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Transcription

1 OCSt.., "'1~2 Ecologc.1 Allocue. SY'tUsS 0' ~c. (( 1'B PnCfS OP MOSE Al) DsmuA1K2 a, Uc. ADLOft m.::da1'ons or lus SA P.-Pms fr LGL Muke rda Aaeoc:at_, nc 505 "-t ortbera Lllbta.1,"Sat. 201 ABdaonp, AlMke for u.s. tl_rala Sen.ce Al_1taa o.t.r CotlM11tal Shelf legon U.S. u.,c. of at.dor 603,,., EMt 36tla A.-... A8eb0ra, Aluke Coatraet _ CU LGL 'U r.-..ry 19"

2 OCS Study MMS StAllUS OWUOlMUc. 011'DB &BCf, Al) DS'ftJU8CB 011llAJoa WJLOU'r COC'DAra. OW101. SB&PDU&D by S.R. Johnson J.J. Burnsl C.. Malme2 R.A. Davs LGL Alaska Research Assocatel, nc. 505 West Northern Lghts Blv~., Sute 201 Anchorage, Alaska for u.s. Mnerals Management Servce Alaskan Outer Contnental Shelf Regon U.S. Dept. of nteror Room 603, 949 East 36th Avenue Anchorage, Alaska Contract no LGL Rep. No. TA February 1989 The opnonl, fndngs, conclusons, or recolmbendatons expressed n ths report are those of the authors and do not necessarly reflect the vews of the U.S. Dept. of the nteror. nor does menton of trade names or commercal products consttute endorsement or recommendaton for use by the Federal Government. 1 Lvng Resources nc., Farbanks, AK 2 BBN Systems and Technologes Corporaton, Cambrdge, MA

3 Table of Contents 'UU or cc»mll UBLBor cowmll AS'lAC'f... v nter-ste Populaton Senstvty ndex (PS) Norton Basn Plannng Area St. Matthew-Ball Plannng Area. North Aleutan Basn Plannng Area -,.... St. George Basn Plannng Area. v v v v.v M:1~~'lS.... LX 1lmlOll. 1 Background.. 1 Objectves Study Area Te1'1llnology Revew and SUllllUry0 f nfo1'1ll8t on on pnn ped Dsturbance nter-ste Populaton Senstvty ndex (PS1) Analyss of the Acoustc Envronment Populat ons DSULD 12. and Northern Fur Seal (Callorbnus ursnus L.) Background Patterna of Occupancy at Baulout Stes Locaton and Status of Northern Fur Seal Baulout Stes Prblof slands t. Pal lal l.,.tea.. se, Geor..tal Bogoslof sland Northe~n Sea Lon (Eumatopas -Background jubatus Schreber)... Patterns of Occupancy at Haulout Stes Locaton and Status of Northern Harbor Seal (Phoca vtulna L.) Sea Lon Haulout Stes Backgroun~ Patterns of Occupancy at Haulout Stes Locaton and Status of Harbor Seal Haulout Stes Walrus (Odobenus rosmarus (L.» Background Patterns of Occupancy at Haulout S~es Locaton and Status of Pacfc Walrus Haulout Stes Reactons of Pnnpeds to Dsturbance S :.2,,5

4 Table of Contents D8CU88O Nortbern Fur Seal Arborne Bo.e and Dsturbance "q 8oerce 8tatOllU'Y8oarc Underwater Nose and Dsturbance ~ 8oarc 8tat0ur7 8oerc.. Human Pre.ence and Dsturbance Nortbern Sea Lon Arborne Bose and Dsturbance oraa8oerce. tat0ur7 8ou'c.. Underwater Bo.e and D.turbance 1Dr. ao.rc.. Buman Presence and Dsturbance Harbor Seal Arborne Bos. and Dsturbance "q 8oerc 8tatoaar, 8oerc.. Underwater Nose and Dsturbance oraaoarc.. ltatoaar, 8oerc.. Human Presence and Dsturbance Walrus Arborne Bose and Dsturbance oraa8oarc.. Buman Pre.ence and Dsturbance Nortbern Fur Seal Nortbern Sea Lon Harbor Seal Pacfc Walru. Norton Ba.n Plannnl Area St. Mattbew-Ball 'Plannnl Area Nortb Aleutan Ba.n Plannng Area St. George Ba.n Plannng Area.DAmU C'DD ' APPDDCl8 89 APPDDU 1. ADL'f818 0., ACOUSTCDVllO'"'f 0., SLCTD PDmPD WJLOU!' S'DS 111DE AL&SU B.BG SU 90 ftodoc'ro 90

5 Table of Contents v DSULD AD DlSCU88OỊ Ambent Nose Characterstcs 91 ndustral Nose Source Characterstcs 94 Arcraft Nose Spectra 95 Small Craft and Commercal Vessel Nose Spectra 100 Transmsson Loss 103 Sound Transmsson n the Atmosphere 103 Underwater Sound Transmsson 104 Sound Propagaton Modelng 107 Ar-To-Water Transmsson 127 Comparson of Arborne and Underwater Arcraft Nose Spectra 133 COCLDoa LnDAmD CDD APPDU 2. DUCl.PrO AD AP 01' MalDU 1ft Sur. JWJLOUrSDS D 'rd BASDJ lqw SEA. 147 APPDU 3. DUCl.PrOU AD AP 01' ORlDU SEA. LU. WJLOU'rSTU m Tl AS-rBlQW SEA. 152 APPDU 4. DUC'PrOU AD AP 01' lmoa SU. WLOft SDS D TB BASDJ QTJG SEA APnDU 5. DSQFfOS AD AP 01',.cUC VAUD WLOft STU D 'rd BASDJ ptjg SEA. 207 APnDU 6. DDD m COUftS 01' OtLU SEA. LOU Ar 'l'dsd.ul WLOft srru D TB USDB lu. SEA APPDU 7. DftAD,p COUftS 01' uuoa SULS Ar 'l'dsd.ul WLOft srru D 'rd ASTBU QW SEA. 245 APnDU 8. DmDD COOS 01'.cUC tw.dsd Ar 'l'dsd.ul 1WLOft srru D 'rd US'DU Bl. SEA 257 APPDU 9. GLOSSA" ~ SCDrl'C n.- 1. Pnnped Termnology 2. ACOQltc Termnology

6 Lst of Fgures v LS1' or rguus Fgue 1 Hap of Berng Sea, Alaaka study area sbownl OCS plannng area General dstrbuton of.tbe northern fur a.al n tb. Bernl Sea, Alaska 3 Locatona of northern fur aeal haulout.tes n tb. Bernl Sea, Ala.ka 4 General d.trbuton of the nortbern sea lon n tbe Bernl Sea, Alaska... 5 Locatona of aportant baulout stea uaed by northern sea lons n tbe Bernl Sea, Ala.ka 6 General dstrbuton of the barbor seal n the Berng Sea, Alasu Varablty n count. of barbor.eals at two baulout stes n tbe ~ern. Sea, Alaaka 8 Locatons of aportant haulout ate. used by barbor aeal. n tbe Bernl Sea, Alaska 9 General d.trbuton of the Pacfc Walrus n the Berng Sea, Alaska. 10 Locatona ofaportant haulout stes used by Pacfc walruses n the Berng Sea, Alaska 11 Varablty n counts of Pacfc walruses at Cape Senavn, Ala'ska 12 Sumaary of baulout ste. n varous OCS Plannng Area. n tbe rnl Sea, Alaska LST or APPDDU rguus Fgure 1 Arborne ambent nose near beach areas 2 Shallow water ambent nose Small and medum arcraft nose spectra Helcopter radated nose spectra A. Small craft source level spectra. B. Medum vessel source level spectra

7 Lst of Fgures v Fgure 6 Beach geometry for sound transmsson near the shorelne FD Model calculaton of underwater from an offshore source to a recever Offshore transmsson loss Offshore transmsson loss Offshore transmsson loss Transmsson 10 near Unmak sland. depth. 70 m Geometry for ar to water sound trans.sson Factors for ar - shallow water sound trans.s.on Cessna 185 underwater nose spectra Arcraft nose spectra, underwater d~ta Maps of northern fur seal haulout stes on and on St. George and St. Paul.lands and Prblof alands BOloalof sland, Svutch n the Map. of mportant northern sea lon haulout ste. n the eastern Berng Sea Map. of mportant harbor seal haulout stes n the Berng Sea, Alaska Maps of mportant Pacfc walrus haulout ste. n the Bernl Sea, Alaska

8 Lst of Tables v LST or D'JlS Table 1 Summary of the tmng of arrval of haulng grounds and rookeres by northern fur seals of dfferent ages and sexes. St. Paul sland. Berng Sea. Alaska A summary of the occupancy of haulout stes on the Prblof llands. Berng Sea. Alaska. by dfferent age and sex classes of northern fur.eals... 3 Peak numbers of northern fur seals at major haulout stes n the Berng Sea. Alaska.. ~ 4 A suaaary of the occupancy of haulout stes on the Eastern Aleutan slands and 5E Berng Sea. Alaska. by dfferent age and sex classes of northern sea lons... 5 Peak counts of northern sea lons at major haulout stes n the Berng Sea. Alaska... 6 Peak counts of harbor seals at major haulout stes n the Berng Sea. Alaska... 7 Peak counts of Pacfc walruses at major terrestral 'haulout stes n the Berng Sea. Alaska nter-ste Populaton Senstvty ndex (PS) for northern fur sea haulout stes n the Berng Sea. Alaska nter-ste Populaton Senstvty ndex (PS) for northern sea lons haulout stes n the Berng Sea. Alaska nter-ste Populaton Senstvty ndex (PS) for harbor ~eal haulout stes n the Berng Sea. Alaska nter-ste Populaton Senstvty ndex (PS) for Pacfc valrus haulout stes n the Berng Sea. Alaska LST or APPDDU TA,u Appendx 1 1 Atmospherc attenuaton of representatve southern Berng Sea c~ddtods 2 Parameter values for FD.Beach model [as 110 L

9 Lst of Tables v Table Appendces 2 to 8 Descrptons of northern fur seal haulout stes n the eastern Berng Sea... Descrptons of northern sea eastern Berng Sea lon haulout stes n the Descrptons of harbor seal haulout stes n the eastern Berng Sea Descrptons of Pacfc walrus haulout stes n the eastern Berng Sea Selected counts of northern sea lons at the Walrus sland rookery (Prblof slands group), Selected counts of northern sea lons at Akutan sland (Cape Horgan rookery only), Selected counts of northern sea lons at Akutan sland (all stes, ncludng the Cape Morgan rookery), Selected counts of northern sea lons at the Sea Lon Rock rookery (Amak sland group), ~. Selected counts of northern sea lons at the Ogamak sland rookery (all stes), Selected counts of northern sea lons at the Bogoslof sland rookery, Reported counts of northern sea lons at haulout stes facnl the Berng Sea n the eastern Aleutan slands Reported counts of northern sea lons at haulout stes n the southertl Brstol Bay regon Reported COUtlts of northern sea lons at haulout stes n the northern Brstol Bay regon "Reported counts of northern sea lons at haulout stes (not rookeres) on the Prblof slands Reported counts of northern sea lons at haulout stes n the St. Matthew sland area Locatons of reported harbor seal haulout stes n the eastern Aleutan slands Harbor seal haulout stes, Unmak sland to Kvchak Bay Page

10 Lst of Tables x Table Harbor seal number. at the fve major haulout stes n the southern Brstol Bay area Harbor 8eal haulout ste., northern Br.tol Bay to Yukon Rver Harbor seal haulout.te. on the Prblof sland Reported counts of Pacfc walruses at haulout.tes n the southern Brstol Bay regon.... Pacfc walru. haulout ste., northern Br.tol.ay to Berng Strat ,.

11 Abstract x Ths study nvestgated the use of terrestral baulout stes n the eastern Berng Sea by four speces of pnnpeds, northern fur seal, northern sea lon, harbor seal and Pacfc walrus. Hstorcal nformaton on the use of each ste was summarzed. For a few stes tbere waa lttle or no nformaton about tbe number of anmals present and consstency of use of the ste, so we were unable to properly evaluate these. Avalable nformaton on tbe effects of arborne and waterborne nose, and buman dsturbance (fro. statonary and movng.ources) was revewed. We also conducted a detaled analyss of tbe acoustc envronment of eght haulout stes. These eght stes were represen~atve olothers used by each of tbe four speces studed. The analyses ncluded nvestgatons of (1) characterstcs of arborne and underwater ambent nose, (2) characterstcs of ndustral nose sources, ncludng arcraft, amall boats, fsbng trawlers and commercal cargo traffc, and (3) sound transmason loss n ar, water and tbrougb the ar-water surface. nter-ste Populaton Senstvty ndex (PS) As a means to evaluate tbe potental vulnerablty of each haulout ste to nose and dsturbance, we developed a quanttatve ratng system (PS) whereby an, ndex of senstvty was assgned to eacb ste. PS values were computed from rank scores assgned to egbt categores assocated wth each ste occuped by each of tbe four pnnped speces. The egbt categores were (1) tbe peak count of a partcular speces of pnnped ~ecorded at. ste snce 1980, (2) the mean maxmum number of anmals recorded at a ste durng tbe past three decades and durng the most recent count at tbe ste, (3) the proporton of tbe current total estmated Berng Sea populaton present at a partcular ste, (4) the age and sex composton, and the knds of behavoral actvtes that have been recorded at a ste, (5) the duraton of use. of a haulout ste, (6) consstency of use of a haulout ste, (7) varous physcal characterstcs of the ste, ncludng substrate type, local relef, water depth and proxmty to arports, shppng lanes, human settlements, and (8) speces characterstcs,.e. susceptblty of anmals of ths speces to

12 Abstract x nose and dsturbance and the potental for mortalty. Stes that rated hgh had hgh PSl scores and were consdered most senstve. Norton Basn Plannng Area There are 14 haulout ate. n tha plannng area; they are used by two of the four spece. of pnnpeds studed. No northern fur seals or-barbor seals haul out n sgnfcant numbers here. Twelve of the 14 stes are used by Pacfc walrus. Two haulout ~tes. the one on North Punuk sland. and the one on Kng sland ranked hlh n our PS evaluaton acheme. Northern sea lons have occasonally hauled out at Southwest Cape' on St. Lawrence sland and on nearby South Punuk sland. Bowever. there s no current nformaton concernng the use of these stes by.ea lons. St. Matthew-Ball Plannng Area n ths plannnl area 24 haulout stes are used by three of the four pnnpeds studed; there are no northern fwr seal haulout stes n ths area. Most of the stes (11) are used by northern sea lons, however none ranked hgh n the overall PS ev.luaton scheme. Pacfc walrus stes were second n abundance (8) and four of these. all on St. Matthew or Ball slands, ranked hgh. Barbor seal stes were least abundant (5) n ths plannng area, but the ste(s) n Kuskokwm Bay ranked relatvely hgh. Th. area. and the areas to the east near Avnof ~oat, may be the most northerly major harbor seal PUPpnl area. n the.a.tern Berng Sea. North Aleutan Basn Plannng Area Ths pl~ddng area CODtans 44 haulout stes used by three of the four speces studed; DO northern fur seals haul out n ths plannng area. Harbor seals used 22 of the stes ncludng 9 (20%) that rated hgh n our PS evaluaton scheme. Twelve stes were occuped by northern sea lons, and at least sx (14%) of these were ranked hgh. Ten stes are oc.cuped by Pacfc walrus, and fve (11%) of these were ranked very hgh.

13 Abstract x St. George Basn Plannng Area Ths plannng area has 54 haulout stes used by three speces; ths s the largest number of haulout stes n any of the four plannng areas n the eastern Berng Sea. There are no consstently used Pacfc walrus haulout stes, but all 22 northern fur seal haulout stes n the eastern Berng Sea are found here (Prblof slands and Bogoslof sland). Seventeen stes are occuped by northern sea lons, and 6 (11%) of these were ranked very hgh n our PS evaluaton scheme. At least 15 stes are used by harbor. seals. and three (6%) of these (two n the Foz slands and one on Otter sland) were ranked very hgh. Overall, we evaluated 120 of 136 terrestral haulout stes n four dfferent OCS Plannng Areas n the.eastern Bern, Sea. Of the 44 stes n.the North Aleutan Basn Plannng Area, almost half (20 stes; 45%) ranked hgh n our PS evaluaton scheme. Ths number represe~ts almost half of the total 41 moat hghly rated stes n the study area. Of the 54 stes n the St. George Basn Planan, Are., 19 (35%) were rated h,h; tbs number was strongly nfluenced by 10 hghly ranked northern fur seal stes on the Prblof slands. Of tbe 24 stes n the St. Matthew-Rall Planan, Area. 5 (21%) rated hgb a our PS evaluaton. and most (4 of 5; 80%) were stes occuped by Pacfc walrus. Of the 14 stes n the Norton Basn Planang Area. only 2 rated h,b n our PS evaluaton; both of these stes were occuped by Pacfc walrus.

14 Acknowledgements x fc:rwwnadc'h'm18 Many people belped u. complete tbs.tudy. n partcular, we thank the b,ologsts, and resource and nformaton specalst. wth state and federal agences n Ala.ka, Wasbngton State, and Canada. Tho.e at the Natonal Harne Mammal Laboratory (NMKL). Ratonal Harne Fshere. Servce (MPS), Seattle, who helped are Bud Antonell., Chuck Fowler, Roger Gentry, Bro lajmura, Tom Loughln, Rck Herrck and Ann Yorke. We especally tbank Sherry Pearson, nformaton specal.t at tbe NMHL lbrary f~r auownl us ~ree access to fles and publcaton Bro tajmura lave u. updated up. of nortbern fur seal rookeres and baulout.tes on tbe Prblof sland Peter.Boveng, NHFS Southwest Fsbere. Center. Ja Jolla, provded recent report. on tbe status of the harbor seal and fur seal Tho.e wtb tbe Ala.ka Department of Fsb and Game (ADFG) wbo belped are Glen Seaun n Ancborage, Katby Frost. Lloyd Lowry, and Cbrs Smth n Farbanks, Ken Taylor n Dllngham, and Dck Sellers n Kng Salmon. Tbe follownl people at tbe U. S. Fsb and Wldlfe Servce (USFWS) also helped: Scott Scblebe n Ancborage, Sue Blls n Farbank., Dave Fsher n Dllngham, Randall Wlke n Kng Salmon, Chrs Dau n Cold Bay. and Art Sowls and Tom Early n Bomer. Hke Bgg. wtb the Department of Fshere. and Oceans (DFO). Nanamo, Brtsh Columba, provded acce to tbe extensve reprnt collecton at the Pacfc Bololcal Staton. nformaton specalst Gordon Hller also helped fnd mportant paper. and reports at the DFO lbrary n Nanamo. Varous people at LGL also helped durng ths study. Dale Herter (LGL Alaska. Anchorage). Dave Roseneau (LGL Alaska. Farbanks), Bll Kosk and John Rchardson (LGL Lmted, Kng Cty) and Kerry Fnley (formerly LGL Lmted, Sdney. B.C.) provded relevant lterature and nformaton concernng the effects of nose and dsturbance on pnnpeds. We also thank Greg Green, Envrosphere Co., Bellevue. Washngton, who gave us unpublshed nformaton on sea lons.

15 Acknowledgements xv Steve Treacy, Mnerals Management Servce OfMS), Anchorage, Alaska, helped set the geographcal lmts to the study area, and arranged for us to get offcal protracton dagrams of the coast and slands of the eastern Berng Sea. We thank Steve for hs patence and cooperaton throughout ths study.

16 ,

17 ntroducton 1 Background n Alaska four speces of pnnpeds congregate. often by the thousands or tens of thousands. at specfc terrestral haulout stes along sland and manland coasts of the eastern Berng Sea. These speces are the northern fur seal (Callorhnus ursnus). northern or Steller sea lon (Eumatopas jubatus), harbor seal (~vtulna rchards) and Pacfc walru. (Odobenus rosmarus dvergens). Except for the walrus. these speces may occupy terrestral haulout stes durng puppng. nursng. matng and lloltng.whch are all potentally tmes of elevated stress. (Matng. puppng and nursng by Pacfc walruses occurs durng January through June n the pack-ce rather than at terrestral stes.) Consequently. acoustc andor vsual dsturbance of anmals at terrestral haulout stes could adversely affect these and other functons. or could further decrease resstance to parastc nfecton, thermoregulatory mparment. dsea.e and other stre.s factors. n recent years, the northern fur seal. northern sea lon and harbor seal populatons n the North Pacfc regon ncludng Berng Sea have experenced sgnfcant declnes. These declnes have been attrbuted to a varety of causes. e.g entanglement n abandoned or dscarded fshng gear. dsease and parastc nfectons. and reducton. (prncpally through overfshng) n the abundance of prncpal prey speces. However. there have been few studes of the potental senatvty of these pnnped speces to ndustral dsturbance near haulou~ st Addtonally. although the Berng Sea populaton of the Pacfc walrus hal ncreased markedly n the past decad.s. mass mortalty has occurred at 10 locatons. and t has been suggested that.ths speces may be senstve to certan vessel and arcraft traffc. Lterature exsts whch dentfes Berng Sea haulout locatons for the four pnnped speces. However, ste-specfc populaton nformaton has not been combned wth known behavoral and acoustc nformaton to descrbe the potental for dsturbance of these four pnnped speces by ol and gas development actvtes n the Berng Sea. The present study was conducted on behalf of the U. S. Department of nteror, Mnerals Management Servce, n

18 ntroducton 2 antcpaton of eventual ol and gas exploraton and development on the Outer' Contnental Shelf of the eastern Berng Sea. The purpose of ths study was to provde an up-to-date and comprehensve synthess of avalable nformaton of the known and expected effects of (1) underwater nose, (2) nearby vessel traffc, (3) low-flyng arcraft and (4) other assocated human dsturbances on major concentratons of northern fur seals, northern sea lons, harbor seals and walruses at rookeres and haulouts n the eastern Be~Ag Sea. Objectves The prncpal objectves of ths nvestgaton. were as follows: 1. SU1lllll8rzethe lterature and compare the year-round utlzaton of major Berng Sea haulout stes by northern fur seals, northern sea lons, harbor seals and Pacfc walruses. Ths objectve.ncluded (a) a revew of avalable lterature on the dstrbuton of the four pnnped.pedes n the Berng Sea adjacent to Alaska, (b) the dentfcaton of the major haulout stes for these speces, (dan analyss of the use of major haulout stes by dfferent age and sex cohorts, and Cd) a sullllllarzaton and estmaton of the year-round use and relatve bologcal value of each major haulol,lt ste to each speces. 2. Summarze and quantfy avalable nformaton on the effects of ndustral dsturbances on the four major speces beng studed. ths objectve ncluded Ca) a summary and comparson of avalable nformaton on the lllllledate and long-tenll effects of acoustc and vsual dsturbance on ndvduals and on concentratons (haulout stes) of the four speces of pnnpeds, (b ) a dscusson of the applcablty of nformaton avalable for other pnnped speces, and (e ) a revew of responses of marne madlllals to varous acoustc stmul. 3. Based on data obtaned n land 2 above, estmate the relatve vulnerablty of the major haulout stes to ndustral dsturbances. 4. Assess whether dsturbance to specfc haulouts may have populaton-level effects on the above mentoned four speces. 5. Conduct an analyss of the acoustc envronment of representatve pnnped haulout stes.

19 Methods 3 Study Area. 'l'hestudy area for ths project s the Berng Sea adjacent to Alaska (Fg. 1) ncludng the manland coast from Cape Prnce of Wales n the north to Cape Krentzn at the tp of the Alaska Pennsula, n the south. t also ncludes all of the slands n the Berng Sea from Lttle Domede sland n the north (n Berng Strat) to Unmak sland and the Fox slands n the eastern Aleutan chan. Umnak sland s the most westerly sland consdered n detal n ths revew. Some nformaton from haulout stes on the Pacfc Ocean sdes of some of the Fox slands (.e., Ugamak., Aktak.) are also consdered. n general, however, we have restrcted our nvestgatons to haulout stes on the Berng Sea 'des of the eastern Aleutan slands.

20 Methods 4 U.S.S.R. leoo..' ST. MATTHEW. HALL ALASKA HALL.. ". '. 100m.. 6()0 ~ST. 6'... : MATTHEW.' ST. GEDfK;E BASN ",. NORTH ALEUTAN BASN.., "" !.l:) 2flO..., 3boKm 0 ~ fX)'".. ''', ~0 PACFC OCEAN p Fgure 1. Map of Berng Sea, Alaska study area showng oes plannng areas. &

21 Metbods 5 Termnololl Throughout tbs report we use.tbe term. 'baulout ste', 'rookery', and 'baulng ground' or 'baulout'. These terms refer to any lte wbere pnnpeds tradtonally haul themselves out of the water; however, tbe terms are not uled ynonymously. Haulout stes are composed of 'rookeres' and 'haulng ground.' (or 'haulouta'), whch serve dfferent bologcal functons for northern fur leall, nortbern sea lon., and other eared seals. For northern fur seals, rookeres are areas generally near the water where females have ther pup., where males and female. congregate to breed, and where pups are rased. Haulng ground. are generally located near.the rookeres but are more nland, and are occuped by non-breedng ndvduals durng the breedng season. Some adult male. may move to haulng grounds after tbe breedng sea. on. Smlar to northern fur seals, northern.ea lons gve brth, nurture ther pup., and breed at tradtonal, well e.tablshed rookeres. Haulng grounds are often adjacent to the rookeres and are occuped by non-breedng or "bachelor" male. (3+ years of age), and later by harem bulls. Bachelor bull northern sea lon. aggregate at haulng ground. and spend much of ther tme mock-fghtng or makng occasonal trps nto the rookeres wbere tbey are chased by reldent male.. Unlke fur seals, northern sea lons haul out throughout the year, rather than only durng the breedng season. n the present report w ke a dstncton between northern sea lon rookeres (breedngpuppng area.) and haulouts. Harbor seal. often congregate to feed and gve brth at tradtonal ste., but tbese ste. do not ft tbe defnton of a rookery as descrbed above,.e., where males bave well establshed terrtores n whch females are defended and bred, and pups are born.

22 Methods 6 Walrus (.anly malel n the prelent study) haul out at tradtonal terrestral stel n the study area, but these stes are not rookeres; few females are present at terrestral ltes n the Berng Sea except n the far north durng late fall. Durng thl perod, males may fght over females, but vrtually all breednl and puppng occurs n the pack-ce durng late wnter through sprng. The 'Glossary' provded n Appendx 9 lves more detals and documentaton of termnology used n ths report. levew and Summary of nformaton on PnQped Populatonl and Dsturbance ntally we conducted a learch of data bases such as ASFA (Aquatc Scences and Faher.s Abstracts), ASTS (Arctc Scence and Technology nformaton Servce), BOSS Prevews (Bologcal Abltractl) and NTS (Natonal Techncal nfot'1uton Servce). We also conducted thorough searches for relevant nformaton n lbrarel at (1).the U: S. Natonal Marne Mammal Laboratory (Nat. Mar. Fsh. Serv., NOAA, Seattle, WA), (2) the Pacfc Bologcal Staton (Dept. Fsh. and Oceanl, Nanamo, B.C.), (3) the Unversty of Brtsh Coluaba, Vancouver, B.C., (4) the varoul offces of LGL Lmted (tng Cty, Ontaro; Sdney, B.C.) and LGL Aluka lesearch Assocates (Anchorage and Farbankl, Alaska), (5) offce and taff lbrares of the U. S. Fsh and Wldlfe Servce n' Alaska (Anchorage, Farbanks, Kng Salmon. Cold Bay, Dllngham) and (6) offce and staff lbrares of the Alaska Dept. of Fsh and Game (ADchoral~, Farbanks, Kng Salmon, Dllngham, Nome). mportant sources of ';aluable nfor.a ton for thl tudy have been. personal communcatons froa people who are currently workng or have n the pas t worked extensvely wth pnnpeds n the Berng Sea and elsewhere. We su1l8rzed pnnped populaton nformaton for each major haulout ste,.e. wth a few exceptons, a ste where at least 1% of the total populaton had been recorded snce Snce populatons of some speces have fluctuated greatly n the past 2-3 decades. and no doubt wll contnue to do so n future years, we decded that t was not justfable to exclude a haul out ste because- t had not been used n the past 10 years.

23 Methods 7 Counts at haulout stes may be nf~uenced by a large number of factors, e.g., tme of year, tme of day, weather condtons, vablty, type of observaton platform (arcraft, shp, boat, land), count procedure, observer ablty, dsturbance levels at stes, and nature of survey (opportunstc or otherwse). Counts at some stes on the same day may fluctuate from several thousands (or tens of thousands) of ndvduals to vrtually none. As noted n DOst suldld8rytables n ths report, counts of northern sea lons, harbor seals and Pacfc walruses are from many dfferent sources, and many data have not been collected n a systematc or consstent manner (data for the northern fur seal are an excepton). For ths reason, n our man summary tables we present peak counts at each ste for each of the four decades snce the 1950's (Frost et ale 1983 used a smlar approach), as well as the most current count and year of most current count for each ste; detals of all other ndvdual counts are gven n Appendces 6 through 8. n many cases, the most c~rrent count s often sgnfcantly lower than the peak count for the 1980's (because of recent regonal populaton declnes). Wb~n avalable, we gve a breakdown by age and sex. nter-ste Populaton Senstvty ndex (PS) The mportance and vulnerablty to dsturbance,.e. the senstvty of each haulout ste used by each of the four speces, was computed and an nterste Populaton Senstvty ndex (PS) was generated for each ste usng a seres of varables or factors related to (1) the locaton and major physcal characterstcs of the haulout ste benl consdered, (2) the status, composton and trend n number. of the populaton benl consdered, and () the spece. benl consdered and ts general response to dsturbance (based on the lterature). These varable factors and the way the1 ft nto the nterste Populaton Senstvty ndex (PS) are de.crbed n more detal below. The eght varables assocated wth each speces and each ste were ranked on an nteger scale (l through n) accordng to the tota1 numbsr of ste. (n) consdered for the speces n queston. Where varables (or factors) at two or more stes were of equal mportance, they were treated as tes (ranked equally). n nstances where two factors were hghly nterdependent, they were pooled nto a sngle complex factor n order to reduce bas, t

24 Methods 8 should be ponted-out, however, that most of the varables consdered n ths analyss were to lome degree dependent on one or more of the other varables; t was not possble to elllnate all redundancy andor bas n ths rankng procedure. Thu, becaule of nherent unavodable bases, the evaluaton procedures that we used hould not be consdered a rgorous statstcal treatment. A mean rank was computed from the rank scores for each ste. These means were then ranked agan to determne the overall nter-ste Populaton Senstvty ndex (PS) for each ste consdered. Par e"lple, f there were 25 haulout ltel descrbed for a partcular lpecel of pnnped, then the ste wth the lowest overall an rank (based on currently ava~able nformaton) had the hghest PS score--.e., was consdered a lte where severe dsturbance could caule populaton-level effects. follows: mportant varablel or factors consdered n evaluatng ea~h ste were as 1. The peak count of a partcular speces of pnnped recorded at a ste snce Ths peak emphalzes the most current count (1980's count and the molt current count) at a partcular ste. Peak count data for northern fur leal, northern sea lon, harbor seal and Pacfc walrus a~e from Tables 3, 5, 6 and 7, respectvely. 2. The mean maxaum number of anmals recorded at a ste durng the past three decades and durng the mos t recent count at the ste. Th s provdes an ndcaton (but only an ndcaton) of the degree of use of the' ste over the past 30 years. The values gven n Tables 8 through 11 are based on the average of peak counts for each of the 1960'1, 1970'1, 1980'1, and the most current count at the stes gven n Tablel 3, 5, 6 and 7. Data from the 1950's, although presented n many of the revew tables n order to provde hstorcal perspectve, have not been ncluded n the evaluaton scheme. 3. The -proporton of the current total estmated Berng Sea populaton present at a partcular ste. A ste that supports a large percentage of the populaton s consdered more mportant than a ste that supports only a small percentage. The values gven n Tables 8 through 11 are the proportons based on current counts,.e., the most current count recorded snce 1980 and the most recent poj)ulaton estmate gven n Tables 3, 5, 6 and 7, respectvely.

25 Method Age and sex compolton, and the knds and amount of behavoral actvtes that have been recorded at a.te. A large and complex ste that. u.ed for puppng and nur.ng, and for breedng was con.dered to be more mportant to a.pece. and potentally more sen.tve than a.mall ste or a ste u.ed only for restng, or only by subadults. Ths factor therefore actually ncludes several mportant varables-- (1) age.ex compolton and complexty of the ste, and (2) behavor-- and both are hghly nterdependent. nfor.aton on the agel sex composton (and thus behavor), and complexty (number of subdvsons and areal extent) of the.te are gven n Tables 3, 5, 6 and 7, and n Fgurel 13, 14, l' and 16, respectvely.,. Duraton of u.e of a haulout.te. A ste that s u.ed for a large part of the year s conadered to be aore mportant and more vulnerable than a ste used only ntermttently (e.g., only durng mgraton). Snce ates that are u.ed for a large part' of the year often are the rookerea, where varous age. and sex cla es and a varety of dfferent behavors are exhbted, ths varable s obvoualy related to aeveral of the other varable.. Duraton of use was computed for each.pece. uang nformaton gven n the lterature; e.g., Table 2 for northern- fur seal where vrtually.. all stes have rookeres and are occuped for about seven months (0.583 yr). Only.01M northern.ea lon.te. are rookerea or are near rookerea, whch are occuped for an extenave perod (0.500 yr, Table 3). Other aouthern Berng Sea atea may be used for about yr and more northerly.tea are u.ed for only yr (.ee Table 9). Harbor seal stea are also occuped for varous duratons dependng on ther geolraphc locaton and the average polton of the ce front durng wnter. Southern ste. are occuped by seals all year whle the northerly stes are occuped for only about sx months (0.500 yr, Table 10). Smlarly, Pacfc walrus occupy stes for varous perods dependng on the sex and age composton of the anmals and the locaton of the ste (Table 11). Soutbern stes are used almost exclusvely by males for perods rangng fra- 2 to 7 months (0.167 to yr). Northerly stes may be uaed by all ag88 and sexes for perods rangng from 2 to 4 montha (0.167 to yr). 6. Cona.t.ncy of u.e of a haulout ste. A.te that s u.ed every year. consdered to be more mportant and more vulnerable than a s t e that a u.ed only.poradcally. Rookeres are used mo.t consstently fro. one year to the next; thu, there s a strodg relatonshp between con.stency of u.e of a ste and the agesex classes, behavors and duraton of use of a ste. Conastency of use of a sce.s -determned by the frequency wth whch anmals are recorded at stes durng dfferent survey. over a perod of years. 7. Ste characterstcs, Le., the physography and assocated susceptblty of the ste to dsturbance. Ths factor s based on the major physcal characterstcs of the ste,. e.g., the substrate, vertcal relef, bathymetry, etc., n the llllledate vcn ty 0 f the ste, and ts proxmty to sources of dsturbance. Any ste located wthn 5 km of a source of nose or dsturbance (shppng lanes, arports andor ar traffc lanes, settlements, etc.) was ranked hlgh

26 Methods 10 n our evaluaton scheme. Other stes not located close to nose or dsturbance sources were ranked n accordance wth the physcal characterstcs of the ste. 8. Speces characterstcs, Le., susceptblty of a speces to dsturbance. Ths factor s based on how the speces responds to ds turbances of dfferent types (baaed largely on the lterature presented n ths report). t s dependent to a degree on the compo.ton (ale.ex, -behavor) of the anmals pres.n~ at the ste. how that seamant of the populaton s affected by dsturbances, and Whether. or not there s a hgh, medum or low probablty of mortalty as a drect or ndrect result of nosedsturbance. Speces that are known to have suffered mortalty as a result of Dosedsturbance (e.g., Pacfc walrus, northern sea lon, harbor".eal) were ranked hah, and others (e.g., northern fur.eal) were ranked lower (Tables 8 through 11). Analyss of the Acoustc Envronment We also conducted a separate analyss of the acoustc envronment of eght haulout stes (see Appendx 1). These stes were consdered to be representatve of those used by each of tbe four pnnped speces consdered n tbe present study. The pbyscal condtons (locaton n tbe study area. proxmty to nose sources, ste substrate, slope of beach and sea bottom, bottom type), and pnnped use of these egbt stes were ncluded n our selecton crtera. The analyses ncluded nvestlatons of the followng topcs: 1. Cbaracterstcs of arborne and underwater ambent nose. 2. Cbaracterstcs of ndustral nose sources, ncludng arcraft, small boacs, fsbnl trawlers and commercal cargo traffc. 3. Sound transmsson loss n ar. water and tbroulh the ar-water surface. The ambent nose characterstcs of the stes were estmated usng data obtaned from studes of smlar areas. The nose source characterstcs were obtaned fro~ data reported n the lterature and data n the archves of BBN Systems and Technologes Corporaton_ Transmsson loss 'characterstcs for arborne and underwater sound were estmated usng standard analytcal procedures and computer models (see Appendx 1). An analytcal procedure was developed for predcton of transmsson of sound from arcraft nto shallow

27 Methods 11 water, snce an ex.tns procedure was not avalable. Procedures are descrbed for usns the nfonaaton obtaned n ths study to predct nose exposure levels and to develop 'zone-of-nfluence' e.tmates for the varous speces of concern. All of these procedurea are de.crbed and dscussed n detal n Appendx 1.

28 Results 12 USULU wth The followng results are presented n sev~ral sectons, n accordance the general objectves of the study. The frst sectons gve descrptons of mportant backaround lfe-hatory nformaton about each of the four speces, nfonaaton about patterns of occupancy and hnory of use of key haulout stes~ and nformaton about the locaton and status of haulout stes for each of the four speces n the eastern Berna Sea. Later.ectons (1) revew nformaton on the effects of dsturbance and no.e on pnnpeds, and (2) revew nforuton on acoustc proce es that y be relevant to OCS development near pnnped haulout stes n the eastern Berng Sea (Appendx 1). Specfc descrptons of the physcal characterstcs and maps of each major haulout ste are gven n Appendces 2 through 5. Northern Fur Seal (Callorhnus ursnus L.) Background The northern fur seal belongs to the famly of eared seals (Otardae); t s a medum-szed pnn~ed wth adult bulls n prme condton on ther br~edng terrtores measurng about 2-3 m n length and weghng between 135 and 280 kg. Northern fur seals reman at sea for moat of the year, often far from shore along the contnental shelf and slope. The dstrbuton of northern fur seals n the Pacfc s from the Berng Sea to Southern Calforna and Japan (Fowler 1985, n press). Fgure 2 shows the general dstrbuton of ths speces n the ea. tern Berng Sea. No ndvdual fur seal older than a neonate spends longer than days of the year on shore (Gentry 1981). Hales reach sexual maturty by about 6 years of age and female. by 4-5 years of age; they gve brth to a sngle pup (very rarely twns) weghng kg each year. Adults may lve to be almost 25 years of age (Fowler 1985, n press). Northern fur seals are the most abundant marne mammal n the Berng Sea, but recent declnes have occurred throughout ts range. The current worldwde populaton of 1,173,000 s sgnfcantly less than the 1,765,000 ndvduals

29 Results 13 6~.:'tERNG.' SEA.. ~. OOm.. ; ~ '. '..... '".,.. '- '. '.... :.' :~.-.:) ; :... "f~ :'" :~.... :,'.e ""....., ALASKA... -.'. NORTHERN FUR SEAl. mseaeonal Dmbutlon, (May-November) [[] Yecr-Rowld Dstrbuton' 00 -, ". Mcjor FcraQng MQftllon ;.' Corrdor, 5"'0,.,:.: ~m..j.'.... ~"'..., ' "!... _ o f:).~ _ "..:.:.::.:.:::.:; m-.. ( 0 PACFC OCEAN J.:.._----o. 200.:.J1'- 6..dO JbJ Km Fgure 2. General dstrbuton of the northern fur seal n the Berng Sea, Alaska.

30 Results 14 reported n the md 1970's by Lander and Kajmura (1982). Smlarly, the number of fur seall estmated on the Prblof slands has declned from 1.3 mllon n the md-1970's (Lander and Kajmura 1982), to 0.9 mllon n the md-1980's (Nortb Pacfc Fur Seal COllllllsson 1984, cted n Bgg 1986:383), to the current estmate of about 0.8 mllon ndvduals. Ths represents a declne snce tbe md- to late 1970'1 of about 4-8% per year (average 6.1%; Fowler 1985). Recent studes ndcate that the declne may ll part be the result of ncreased mortalty of younger age classes tbroulh entanllement n abandoned and lost fsbng gear and other debrl (Fowler 1984, 1985, 1987, n press; YOlhda and Baba 1985). Becaule of tbe declne, the ladonal Marne FSheres Servce recently (May 1988) lsted the Prblof.lands populaton of northern fur.eals a. a 'depleted peces'. under. teras of the'marne Mammal Protecton Act of 1972 (MMPA). Fur seall come ashore at leveral mportant locatonl n the North Pacfc, Berng Sea and Sea of Okhotsk, though ma'nly durnl and after the breedng.eason (May-ovember). The dltrbuton of northern fur leal haulout stes (rookefel and haulng groundl) n tbe eastern Bernl Sea s lmted to the Prblof sland. ncludng Svutch (also known a. Sea Lon Rock) and Bog08lof lland (Fg. 3 and Appendx 2) whch are used by about 70-74% of the world populaton of tb. speces. Ths relatvely re.trcted dstrbuton of ha~lout stes s tbought to be related to nearby oceanographc features. Lloyd et ale (1981) speculated tbat the feedng babtats of all fur seall, not just those n tbe Berng Sea (Perez 1979, Perez and Bgg 1980), consst of the outer contnental shelf and oceanc domans, and tbat "only slands n or ldldedate1yadjacent to the (very productve and food-rcb] outer shelf domans are sutable for fur seal rookeres." Patterns of Occupancy at Baulout Stes Bgg (1986) conducted a detaled nvestgaton of the rather complex patterns of arrval and departure of northern fur seals at haulout stes on St. Paul sland n the Prblofs (see dscusson above). Arrval and departure patterns on St. Paul probably are also representatve of arrval and departure patterns on St. George sland, also n the Prblofs (M. Bgg, pers. comm, 1987). Northern fur seals occupy haulout stes at dfferent -tmes dependng on

31 Results ls.-u.s.s.r. '...'. "... ~...,, {.:.:" :>.".,'. ". ~... 6<0...SE:RNG SE:A ALASKA.0 00",... 6()0 ~(.t... : '"".... :.~t.p:u. "':.. '. St:~: "<::.', ':.',.... o ~."..~ ", ::.:..:. 2000", ( 0 PACFC OCE:AN.. Fgure 3. Locatons of northern fur seal haulout stes n the Berng Se a, Alaska.

32 Results 16 ther sex and age. n general, the oldest and strongest bulls return frst. followed by younger bulls and adult females. followed by even younger bulls and females (Table 1). The fnt bulls begn arrvna at Prbtof s 1and rookeres n early to ad-hay and usually abandon ther terrtores by md-august. Pregnant females begn arrvng n md-june. Females usually gve brth wthn a day of arrvng at the rookery, but t. not unusual for some females to gve brth up to three days after arrvng. The peak of puppng s n early July (Fscus 1986). Pups are nursed untl the female breeds S~6 days after gvng brth (Gentry and Bolt 1986). Females then return to sea to feed for several day. (aean 3.5 days, Loughln et ale 1987). Ths s the frst perod of feedng by females after ther arrval at the rookery. The female contnues to come and go to and from the rookery for about 120 dars (Gentry and Bolt 1986). She travels to sea for perods averagng 5.7 days n July and 7.3 days n August; each feedng perod s followed by two days of nursng - (mean days accordng to Loughln et ale 1987.and Gentry and Bolt Table 1. Summary of the tlmlng of arrval of haulng grounds and rookeres by northern fur seals of dfferent ages and sexes, St. Paul sland. Berng Sea, Alaska (from Blg 1986). Sex Ste* State** Age Date of Last Arrval*** Abundance Male Female R 1 Late Sep to early Oct Few BG 2 Hd-to late Aug 2 yr >1 yr BG 3 Late Jul 3 yr >2 yr BG 4 Hd-Jul all BG 5 Late Jun to early Jul all BG 6 Late Jun all R >7 Late Jun all R HP 1 Oct to early Hov Few BG,R HP 2 Hd-to late Sep 2 yr >1 yr -BG HP >3 Hd-Aug 3 yr >2 yr BG P >4 Hd-Aug all R P >4 Md-Jul all * R rookery; BG haulng ground. ** NP not pregnant; P pregnant. *** Date when essentally all seals have arrved.

33 Results 17 re.pectvely). Th. proce contnue. untl the pup. are weaned. Adult females start to leave the rookeres n early October (G.ntry 1981) and departure contnuel nto November (Table 2). Pup. fr.t enter the.ea at about 4-6 weeks of age, but may reman at the rookery untl early November (Flcul 1986). ' Table 2. A swlllllaryof the occupancy of haulout ste. on the Prblof t.land., Berng Sea, Ala.ka, by dfferent age and lex cla of northern fur.all. May Jun Jul AU Sep.Oct Nov Dec Breednl Bull. 1* 2 3 Adult Female Subadult Male Subadult Female Pup * '1' n the tme lne ndcat the ap~rox t arle.t dates of arrval, '2' ndcate. the approxmate date of abandonment of terrtores by adult bull. and breakdovn of the socal structure of the rookery, and '3' ndcate. the be,nnng 9f the departure of fur seal. fro. th..land. and the.tart of the.outhbound mgraton. The 3 to S-year-01d male. beln to haul out on the haulng grounds n late June, and younler antmals contnue to arrve well nto September. The late.t arrvals nclude many 2-year-old Altboull lo.t yearlngs reman at sea and do not return to haulout st, a few yearlnl fe le. may make bref vst. to tle perphery of rooker or haulnl grou~d late as early Noveaber._ Locaton and Statu' of Northern Fur Seal Baulout Ste. 'rblof.land. t. P_l 1.1 There are 14 dstnct haulout stes (rookeres wth assocated haulng grounds) on St. Paul sland (Table 3; Appendx 2; Kozloff 1985). The hstory of use of these haulout ste. (Table 3) shows a general declne n the number of breedng bulls and pups snce the 1950's. The ~ost

34 Results 18 Table 3. P.hul_ ofjllldbml far 1el!D!jor hllllaaula (ad aeloobrea) n de Berna Sea, AJuka., 1950'.* 1960'.* 1970'.* 1980's** Currau HauoutSe (Rookay) Bleed. Paps Bleed. 1M Breed. Lve Breed. Pup Breed. Pups Bull Bam Bulls Pup! Bull Pup! BuD (EsL)t BuUs (EsL)t SL Geo. d 1958* 1961* 1966* 1979* 1973* 1984" 1984" 1986-* Zpdn ' South Nonh 985 No EutReef 212 Da ' ElatClft Slraya-Anl 426 ' SUBTOTAL S SL, &ud * 1961* 1961* 1978* 1915* 1984" 1984" 1987* Lukaan wkjdy a Kov Gorbardl Ardpl 119 No 153 whtsf Reef MorjoY S 8416 VOl&DChn 1568 SpKfc Llle PoJo na ~ PooYDaClft wlpolorda PolOYDa 291 Da S Tollro Zpda Reef Llle l.pa Zpdn SUBTOTAL Svak" 1968* 1966* 1979* 1970'.tt 1980's 1980'stt 1980's 1980'stt zeooo BOOlloy No Da No Da NoDlla No 0. NoDala NoDlla 1980** 1980* s.ad GRAND TOTAL Hole: dll ll b Wle na mmy dffndt yam may DOthaft bem caeced ll syfadc 1er ' 1960'1 ad 1910'. dlae &am LDder (1980). -* 1980'.'" 'C1rNl'cla &am Lloyd et'" (1981), Kozoff (1986) ad NMFS m. t Esdm_ of pap pmcuc:cad baed Gltba nto-bnedda BuD : Pup- 1 : (Cozoff 1986:11). tt Recel pap prodaccllglswch (Lder Kajmura 1982:322). Est. ofleclllll Bnedaa Bull QlSwrdl baedoa dlerllo Breedn& BullJ:Pup-l:34.35 (Kozloff 1986:11).

35 Result. 19 current e.d te. ndcate that about 124,500 pup. (plu. at least the same number of adul.t fe le.) and about 3600 harea buu. u.ed theae 14 haulout stes durng 1987 (NMFS fle data) t~. Th. baulout.te. located on a 11.land about 0.5 km S of St. Paul sland (S of tbe rookery at Reef; Appendz 2). Jordan and Clark (1898) reported about 6000 fur 'eal. durng nvestlaton. tbere late n the last century, and Lander and Cajaura (1982) ndcated tbat the rookery at ths baulout.te produce. about 20,000 pup. eacb year. t. Georp 1.1 There are.z d.tnct baulout ste. on St. George sland (Appendx 2; tozloff 1985). A declne n the number of breedng bulls and pups smlar to that recorded on St. Paul.land. also evdent on St. George.land (Table 3). The mo.t current e.t te. ndcate that about 48.~00 pups (plu. at lea.t the.ame number of adult fe!ule.) and about 1400 harem bull. u.ed the.e 6 haulout ste. durnl 1986 (NMlS fle data). BOlol1of aland BOloslof.land s volcanc n orln; t ro.e fro. tbe sea about 65 km nortb of Umnak.land n tbe ea.tern Aleutans on 18 May 1796 (Orth Byrd et al. 1980; see Appendx 2). Today t. ab9ut 1.5 km lonl, and supports a very 11 number of reproductvely actve northern fur seals (Table 3). Neverthele, tbe number of fur.eal. u.nl tb. baulout ste has grown snce 1980 (Lloyd et al. 1981). The most current est te. ndcate that 14 northern fur seal pupa (plua- tb number of adult fe les) and 7 harem bulls used tb. ste durq 1984 (RKrS fle data) Northern Sea Lon (Eumatopa. jubatus Schreber) Background The northern or SteUer sea lon belongs to the famly of eared seals (OtarUdae). The northern sea lon s the larlelt of the eared seals. w t h some bulls exceednl 3 m n length and 1000 kg n welht. Ths speces breeds along the west coast of North Amerca from the southeastern Berng Sea and the

36 Results 20 Aleutan slands to southern Calforna. t also breeds n Asa on the Kurle slands. n the. Sea of Okhotsk and on the Kamchatka Pennsula (Gentry and Wthrow 1986, Lough~n et ale 1987; Hoover 1988a). Kajor breedng concentratons of thl speces n North Amerca occur manly n the northwest Gulf of Alaska and the Aleutan sland.; Forrester sland, off S! Alaska, s also a major rookery. Fgure 4.how. the general dstrbuton of ths speces n the eastern Berng Sea. Smlar to fur leal., the brth and the nurtu~ng of pup. and breedng by northern sea lonl occurs on tradtonal, well e.tablshed rookeres. As mentoned earler, however, northern sea 1on. may haul out throughout the year (at dfferent ste.), rather than only durng the breedng se88on. Neverthelesa, there are defnte seaaonal peaks n haulout actvty. The annual dstrbuton of northern sea lons a such that more males are seen along the north coast of North Amerca durng ynter than durng summer; ndvduals from Calforna marate northward durng wnter and return south n summer. Smlarly, juvenle males from haulout stes n the Aleutan and Prblof sland. marate north nto the central and northern Berng Sea n late aummer, tben return.outh as ce begn. to form.. The maxmum sze of tbe nortbern sea lon populaton for the perod was estmated to be about 290,000 ndvduals (some pups ncluded); more than 196,000 (67.6%) of ths total were counted n Ala.ka (Loughln et a ). The number. of northern sea lon. counted n Alaska durng apparently was unchanged snce.urveys n by Kenyon and Rce (1961) and!lathben and Lopp (1963). However, there had been a. sgnfcant sbft n ther dstrbuton. Fewer sea lons were usng haulout stes n the eastern Aleutans (Braham et ale 1980), and more were usng haulout ste. n the central and western Aleutans (Fscus et a ). Snce 1980 there have been further sgnfcant declnes n the number of northern sea lons at aost stes n Alaska. The area from the central Aleutan slands (Kska sland eastward) to the central Gulf of Alaska (Sugarloaf and Marmot slands, north of Afognak sland) has been studed more systematcally than most other ar&as.of A1aaka (see