Kiler Whale (Orcinus Orca)
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Thisrej)ort does nOt constitute a publication and is for information only. All data herein are o be considered provisional. Notice to Users of this Document
This document is being made available in .PDF format for the convenience of users; however, the accuracy and correctness of the document can only be certified as was presented in the original hard copy format. KIT 3' :RR WHAIE (orcinus orca) DEPREDM'ION ON I.DNGLINE CAromS
OF SABIEFISH (Anoc:J.qx:ma fimbria) m AlASKAN WATERS
Marilyn Elayne ~eim
National Marine Mammal I~hnratory Northwest arrl Alaska Fisheries Center National Marine Fisheries Service 7600 Sam Point Way NE, Bin C15700 Seattle, Washington 98115-0070
July 1988 ),
AffiTRAcr
Depredation by killer whales orcinus orca) on l~line catches of
sablefish (,Anop:J.occrna fi1nbria u..&l&(Llnly called blackcxxl, has been documented in the southeasten1 Berirg Sea am Prince William Soun:l areas.
Results of dockside inte1:views corxfucted in February am March 1988 with
ic Berirg Sea lon;;Jline fishennen suggest that predation ()(XUrS on 20%
. of the sets with an average IOOnetaIy loss of $2, 300 per day incurred durirg
the winter season Japanese lon;line vE?SSe1.s fishirg the Berirg Sea
between 1977 am 1985 reported whales interferrirg with ~tions on
~rox:imatel Y 15% of their trips. In Prince william Soun:l, a 25% predation
rate was reported based on inte1:views corducted with lon;;Jline fishennen
ar financial l as those which SU9:Jests s j 10; 1 osses reported for the Berirg Sea. Although interactions with killer whales am Alaskan lorgline ~tions have been documented as far back as the mid-1960' s, it is not possible to detemine if an increasirg tren:l in killer whale depredation is cxx;urrirg since reportirg has been inca'1sistent. various methcx:1s have been
tried to :reduce or eliminate whale depredation on u..&uu~iall y valuable
fish. Limited success has been achieved by 1) the use of dummy buoys, 2 ) lorg~ ncvements greater than 60 nautical miles, 3 'tt::1uIJu rary cessation of fishirg activities , 4) chan;irg the target species fran
blackcxxl to Pacific cod, am 5) the use of pot gear. '!he National Marine
Mammal ~hnratory will continue to collect information regardirg killer
whale fishery interactions in Alaska focussirg on the btpact on the
fishery, calculatirg the number of killer whale pods involved, am
developirg possible ways to reduce or eliminate whale depredation on l~line caught blackcxxl. iii CDNrENrS
Page
Intrcducti on Natural History Kill er Whales
Blackcxxl Fishery Jl1 Alaska
Killer Whale/Blackcxxl Fishery Interactions Prince William Soun:l Saltheastem Ber irg Sea isoJssion Acknowledgements References . .
LIST OF FIGURES
Page
Figure 1. 01n'111 ative Sightirgs of Killer Whales in Alaskan Waters
f1:an N:)AA' s Platfonrs of ~rb.mi ty P1. ogra:m (NMFS),
1958-86 .
Figure 2. location of Blackcxxl Fisheries in Alaskan Waters
Figure 3. B1ase-out of Pot Gear in Alaskan Blackcxxl Fishery
Figure 4. locations of Killer Whale/Blackcxxl Fishery Interactions
in Prince William Soun:l .
Figure 5 R1otcgraphs of Berirg Sea Blackcxxl D:unaged by Killer Whales .
Figure 6. Locations of Killer Whale/Blackcxxl Fishery Interactions
in the Sa.1tl1eastem Ber irg Sea
Figure 7. Smvey Positions of Japan - u. s. Joint Lorgline Research
in Alaska .
LIST OF ~RT~ Page
Table 1. Food Items of Northern Pacific OCean Killer Whales
Table 2. SUnunary of Methods En'ployed by Fishennen to Discourage
Whale Depredation on Lorgline Catches.
Table 3. Possible Methods to Help Reduce or Eliminate Killer Whale
Dep%edation on Lorgline Caught Blackcxxl. . ),
INmOWcrION
In A1.J;ust 19 8 5 , the N ti onal Marine Mammal T ~ hn to ry (NMML ) 1 earned 0
a fishery interaction involvirg killer whale orcinus orca) depredation on
lorgline catches of sable fish Anoc:J.qx:ma fiIOOria u,.a(~(.:)nly called blackcxxl, in Alaskan waters. Fishery interactions \tJere reported fran the southeastern Berirg Sea am Prince william Soun:l areas.
To assE'SS the nature am magnitude of the interactions in Prince
William Soun:l, the National Marine Fisheries Service (NMFS) Alaska Regional
Office contracted stlxties fcx::ussirg on dockside interviews with blackcod
fishennen. 'Ihese inte1:views \tJere con:lucted after the seasonal closure of
the 1985 fishery in Prince william Soun:l. Matkin (1986) reported blackcod
lon;;Jline losses of up to 25% of total catch, presumably due to killer whale depredation. A resident pod of killer whales (AB pod) was tentatively
identified as beirg the only pod involved, ani several members of this pod had holes or scars, which to be bullet 'WO.1nJs, in the dorsal fins
am elsewhere. '!he obserIation of these 'WO.1nJs ra ; concerns abo..tt i.rx:reased mrtality of killer whales fran fishery interactions. Fishery interactions with killer whales \tJere again reported durirg the 1986 blackcod season in Prince William Sam:i. In June 1986, NMML contracted further stlxties in Prince William Sam:i (Matkin et ale 1987a) to assess am evaluate the extent am types of interactions that \tJere c:x::currirg, ani to devel~ :r.~uUlt:lrlations to re::iuce them. Research obj ecti ves incl1 DEn 1) onboard sanplirg to determine damage to fish or gear am the anomt of osses in the catch direct1 y attributed to killer whale predation; 2) P1otograp1s to identify in:ti vidual killer whales pods involved in the interactions; am 3) an assessment of killer whale mrtal i ty CaxYwn; tantl y, Nl-HL began a :review of pertinent info:r:mation relative to the killer whalejblackccxi interactions in the Berirg Sea which inc11
A :review of U. S . cruise reports fran 1977 to 1985 u,.a(lJleted by
NMFS ' observers aboard Japanese u,.a(aue.rcial lorgline vessels in Alaska.
A :review of Japan-U. S. ive lorgline rcsrerch smvey reports f:ran 1978 to 1987; Interviews with fishennen, Japanese scientists, Alaska Deparbnent
of Fish an:i Game biologists, am marine mamnal biologists;
A :review of the history am tedmiques of the Alaskan lon;line fisherY.
P~carch by NMML continued into 1987 foo.1SSirg on issues in the Berirg
Sea which consisted primarily of gatherirg additional infonnation on the magnitude of the interactions am associated inpact on the fishery. con junction wi th the f ishirg i.rxiustry, smv ey f nrs am educa ti anal information TNere clistrib.rt:ed aIOOn;;J the fishennen in the blackccxi fleet.
Februazy 1988, tD!L initiated pilot field investigations in the sootheastern
Ber in;J Sea .
'!he pnpose of this :report is to summarize am integrate the available information on the killer whalejblackccxi lon;line i.riteractions in Alaskan waters. A brief introduction on the life history of killer whales blackccxi as ~l as a short description of the blackccxi fishery is provided. A preliminary assessment of the inpact of whales on the lorgline fishery is made am possible mitigatin;J measures are di~ NMURAL HIS'IORY OF IITT 3' WHAlES
Orcinus orca is a litan species, inhabiti.rg all major oceans arrl seas of the'tNOrld (Leatherwood arrl Dmlheim 1978). Killer whales primarily
CXD1r within 800 kIn of coastlines (Mitchell 1975), arrl in Alaska major concentrations CXD1r near larrl ~!:tSeS arrl aver continental shelf waters (Braham am ~eim 1982; Fig. 1).
Killer whales typically oc:x::ur in pods of fewer than 40 animals
Dmlheim 1981 ). Pod u..&(~ ti on to remain constant thra.lgh time with little intermix:in:J of in:tividuals aIOOrg pods (Bigg 1982). Orcinus a tq)-level carni. vore of the marine ecosystem with diets that vary :regionally. Alt:hcu3h killer whales primarily eat fish, they also consume other cetaceans, pinnipeds , arrl sea birds (nm1heim 1981; Table 1).
F~ j activities to be group coordinated with different strategies employed depen:1in;J upon the target prey. Blackcxxl has not been previously described as a prey item; however, this may be a reflection of cur limited knowlectJe of f~jn.;J habits of North Pacific killer whales since only a
!=aM I 111 of killer whale stanachs have been examined. In sane areas killer whales to be resident (occupyirg areas on a regular basis) while in other areas they to be transient or migratory occurrirg in areas on a basis only) (Bigg 1982). In IOOSt geogrcqi1ical areas,
IIDVements of killer whales to be :related to 1IXJVements in their food
SUR;)ly (Dmlheim 1981). With the exception of the inlarrl waters of Washi.rgta1 state arrl British Coluni:)ia (Bigg 1982), am Prince William
Souni, Alaska (Leatherwood et ale 1984), :reliable pc.p1lation est:i1nates are not available. ",...... ~.~ ...... ,.."....: ..::.\:'" ~.'\.,(. ,., ...""...... :. .'" .' . -:. ..,. .,. .. ~.( ~~ '/.....!~.j;,.~,?:-, . .;. .. ?-..\. '-..... ~ \ q ",-~,:. :::, .. . ~ ..--!;)'".-~ .;,('.' .~....- :- ~",", '"...", .;., ...y.. .::. .';...' ." . . ,, .-"~. '...... ,.., . ~ . ''
650 N
i. ~_ .( r ALASKA
St. Matthew I. Cook Inlet ~1 ; Kayak I. 600 ---:=;7 Nunivak I. .,r.-' '-:9.uN.' " ~..JI i' 4r;:~ r~/! . .r "1 . Gulf of Alaska BrittolBay ~v.ii!o7 - (r,; II ?- , .II "'1 . - ~Jo .....,JT : J to " 71: :f .Kodiak I. ::rlo 550 BERING SEA Jl au.a~ Cha;IOttl I 0' Q~" );r"","~ J. NORTH PACIFICOCEAN 500 1800 1750 1700 1650 1600 1550 1500 1450 1400 1350 1300
Figure 1. Cumulative Sightings of Killer Whales in Alaskan Waters from NOAA' s Platforms of Opportunity Program (NMFS), 1958- 86. ) ~),. ~; ~ ~), ), ), ), ), ) ,
Table 1. -Food of Northern Pacific Ocean killer whales (International Whal:iig ion 1982)
Arctic arrl SUb-Arctic
Walrus (O:lobenus :rosmaros ), bearded seal Erignathus barbatus ), rirged seal Bloca salm:m (Onoortlvnc:hus SR;). mrthern sea lion (~topi jubatus ), Alaskan fur seal Callorhinus ursinus), gray whale Fschrichtius robustus , bowhead whale Balaena InYSti-cetus), white whale leucas
Refererx::es: Scanm:m (1874); Cook (1926); Zenkcvich (1938); Nikulin (1982)(1941); Nishiwaki am Han:1a (1958); . Fay et ale (1979); Braham arrl Dahlheim
Northeast
California sea lion (Za:J.~us californianus el~ seal arxrost;..h~t.L~), Dall' s pozpoise (R1ocoenoides dalli), harbor po1:p:)ise Bloooena ahoooena), striped dolprin Stenella coentl~lM ), minke whal acutorostrata), blue whale 1I'IIlSCUl u,.a(wLll1 dolprin harbor seal Rloca vitulina), salm:m, Pacific hali1::ut (Hi~lossus hi~lossoides), carc:harhinid shark, ray .'1'OrcedQ califomica), greenlirg Hexagrammidae spp. ), lirg cod (~oqon elonqatus squid, Pacific IOOOnfish arrl deer (O:locoileus sp. References: Scheffer arrl SliR' (1948); Brown arrl Norris (1956); Nishiwaki arrl Han:1a (1958); Norris arrl PrescoLL (1961); Rice (1968); Barr arrl Barr (1972); Tarpy (1979); Balcarb et ale (1980).
Northwest
Cod (Gadus sp. ), flatfish, sardine, salIoon, tuna, mackerel, Atka mackeral, to , oepw. ), Dall' s ise , 00ni qxxis squid arrl octopJs po 1:p:) striped dol prin , Baird' s beaked whale (Berardius bairtlii goose-beaked whale cavll~b.-is), sei whale ~aenoctera borealis), pilot whale ~cepJal-9 ), finless porpoise (1:Jeqtlocaena ahocaenoiQes ), harbor seal
References: Nishiwaki arrl Han:1a (1958). BIACKCDD FISHERY AIASRA
Blackcod are widely distriOOtecl in the North Pacific Ocean an:l Berirg
Sea (Fig. 2) arrl are a u,.a(u.ercially inpJrtant grcunjfish resource for these regions (Sasaki 1985). Adult fish oc:DJpy continental slope waters arrl have also been foom on seannmts in the northeastern Pacific Ocean. '!he lower limit of bathymetric distribution is 2, 740 m (Beamish et ale 1979).
Juvenile fish are u,.a(m:)nly fourrl in surface waters arrl near the bottan
shallow nearshore waters of the northeastern Pacific Ocean, ~irg f1:an the
Gulf of Alaska to California Sasaki 1985). In the eastern Berirg Sea
1- an:i 2-year-old fish are rare; however, an e.xtensi ve distribution of
1- arrl 2-year-old age classes was observed f1:a:n unbnak Pass north to lat.
59ON. Cornmtrations of these yaJrg fish were centered in the 100 to 200 m depth zone arrl shallow water areas less than 100 m deep alorg the Alaskan Peninsula (Wakabayashi arrl Fujita 1981; Wakabayashi arrl Yabe 1981). since fish size increases with depth, it is assumed that juvenile fish neve into deeper waters arrl then rectuit to the adult stock. iff erences in maxiJ'II.nn size of fish arrl variations in color are reported for different geograprlcal areas .
'!he Japanese blackcod fishery was initiated in the northern Berirg Sea in 1958 arrl then stead;l y exparrled to other Berirg Sea areas arrl the northeast Pacific. U . s . observerS were placed aboard Japanese ~1.(-=t:'C ia1 lcn:Jline ve;se1.s beginnirg in 1977, to the Magnuson Fisheries
ConserJation arrl Management Act, to document the rnnnber of fish taken arrl the species u..a~i tion of the catch. u. S . interest in Alaskan blackcod
~eased durirg the late 1970' s arrl early 1980' s arrl by 1984 the blackcxxl fishery consisted primarily of u. s. ic vessel ... ~... .;-.... -......
650 N t ~ 600
Yakutat 2 '
Kodiak 54' 30 550 Berm,! Se;J
'00 . ~ .:;d;: ! Chirikof
Shumagin 500 Aleutian Islands
450
1 700 E 1800 1700 W 1600 1500 1400 1300 1200 1100
Figure 2. Location of Blackcod Fisheries in Alaskan Waters. Courtesy of: Fujioka et ale 1988. '!he blackcod fishery in Alaskan waters is still exparnj.rg. 'Ihree
types of vessel$ 0 ~lIlJrise , the directed fishery for blackcod: catcher boats, catcher/processors , arrl floatirg p~rs D.Je to limited space, the catcher boats typically have shorter trip durations an::l smaller rarges in which to used for ~te. Lorgline gear is na;t blackcod fishirg, accounti.n;J for 80% of the blackcod caught in 1987 while trawl gear accounts for 16%, arrl traps (pats, rect:an:;Jular arrl conical in design) account for 4%.
Disagreements abourxi f ishennen us irg 1 ine arrl pot gear as to which method is lOOre effective (e.g., quality of fish, species selectivity of gear, efficierx::y of fishirg, costs , etc. ). A of pot gear has recently been t:akirg place in the u. s. waters (Fig. 3). 'Ibis plan does not in::lude Prince William Soun:l (a state fisheries) or the Berirg Sea.
DJrirg l~line fishirg ~tions, a TNeighted g:t:'CJl1niline ~roximately
3 nautical miles (nmi) in lergth is deployed fran the fishirg vessel . An average of 17 skates usn~l ly 100-150 fathcm; in lergth) makes up this g:t:'CJl1niline. Depths of 200-550 fathans are usually fished for blackcod. nle annmt. of tine needed to set the g:t:'CJl1niline varies with weather arrl area corxti tions . Buoys arrl flagpoles, set at both erx1s of the g:t:'CJl1niline, identify gear arrl are essential to retrieval. Gargions ( averagirg 60 an in lergth) are set ~rox:imately 101 en apart with spacirg vcnyirg considerably vessels. circular hooks (#6 to #8), which have higher catch retention, have recently replaced the older staOOard "J" hooks. Each skate of gear has ~rox:imatel Y 200 hooks Typically the hooks are baited with herrirg or squid. Gargions are attached to the lon;;Jline by either halibut clips (metal clips) or beckets (YJOVen eces of line). Soak times 1410 W
600 N
Pot Gear No Pot to 12/31/86 Gear 550
, Pot Gear to 12/31/88 500 I WESTERN Pot CENTRAL EASTERN GearOK I 1700 W 1590 W 1470 W 1320 40'W
1700 W 1600 1500 1400 1300 1200
Figure 3. Phase-out of Pot Gear in Alaskan Blackcod Fishery. (gear on the bottan actively fishirg) vary by area ran;;Jirg fran 4 to 24 halrs. D:mIaqe to blackcod by "sam fleas" (small anpripods) can be severe with exterxied soak times in a:!rtain areas. Hydraulic winches aid in gear retrieval , with retrieval time varyirg considerably. Depen:linJ upon currents am bottan contours, grourxllines can becane tan3"led or snarled dur~ fishirg ~tions, thus significantly increasirg retrieval times.
KrUER WHAIE/BIACKCDD FISHERY INrERAcrI ONS
Prince william SaJn:l
'!he followin:J sunmary is principally based on contract reports suJ:mi.tted to NMML by Matkin (1986) arrl Matkin et ale (1987a). Killer whale depredation on l~line caught blackcod was first reported fran Prince
William SaJn:l durirg the 1985 fishirg ~50n Matkin (1986) estimated that
25% of the 1985 Prince William SaJn:l blackcxxl lon;;Jline catch was lost due to killer whale depredation. In 1986, iluu-=Uiately after the 1 April opening, blackcod fishennen once again reported killer whales t:akirg blackcod. Fishery interactions within Prince William SaJn:l were ocalized arrl only ocx:un:ed north of Knight Islam (Fig. 4).
Al thoogh I1\II1eI'OOS killer whales seasonally inhabit Prince William
SaJn:l, only one resident pXl was reported to be involved in the blackcod fishery interactions. 'Ibis group, previously labeled as AB pXl, consiste:i of 35 whales. Hall arrl Cornell (1986) documented that several members within AB pXl showed evidence of bullet wam:1s. In 1985 , three whales were reported m;~ fran AB pXli in 1986, three additional whales were absent arrl in 19 8 7 , another whal e was miss irg . Between 19 8 5 am 19 8 7 , a total 0 seven whales \tJere liste:i as missirg am presumed dead (Matkin 1988). )'- ... . ""
((f ALASKA ~c:~~s -4s.S-4G'c:-
.Jo.
~THI.
I;P SEAL I.
:fJ
,.LITTLE -t- ,z.. GREEN I.
, ..0 "'1..r '''1
,/"rhl N"dll
KILOMETERS
GULF ALASKA
14S"
Figure 4. Locations of Killer Whale/Blackcod Fishery Interactions in Prince William Sound. DJrirg killer whale depredation, blackcod are consumed when grcurrllines are beirg retrieved. Frequently, only blackcod heads or "lips" remain as evidence of orcinus predation (Fig. 5). Whole fish can show extensive rake marks made by killer whale teeth which can reduce their u..auu-=rcial value.
Catd1 per unit effort also declines in the presence of killer whales
(resul tirg in a greater number of ~(JIJty hooks). Occasionally, hooks were bent or straightened out. '!he conti tion of hooks, however, can not be cited as direct evidence of killer whale predation because hooks can becane snagged on the bottan durirg normal ~tions Initially (in 1985), the whales were observed nevirg into the area \tJhen the hydraulic winches \tJere ergaged to haul in the grcurrlline. Fishennen believed that hydraulic noise transmitted through the water attracted the whales. In 19 8 6 , whal es \tJere reported to position themselves by the b.1oys awarentl y wai tirg for lorgline retrieval ~tions to begin. DJrirg interactions, whales were one-fourth to one-half mile f1:an ~ting vessels, occasionally caning closer as the en:! of the grcurrlline ~:roached a boat. Depths of depredation are unknown; however, available data suggest that whales are not capable of f~; ~ fish when the lon;;J 1 ine is on the bottan
Numerous methods have been arployed by fishermen to either trick the whales or discourage them iran stealirg fish off the lorglines (Table 2).
In late Sl.ntmer of 1986, Nr+fi., received reports of fishirg crews usirg high- power explosives to frighten whales away fran their gear. Although fishennen believed that the explosive charges \tJere responsible for whales leavirg the area, confoun::ling events (such as an increase in nms of sal1ron) may have contributed to the whales' departure fran the area Source levels
arrl frequencies of the explosives used in Prince William Soun:l were .\ . !~~...-- - ' :':, . -.-" ", .. -., ' ~ .--- -:: , , - ~ ,...... :/"...
1iIIIIIrr'-
'tit
lji
i~:
Fi gure 5. Photographs of Ber; ng Sea Bl ackcod Damaged by Killer Whales. Courtesy of: Jim Stark. National Marine Fisheries Service, Seattle, Wa. ~, (~ =
Table 2. -SUnunary of methods enployed to ~ge whale depredation on lon;line catches Prince William Soun:i am ffi = Berirg Sea).
Methcxi Area Resul t Ccmnent
Seal banbs Not effective Occasionally a startled :response but whales did not leave area
Decoy boats Not effective Did not confuse whales. Blank sets ffi Not effective Whales i1mnediatel y returned to vessel with blackcod on lines .
, D.mmy buoys ffi Sane effect Whales occasionally lost interest, left area
Cal1b ined haul irg Not effective Whales nDVed between vessel stop ~tions Sane effect Occ.asionally helped.
Night fishirg ffi Not effective No difference.
Movements (short) ffi Not effective Movements ~ 60 rnni .
Movements (lon;;J) ffi Sane effect If IIKJVements greater than 60 rnni \tJere trade, vessels could sanetimes out :run whales. Q1ange of target species ffi Very effective SWitch to Pacific ccxi.
Shootm; Not effective Whales still in area Explosives Not adequately tested .
Elect. currents ffi Not effective No other infonnation.
Trap gear ffi Very effective No predation occurs Tan;le imi tator* Not effective Did not confuse whales. Acoust.i.c harassment device* Not adequately tested.
BarXJ pipe* Not effective No apparent difference.
* = Research testirg (blank sets arrl seal banbs included durirg teSt fishery). investigated an:! subsequent! Y describErl (Coastline Envirornnental SeJ:vices ,
Ltd. 1987). nJring fall of 1986 , the State of Alaska :ft.1rded stldies on
methods to ciiscc1Jrage whales f:rah depredatirg on lorgline caught blackcod in
Prince william Soon:i. Varioos methods were tried during this test fishery; however, none proved effective (Matkin et ale 1987b; Table 2) .
'!he 1987 status of fishery interactions involvirg killer whales in Prince william Soon:i is surmarized in Matkin 1988). '!he number of interactions am
associated whale D)rtality were reduced durin:J this season Whales \tJere not seen durirg the first \\1eek of the fishery. Scattered reports \tJere :received durin:J the secorxl \\1eek noting sane fishery interactions. By the third \\1eek
April, whale interactions were negligible. No aatitional reports were :received between April ani June. '!he fishery osed on 25 June 1987. In 1988, whale/fishery interactions in Prince william Soun:l were again documented. Attenpts to discan-age whales, usirg higp-power explosive
) 1 charges, \tJere not sucxessful (C. o. Matkin pers. commun
Sa.1theastem Ber irg Sea
Information pertainirg to killer whalejblackcod fishery interactions in the Berin:J Sea \tJere gathered fran a variety of sources. Longline fishennen reported blackcod depredation by killer whales fran Unimak Pass TNeSt to lorg. l72O 30'W. '!he number of encounters with whales \tJere reported to decrease just north of the Aleutian Islan:1s. However, when approach.irg. the waters south arrl \VeSt of the Pribilof Islan:1s , the number of killer whale interactions increased (Fig. 6).
C. o. Matkin. North Gulf Oceanic Society, p. o. Box 15244, Harer, Alaska 99603 . Pers. CarmJn, May 1988. , '
ALASKA 65O
CANADA
Bering Sea 600
550
1700 E 1800 1700 W 1600 1500 1400 1300
Figure 6. Locations of Killer Whale/Blackcod Fishery Interactions in the Southeastern Beri ng Sea. Whale behavior durirg fishery interactions in the Berirg Sea was
im;l ar to that described in Prince William Scmrl. When usin:J pot gear, whales \tJere not considered to be a problem. Berirg Sea fishennen stated that lower predation rates on blackccx:l by killer whales oocurl ed when their l~lines became snarled, despite the fact that fish \tJere still easily accessible. A targled or snarled groun:lline YJOlld not only present a large visual stinulus to a whale but it cculd also provide an active acoustical feature. As the line is retrieved, the variable tension on the line can cause snaR?irg or irg. Pert1aps whales avoid these targled sections of line because : 1) the line ret:XNery sourrls may elicit an avoidance response, 2) the Iilysical rearrargement of the lines may cause confusion, arrl 3) whatever cue the whales use to select specific fish species fran the line is interrupted or destroyed (e.g., the fish no lorger rocwe in the same way) . DJrirg fish detection, whales may rely on active echolocation, passive listenirg, or vision at close ran;Je). '!he erwironmental cues arrl sensory med1anisms used by whales to locate fish durirg fishery interactions are not knc:7Nn .
Reports \tJere available fran U. S . abse.tvers \tJOrkirg aboard 27 Japanese
~LILl.ercia1 lo~line vessels in Alaskan waters fran 1977 to 1985. ishirg OCCl1l:red fraIl the Canadian/Alaskan border (southeast Alaska), through the Gulf of Alaska, into the Aleutian Islams an:! southern Berirg Sea.
Information pertain:irg to fishery interactions involvirg killer whales was extracted arrl summar i zed.
Every vE?SSe1. within the Japanese fleet reported fishery interactions with killer whales, with all interactions confined to the Berirg Sea.
'!here were 56 reports available dc:x::umentinj depredation by killer whales on ). ),
l~line catd1es, representi.rg 15% of 365 trips. Depredation of blackcod
by whales occun:ed the year. since the consistency of
:teportirg is not similar ftan year to year, an increasirgjdecreasirg trenj of killer whale depredation on l~line blackcod cannot be determined.
In tion to blackcxxl, u. s. obse1:vers also reported killer wflales
t:aki.rg lorgline catches of greenlarrl turl:x:rt: (Reinhardtius hi~lossoides arrl arrowtooth floonier Atheresthes stanias Pacific cod Gadus
BaCt: ), grenadier Coryd1aeno~ acrolepis arrl rockfish
Sebastes SR'. ) \tJere never consumed. No information is available on the
behavior ani the J'1UI1i)er of whales involved in the interactions or the
cmcunt of fish taken. Japanese captains ani fishirg masters were \tJe1l
aware of killer wflales t:aki.rg blackcxxl (as \tJe1l as other grcun:1fish) in the Berirg Sea arrl ~d avoid areas where killer whales were reported. N\.nneraJs methods \tJere tried to d; ~ge the wilales (Table 2), rut on! lOOVements (greater than 60 in;J ~tions, ' lorg-rarge vessel runi), arrl chan;irg the target species to Pacific cxxi \tJere considered effective.
Begirmirg in 1978, un:ler a cooperative re5oarc::h agreement with Japan, NMFS scientists have participate::l in data collection activities aboard
Japanese lon;line roooarch vessels. Smveys begin in early May ani continue through A1.J;ust. Areas SUIVeyed incl\Xle the Aleutian IslanJs into the BerinJ Sea , Gul f 0 f Alaska, arrl waters 0 f sa.rt:heast Alaska ( Fig. 7).
Weather pemi t:tin;J , the vessel works a station per day, set:t.in;J out
~rox:imately 9 nmi of groon:iline generally beb.1een the 100 arrl 1, 000 m i.sdJa ths 65: N
600
550
500 Aleutian Islands
450
1700 E 1800 W 1700 W 1600 1500 1400 1300 1200 1100
Fi gure 7. Survey Pos i ti ons of Japan- U. S. Joi nt Longl i ne Research Alaska. Courtesy of: T. Sasaki. Far Seas Fisheries Research Laboratory, Shimi zu 424 Japan. Fishennen first reported interactions with killer whales in 1980 when
Japan expamed the lorgline research into the Berin;J Sea. Accounts of
killer whales depredatirg blackcxxi \tJere recorded each year fran 1980 through 1987 with the rn.nnber of encounters varyirg per year. Japanese
scientists stated that killer whales were known to interfere with lorgline
~tions in the Berirg Sea as far back as the 1960' s (T. Sasaki pers.
CCiuulL1I1 . ) 2 . In 1986 , 1987 , arrl 1988 NMML requested that specific data pertainirg to killer whales be collected durin;J research crt);~
include: location, date, rn.nnber of whales observed, any characteristic scars or deformities on whales (P'1otogra~ed when possible), am an assessment of the inpact on the fisheries. In 1987, a u. s. vessel participated for the first tbne in these lorgline research SlUVeys providirg additional information.
NMML also requested that personnel aboard NOAA vessels collect phot:ograp1s of Alaskan killer whales when possible. In 1986 , 191 phot:ograp1s were taken of Berin;J Sea killer whales. In 1987 , 594
~otograp1s were collected. NMML is continuirg P10t0graIDic efforts in
1988 as well. All ~otograp1s are sent to the Pacific Biological Station in Nanajn), British Columbia, canada, where CCI'l'parisons are made to phot:ograp1s of killer. whales taken throughout the North Pacific. Within- arrl between-year matches have been fCl.U'Xi in the Berirg Sea. Matches between Berirg Sea killer whales arrl whales fran other Alaskan areas have rot ocD1rred
T. Sasaki Far Fisheries Research T~hnratory, 7-1, 5-Qlane Orido, Shimizu 424 Japan. Pers. Cammm, 26 June 1986. In 1988, NMML initiated dockside inte1:views at D.Itch Hamor, Alaska
'!he blackcod lon;line fishery consisted of 12 vessels durirg this winter
season Between 8 arrl 22 February, six u,.a(.~ia1 lon:Jline fishemen \tJere
inte1:viE!f.t.1ed . In March, 'bYe additional dockside inte1:views u..&(ll-' leted.
Fishirg efforts (representirg a total of 147 days) had been concentrated
south of the Pribilof Islards arrl between AJa.rt:an Islarrl ani the Islards of
Four Mamtains. Fishennen set an average of 2. 4 lines per day with a mean
of 17. 5 skates per line. '!he rnnnber of hcxOO; per skate ranged fran 180 to
225 with a mean of 200, representirg an average of 3, 500 hooks per line.
Soak time typically rarged fran 4 to 24 hours, with 6 to 11 hours JOOSt
~IULJJ Trip duration depen:ied on vessel size arrl weather conti tions , rargirg fraIl 6 to 31, days. Seventy percent of the catdl was blackcxxl.
All of the fishennen who \tJere inte1:viewed (representirg 50% of the
winter lorgline fleet) reported that killer whales interfered with fishirg
~tions durirg the IOOnths of January, February, ani March.
Occasionally, 'bYe or three vessel separated by many miles s:im..11.tanea.Jsly reported whales depredatirg blackcod caught on lon;;Jlines. '!his SU9:Jests
that several pods \tJere involved. Pod size ranged fran 3 to 25 intividuals.
Fishennen believed that they could identify many of these whales based upon characteristic scars or dorsal fin shapes
Whales interacted with fishennen in 6 to 50% of the sets (mean =
2 0 ~) '!he 0 f IOOney lost per day by a s irg 1 e f ishirg vessel dur irg
the 1988 winter season based on the estimata:1 number of fish lost per set when killer whales \tJere present averaged, $2, 293 (with a low of $250 arrl a maxi.Jm.nn of $5, 000) . If the annmt of time lost either wai tirg for ~,
whales to leave or nevin;J the vE?SSe1. away f1:Qa the wi1ales is considered then the ~ted dollars lost per day ~d :i.n=rease.
J.b;t fishennen stated that shootirg, seal 1:x:IrtJs , arrl other techniques
were ineffective means of dri virg the whales away. Of particular interest
was the use of partial lorgline gear consistirg of dunmy buoys set in the
presence of killer whales. An anchor with an anple SlJR'1 y of line was
connected to a surface buoy. 'Ihree "dunmy J::uoys" \tJere set at 5- to 10- mile int:e.1:va1s in the general vicinity of the fishirg grounjs. When killer whales the actively fishirg lC?rgline was cut, an:! the vessel
hllJ-=Uiately went to retrieve the dunmy buoys. After retrieval of buoy number one, the vessel neved on to retrieve the secorn dummy buoy, arrl then onto the third. Oocasionally whales lost interest arrl Y1CUld leave the area. Whales have also been known to lose interest when ~tions shut- down for short pericx:1s of time (4 to 6 hours) but this method was not always effective.
Although not quantified, IOOSt fishennen believed that the rnnnber of interactions between whales arrl lorgline ~tions increased followirg the closure of the j oint venture trawl fishery. 1Jle concensus of inte1:views
incidents with killer whales in:ticated that \tJere increasin;J, arrl CCtun-=.rcial fishennen were becanirq increasirgly IOOre frustrated. All of the fishennen express€dthe need for :t"eScard'l into ways of alleviatirg these fishery interactions . Possible methcx:1s to help reduce or eliminate killer whale depredation of l~line-caught blackcod have been di~.JSSed several times aIOOn;;J ageocies arrl in:ti viduals involved in this particular issue ; the
ible methods are summarized in Table poss 3. Pi~ experimentation is needed to reveal the effectiveness of these various methcx:1s. Table 3. -Possible methods to help r~duc~~ or eliminate killer whale depredation on lOI'X1line caught blackcxxi.
Methcxi Ccmnent
Sparker devices Attached to garqion; emits flash of light arrl trans i ent soon::i to start! e whales.
Ft 1li:)er bullets Irritant to whales.
El ectr i cal an-rent Electrical shock to whales.
Maskirg 0 f soun:1s Interference of acoustical stlltulus responsible for attractirg whales to vessel
Playback sessions Recorded soun:1s fran lorgline ~tions reproduced into water. No food :reward associated with attraction to vessel soun:1s . B1hhle screen Interference with active/passive acoustical sense or vision of whales.
Accessory skiffs Deployed fran main vessel into vicinity of whales causirg possible visual ani acoustical harassment .
Sonic devices Acn1stic harrassment in frequency rarge that 'NCUld be sensitive to whales' hearirg. Li thitnn cloride/ ether St.rorg emetic prod11Cirg vani t~ reaction. Operant con:ti tionirg Behavioral nOOification of whales. Weak signal precedes strorg, aversive signal.
Management solutions a) Gear IOOdification; b) pot gear; c) seasonal restrictions (fishirg in an area when killer whale density may be low); d) actual fishery closure in areas with high levels of predation. lobl tiple/ CUl1'IJ1.ati varioos canbinations of above. DISaJSS ION
Killer whale depredation on lorgline-caught blackccd occurs t:hra1ghout a wide area in the southeastern Ber irg Sea Fig. 6). Most of these interactions occur close to lam or on the continental shelf break.
Prince William Sourrl, problems with killer whales \tJere IrOre l ized
(Fig. 4). When areas of interactions are cc:rrpn-ed to the whale distrihttion plot in Figure 1, it is clear that the blackccd fishery occurs in an area of high killer whale density.
Every Berirg Sea fisheDnan inte1:viaved had experienced interactions with killer whales durirg lorgline ~tions. Available information
that several pods of killer whales are involved in these interactions . Preliminary evidence iIrplies that similar pods are consistently :tesponsible for depredation activities on lorgline-caught blackccd in the Berirg Sea. Evidently, sane pods of whales just pass t:hra1gh the fishirg area arrl are not attracted to lorgline ~tions. Whale interactions are doc:1mv:mted durirg the winter fishery (January t:hra1gh March) as ~l as the sunmer/fall period (June t:hra1gh September) . A review of the available Japanese data inlicated that interactions occun:ed every nart:h of the year, suggestirg year-roun:l occurrence by killer whales.
Available data are not sufficient to assess whether or not an increas:irx1 tren:l in killer whalejblackccd fishery interactions is occurrirg in Alaska. Whale depredation on Berirg Sea blackcxxl caught on lorgline
gear occurs on 20% of the sets, based on calculations made durirg the 1988 winter 5'?a6OI1 'Ibis predation rate costs fishermen an average of $2, 300 per day in lost fish (which could vary significantly given differeooes in seasonal rates of predation). Rates of interactions may vary atOOl'q vessel with the ~ l ler catcher OOats (which are not capable of lorg~ rocwements) experiencirg IOOre p1:'OO1ems with whales . A vessel end ttirg a distinctive noise signature may also have higher predation rates if whales learn to associate specific SOl11'X1s with food.
Fishery interactions invol virg killer whales are not unique to Alaska.
Off Icelarrl, killer whales have been known to interfere with the herrirg fishery. In Not:Wegian waters, killer whales have been known to take halihIt off lorgline gear. In the North Atlantic, fishennen reported killer whales takirg tuna off their lorglines. Killer whales have also been reported to take tuna caught durirg l~line ~tions off Japan
(T. sasaki , footnote 2). Interactions between killer whales arrl lorgline tuna fishirg have been documented in the In:tian Ocean (IeathenJOOd et ale
1987). Off Tasmania, killer whales have been known to depredate trevalla
porosa ) caught in the chcp-line fishery (Tasmanian Fisheries
Developnent Authority 1981). An assessment of damage incurred was not given in the above accounts arrl it was not clear if there was a final resolution to the p1:'OO1em. Recently, spe.nn whale R1vseter maCl~ depredation of lon;;Jline-caught blackcxxi has been documented in the Gulf of
Alaska (reports to Nlef.fL fran NOAA personnel in 1986 , fishermen arrl biologists iran the danestic observer prcqram in 1988)
'Ihree rtant factors nust be p1.~ly evaluated when considerirg methcx:1s to reduce or eliminate marine mammal/fishery interactions: 1) the adverse effect on the mammals, 2) the adverse effect to the fishery, ani
3) the feasibility of the method beirg used in the fishery (gear, costs etc. ). Killer whale depredation behavior on lon;;Jline-caught blackcxxi is constantly beirq positively reinforced by food. Food :represents the
st.ron;Jest reward known for shapirg an anllna1' s behavior. To alleviate
these interactions wcW.d require a high level of effort or harassment ani
a l~-term ~lIud.tment to p:t~ly reshape, if possible, the present
behavior of killer whales. If several pods are involved, this wo..1ld
further u..&(lJlicate the effort.
Methods that are effective in reducirg or eliminatirg killer whale
depredation on lorgline-caught blackcod shoold continue to be used arrl
, expan:led up:m where arrl when possible. 'Ihese methcx:1s include: dunmy buoys, l~~ nevements 'tt::1up..Jrary cessation of fishirg ~tions,
chan;irg target species of directed fishery, arrl the use of pot gear. '!he
National Marine Manmal T ~ tw,ratory will continue to collect information
regardirg killer whale fishery interactions in Alaska focussirg on the
inpact on the fishery, number of killer whale pods involved, arrl possible ways to reduce or eliminate whale predation on l~line caught blackcod.
Special thanks are exterxied to personnel fran the Resource Assessment
arrl Conservation Ergineerirg arrl Resource Ecology arrl Fisheries Manage.ne1t
Divisions of the North\t,1est arrl Alaska Fisheries Center for provic1in;J access
to infonnation collected fran past research crt 1 ani their assistance in
the collection of lOOre recent data as well. In particular, I wish to thank
P. Dawson, s. ltk:Devitt, R~ Nelson, F. Shaw, J. stark, G. Stauffer, J. Wall,
arrl s. Personnel fran the National Marine Mammal T ~ ratory
assisted in the 1988 data collection. I thank J. Harvey, D . Bockus
S. de Blois, arrl B. Hanson. K. Peter, P. c;mn~Td arrl A. Merklein ~,
collected valuable info:cnation onboard blackccxi lon:Jline vessels as part of their participation in the North Pacific Fisheries Management Courx::il' s pilot date;ti obse1:.ver program G. Ellis (Pacific Biological Station,
British Columbia, Canada) provided expertise in :reviewirg all killer whale ~. tm' present knowledge arrl of the killer whalejblackccxi fishery interactions is due in large part to the ~tion of l~line iIxlustry, with particular thanks to R. Alverson
s OWners arrl I1\JIDerOJS 0 f ( F ishirg Vessel Associ at ion) meni:)ers the' f ishirg cx:mtI.D'li.ty. H. W. Braham, T. R. I.a1ghlin, N. Parks arrl the NMML Publication Review Ccmni ttee arrl Northwest arrl Alaska Fisheries Center Publications
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