n white shark. Car· IIcoustical telemelry. Bull. Ma r. Sci. 29(2 ): 155-169. dwro(/olI corc/'orioll. Copein 1982(2 ): 254-260. Kerstetter. D. W.. B. E. tuck hurst. K D. Prince. and Carey. F. G .. and ,I. V. Scharold. ,I. t:. Graves. 1990. Movements of blue shnrks (I'donace glauco ) in 2003. Use of poP-uII sntellite o~ h ival lags to de monst rotc depth nnd course. Mur. BioI. 106:329-342. 8u l'\'i"al of blue mnrlin (M(lHO im lIigricnl1l') released from Cn rey. F. G .. J . !\t. Teal. and J. W. Knnwi she l·. pelagic longlinc gear. Fi sh. Hull. 101(4 ): 939- 948. If)8!. The vi sceral temperntures of mackerel shnrks Klim ley. A. P.. S. C. I!euvers. T. H. Curtis. and S .J . Jorgensen. (LamnidaeJ. Physiol . Zool. 5oI !3 J: 334- 344. 2002. M ovement~ lind l! wimming behavior of th ree l! pe. Comp:lgno. L. J . V. ciel! ofsharks in La Jolla Canyon. California. Environ. 1984. Sharks orthe world : an a nnotated and illustrated BioI. Fishes 63:117- 135. catalogue of shark s pecies known to date. Part!. McCusker. J . E. Hcxanchiformes to Lamniformes. U.N. FAO s pecies 1987. The white shark. CarcharudOIl carc/'orlOs. has II synopsis 125. \'01. .1. pt. 1. 2-19 p. FAO. Rome. warm stomach. Copeia 198711 ): 195- 197. Cramer. J . NOAA (National Oceanogrnphic and Atmospheric 2000. S pecies reported caught in the U.S. commercial Administration). pelngic longtine nnd gill net fi s heries from 1996 to 1998. Atlantic coast chart 13003: Cape Sable to Cnpe 1998. NMFS S ustninnble Fisheries Di vi sion S~' D · Ballaras. National Ocean Service. Wa shington. D.C. 99/00-78:1-33. Sedberry. G .R .. and J . K. l.ocrer. Domeier. M. L. and H. Dewar. 2001. Satell ite telemetry of swordfish. X'plliu lf gla. 2003. Post-release mortality rate of striped ma rlin (ret· dillS. off of the eastern United Sutes. Mar. BioI. rolJtert/tI ouelux) caught with recreational tack Ie. Mnr. 139:355-360. FreshII'. Res .. 54(4): 435- 4·15. WhillOw. O. C.. I. F. G. liamllton. I). T. Matsuura. C. A. Ohatll. Dudley. S. F. J .. i\I. D. Anderson.Ueade. G. S. Thompson. and I ~ . M. Smith. and J . F. Allen . P. U. ~IcMullen . 1974 . Body temperature or three s pecies or whales. J . 2000. Concurrent scnvenging orr a whale carcnss by great Mammol. 55(3):653-656