The Gray Whale,Eschrichtius robustus

DALE W. RICE, ALLEN A. WOLMAN,and HOWARD W. BRAHAM

Introduction

The gray whale, Eschrichtiusrobustus (LilIjeborg, 1861), is readilyrecognized by its mottled gray colorand lack of a dorsal fin. Instead ofthis fin, it has a low hump, followedby a series of 10 or 12 knobs along thedorsal ridge of the tail stock; these areeasily seen when the animal arches todive. The adult gray whale is 36-50feet long and weighs between 16 and45 tons.

The gray whale is currently con­fined to the North Pacific Ocean (Fig.1). Because it uses coastal habitats ex­tensively, the gray whale was especial­ly vulnerable to shore-based whalingoperations. Two stocks occur in theNorth Pacific: The "California" or

eastern stock which breeds along thewest coast of North America, and the"Korean" or western stock which ap­parently breeds off the coast ofeastern Asia (Rice and Wolman,1971). Both stocks were severelydepleted by the early 1900's. Underlegal protection, the eastern stock hasrecovered substantially - one of thefew stocks of great whales to do so.The western stock has not recovered.The gray whale formerly occurred inthe North Atlantic (van Deinse andJunge, 1937; Cederlund, 1939; Fraser,

The authors are with the National MarineMammal Laboratory, Northwest and AlaskaFisheries Center, National Marine FisheriesService, NOAA, 7600 Sand Point Way N.E.,Bin C15700, Seattle, WA 98115.

1970; Mitchell and Mead I), but hasbeen extinct there for several cen­turies.

Distribution and Migration

Eastern North Pacific

Most of the California stock spendsthe summer feeding, mostly in thenorthern Bering and southern ChukchiSeas (Pike, 1962; Rice and Wolman,

'Mitchell, E. D., and 1. G. Mead.1977. History of the gray whale in the AtlanticOcean. (Abstr.) In Proceedings of the 2ndConference on the Biology of Marine Mam­mals, San Diego, California, 12-15 December1977, p. II. (Available from first author, ArcticBiological Station, Department of Fisheries andOceans, 555 SI. Pierre Blvd., Ste. Anne deBellevue, Quebec, H9X 3R4, Canada).

120' E 150' E 180' 150'W 120'W 90'W 60'W 30'W O'

Figure I. - Geographic distribution of the gray whale. Simple hatching indicates the summer feeding grounds.Small dots indicate the migration routes. Stippling indicates the winter grounds. In the Atlantic, the gray whale hasbeen extinct for at least several hundred years; early historical records are indicated by large dots, subfossil finds bytriangles. Perhaps extinct is the population that formerly spent the winter in southern Japan (large dot).

46(4),1984 7

A new~orn gray whale calf in Laguna Ojo de Liebre, Baja California, Mexico.Each dimple on the snout and lower lip marks the site of a hair. Photo by D.W. RIce.

1971; Bogoslovskaya et al., 1981). Anunknown number of individuals sum­mer along the west coast of NorthAmerica in apparently isolated loca­tions south of Alaska from VancouverIsland, Canada, as far south as BajaCalifornia, Mexico (Patten andSamaras, 1977; Sprague et al., 1978).In the Beaufort Sea, sightings havebeen made of small groups as far eastas long. 1300 W during August (Rughand Fraker, 1981); in the East SiberianSea, gray whales were found along theSiberian coast as far west as 174°08'Ein late September (Marquette et. al.,1982).

In October and November, thestock begins leaving the Chukchi Sea,exiting the Bering Sea through UnimakPass, Alaska, mainly in November andDecember (Rugh and Braham, 1979;Braham, 1984; Rugh, 1984). Thewhales migrate near shore along thecoast of North America from Alaskaall the way to central California (92percent pass within 1.4 km of CapeSarichef, Unimak Pass, and 94 percentpass within 1.6 km of the Monterey­Point Sur area of central California).After passing Point Conception,Calif., the majority take a more directoffshore route across the southernCalifornia Bight to northern BajaCalifornia. Southbound migratinggray whales swim at about 7.7kmlhour, and thus travel about 185km per day (pike, 1962).

Migrating gray whales are temporal­ly segregated according to sex, age,and reproductive status (Rice andWolman, 1971). During the southwardmigration, the sequence of passage offCalifornia is as follows: Females in latepregnancy, followed by females thathave recently ovulated, adult males,immature females, and then immaturemales. The earliest southboundmigrants (mostly late-pregnantfemales) usually travel singly, whereaslater migrants usually are in pods oftwo or more. The mean pod sizethrough Unimak Pass is about two.

This stock winters mainly along thewest coast of Baja California. Thepregnant females assemble in certainshallow, nearly landlocked lagoonsand bays where the calves are bornfrom early January to mid-February.

8

The major calving areas are LagunaGuerrero Negro (with 9 percent of thecalves), Laguna Ojo de Liebre (53 per­cent), Laguna San Ignacio (IIpercent), and Estero Soledad (12 per­cent). Minor calving areas (each with< 6 percent) are San Juanico Bight,Bahia Magdalena, Bahia Almejas, andBahia Santa Marina (Rice et al., 1981).Calving rarely occurs during the south­bound migration north of BajaCalifornia (Rice and Wolman, 1971;Sund, 1975). A few calves are alsoborn on the eastern side of the Gulf ofCalifornia at Yavaros, Sonora, andBahia Reforma, Sinaloa, Mexico(Gilmore, 1960). Contrary to manypublished statements, there is noevidence that San Diego Bay, Calif.,was ever a calving area (Henderson,1972). Recent studies have revealedthat the vast majority of gray whales inBaja California (other than cows withcalves) spend the winter outside thelagoons in Bahia Sebastian Viscainoand Bahia de Ballenas (Rice et al. 2).

The northbound migration beginsin mid-February, and by April whalesbegin showing up in the southern Ber­ing Sea, which they enter through

'Rice, D. W., A. A. Wolman, and D. E.Withrow. 1984. Distribution and numbersof gray whales on their Baja California wintergrounds. Unpub!. manuscr. Nat!. Mar.Mammal Lab., Nat!' Mar. Fish. Serv., NOAA,7600 Sand Point Way N.E., Bin CI5700, Seat­tle, WA 98115.

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Unimak Pass (Braham et aI., 1977;Braham, 1984). This migration iscompletely coastal, at least to the eastcentral Bering Sea (Nunivak Island).Most animals in Alaska travel withinI km of the coast, especially in thesoutheastern Bering Sea, and at leastsome apparently feed during migra­tion (Braham, 1984). During thenorthward migration, the sequence isas follows: Newly pregnant females,followed by anestrous females, adultmales, and immature males andfemales; cows with calves are the lastanimals to leave the lagoons, andmost migrate after the other whales.The peak of the migration passesPoint Piedras Blancas, Calif., about IMay (Poole3).

Western North Pacific

The Korean stock formerly oc­cupied the northern Sea of Okhotsk inthe summer, as far north as Penzhin­skaya Bay, and south to Akademiiand Sakhalinskiy Gulfs on the westand the Kikhchik River on the east.Southbound whales migrated alongthe coast of eastern Asia to winter

'Poole, M. M. 1981. The northward migra­tion of the California gray whale, Eschrichtiusrabustus, off the central California coast.(Abstr.j In Proceedings of the 4th Biennial Con­ference on the Biology of Marine Mammals,December 14-18, 1981, San Franc., Calif., p.96. (Available from author, Biology Depart­ment, Sonoma State University, Rohnert Park,CA 94928.

Marine Fisheries Review

Circular mud plume pattern produced by a feeding gray whale in the northernBering Sea. This behavior is believed to be associated with the whale returningto the location it was just at to resume feeding. Photo by H. W. Braham.

calving grounds off the south coast ofKorea, passing Ulsan from lateNovember to late January. Until theturn of this century, another migra­tion route led down the eastern side ofJapan to winter grounds in the SetoInland Sea, Japan (Omura, 1974).Nishiwaki and Kasuya (1970) andBowen (1974) hypothesized that threerecent records of gray whales in Japaninvolved vagrants of the Californiastock rather than being Korean stocksurvivors. It is likely that any rem­nants of the Korean stock are in suchlow numbers (Brownell, 1977) as to bebelow a critical population size suffi­cient for recovery. This stocktherefore may be almost extinct.

Life History and Ecology

Feeding

Gray whales are predominantlybottom feeders that apparently ingesttheir food by suction (Ray andSchevill, 1974); only rarely do theyfeed in midwater or at the surface. Ontheir summer grounds in the shallow

46(4),1984

waters of the Chukchi and BeringSeas, they feed primarily on benthicgammaridean amphipods. Forty­three species have been identifiedfrom stomachs, but, depending onarea, one of seven species is usuallydominant (Pontoporeia femorata, P.affinis, Anonyx nugax, Ampeliscamacrocephala, A. eschrichti,Nototropis brueggeni, or N. ekmam).In some areas polychaete worms aretheir main food. Incidentally ingestedbenthos include gastropods, asci­dians, bivalves, priapulids, decapodcrustaceans, isopods, sipunculids,hydrozoans, anthozoans, cumaceans,holothurians, sponges, and fish (Am­modytes sp.) (Zimushko and Len­skaya, 1970; Bogoslovskaya et aI.,1981). Gray whales may play an im­portant role in the rate of turnover ofthe epibenthos on their summerfeeding grounds (Nerini and Oliver,1983; Nerini, 1984).

Little if any food is consumed dur­ing the southbound migration off theU.S. continental coast, although rare­ly small quantities of decapod nauplii

Aerial view of a feeding gray whalesurfacing in the northern BeringSea, near St. Lawrence Island,Alaska. Note the heart-shaped blowand the trailing mud plume causedwhen the whale expells water anddebris out the side of its mouthwhen surfacing after feeding onorganisms along the bottom of thesea. Photo by H. W. Braham.

9

(Pachyche/es rudis and ?Fabia sp.) areeaten (Rice and Wolman, 1971).There are reports that they do feed tosome extent just before (Sund, 1975)and while on their winter grounds offBaja California (Swartz and Jones,1982) although the frequency of thisbehavior is unknown. In the intervalbetween their southward and north­ward migration past San Francisco,the whales without calves lose from0.21 percent to 0.37 percent of theirbody weight per day. This weightreduction is sufficient to account forthe estimated energy expenditure dur­ing the winter. Blubber thickness andoil yield also decrease during winter.Apparent feeding has been observedduring the northbound migrationbeginning in southeastern Alaska(Braham, 1984), but again the fre­quency and quantitative evidenceassociated with energy expenditurefor this is unknown.

Reproduction

Females attain puberty at anestimated mean age of 8 years (range,5-11 years) and a mean body length ofabout 11.7 m (see Rice and Wolman(1971) for additional details onreproduction).

Female gray whales normally comeinto estrus biennially in lateNovember and early December. Mostindividuals ovulate only once eachseason, although whales failing toconceive after their first ovulationmay experience a second estrous cyclethe same season. Multiple ovulationsare extremely rare. Mean ovulationrates are 1.20 per breeding season fornulliparous females and 0.96 perbreeding season (0.52 per year) forparous females. There is littleevidence of postpartum ovulation orof ovulation at any other time of theyear. However, increase in follicle sizefollowing stillbirth or early loss of thecalf suggests that females mightovulate following such an event.

Most conceptions occur within a3-week period during southwardmigration, with a peak about 5December; a few occur as late asJanuary on the winter grounds. Thepregnancy rate is 0.86 per breeding

10

season or 0.46 per year. The period ofgestation is about 13.5 months; fetalgrowth accelerates during the last halfof pregnancy and decelerates justbefore birth (Rice, 1983). Duringsouthward migration, late pregnantfemales (exclusive of their conceptus)average 25-30 percent heavier thanother adult females. Most births occurwithin a period of 5-6 weeks, with apeak occurring about 27 January; ex­treme recorded dates are 26 Decemberto 1 March (Swartz and Jones, 1983).

Lactation lasts an average of about7 months, ending in August. Femalesare usually in anestrus from August toNovember or December. However,females that fail to ovulate or con­ceive during the winter are probablyin anestrus for the following 12months.

Males attain puberty at anestimated mean age of 8 years (range,5-11 years) and a mean body length ofabout ILl m. The average weight ofthe testes of adult males duringsouthward migration in Decemberand January is 38 kg, and the meandiameter of the seminiferous tubulesis I77/-tm. During northward migra­tion in February and March, meantestes weight and tubule diameter are22 kg and 148 fllll, respectively.From July through October, the testesaverage 23 kg. These differences sug­gest a marked seasonal sexual cycle inthe male, with a peak of sperma­togenetic activity in late autumn orearly winter.

Natural Mortality

No infectious diseases have beenreported in gray whales. Epizoites ofgray whaies include the following(percentage of occurrence in paren­theses) (Rice and Wolman, 1971): Thebarnacle Crypto/epas rhachianecti(100) and the cyamids Cyamus scam­moni (99.7), C. ceti (99.4), and C.kess/eri (98.1). Endoparasites includethe trematodes Lecithodesmus goliath(0.6), Ogmogaster penta/ineatus(> 22), and O. antarcticus (33); twoapparently undescribed species of thecestode Priapocepha/us, one in thesmall intestine (30) and the other inthe large intestine (0.3); the nematode

Anisakis simp/ex (0.3); and twoacanthocephalans, Corynosoma sp.(5.7) and Bo/bosoma sp. (0.3). Ob­vious pathogenic effects are producedonly by the liver fluke Lecithodesmusgoliath, but it is not known whetherthis ever causes mortality.

The killer whale, Orcinus orca, ap­pears to be the only predator on graywhales. Evidence from necropsy of 39gray whales that stranded on St.Lawrence Island indicated that 16 hadbeen killed by killer whales (Fay et aI.,1978). The mortality rate from killerwhale attacks is unknown. However,the frequency of tooth scars on graywhale carcasses indicates that killerwhale attacks are often unsuccessful.

Moderate numbers of gray whalecalves strand in and near the nurserylagoons (Swartz and Jones, 1983). Afew adults strand every yearthroughout the range, but the numberseems low compared with the size ofthe population. Rates of mortalitydue to stranding cannot be calculated.

Total annual mortality estimatesfor animals older than 8 years,calculated from the age compositionas determined by ear-plug readings,were 0.095 for females and 0.081 formales; a similar estimate for sexuallymature females, based on ovariancorpora counts, was 0.082 (Rice andWolman, 1971). These estimates areprobably biased upwards because thepopulation was increasing during the1950's and 1960's when the data werecollected. Reilly (1981) estimated theadult natural mortality rate at 0.056and the juvenile mortality rate at0.132 during that period. The sexratio is essentially equal throughoutlife.

Exploitation and Population Size

History of Exploitation

Eskimos living on the shores of thenorthern Bering Sea and the ChukchiSea have hunted whales for perhapsseveral thousand years. In Alaska, thecatch is mostly of bowhead whales,Ba/aena mysticetus, with very fewgray whales taken, usually less thanone per year (Marquette and Braham,1982). However, on the Chukotka

Marine Fisheries Review

Table 2.-Catches of California gray whales by modern·style whaling, 1913·47'

11

Baja Bering andYear California California Washington Alaska' Chukchi Seas' Total

'Data summarized from Rice and Wolman (1971), except that the figures for 1943, 1946,and 1947 have been changed to agree with those in Kleinenberg and Makarova (1955).'Gulf of Alaska (shore stations at Port Armstrong and Port Hobron).'Peiagic whaling.

119

Between 1959 and 1969, 316 graywhales were killed under SpecialScientific Permits off California.From 1966 to 1969 the combinedscientific and U.S.S.R. catchesaveraged 221 per year.

Current andInitial Stock Sizes

Scammon (1874) estimated that theCalifornia gray whale population wasprobably not over 30,000 in1853-1856, and that by 1874 thenumber did not exceed 8,000 or10,000. After a careful analysis of thehistorical data, however, Henderson(1972) concluded that the populationdid not exceed 15,000-20,000 prior tothe initiation of commercial exploita­tion in 1846.

In 1885-86, Townsend (1887)estimated that only 160 gray whalesmigrated south past San Simeon,Calif. Andrews (1914) wrote that "Forover 20 years [preceding 1910] thespecies had been lost to science andnaturalists believe it to be extinct."Howell and Huey (1930) said it was

19

1100 33 133

41 1 4229 3 329 1 122 2

2 454 5434 34

102 10214 1454 5429 29

105 10557 57

101 10199 99

30 30

1947

19131914

1945

192019211922

192419251926192719281929

19331934193519361937193819391940194119421943

America also may have taken a fewgray whales (Mitchell, 1979).

From 1846 until about 1900,American whalers exploited graywhales mostly on their winteringgrounds, but also took a few in north­ern waters during the summer. On thebasis of available historical records,Henderson (1972) estimated that thetotal catch from 1846 to 1874 wasabout 8,100. During the peak of thisfishery from 1855 to 1865, the annualcatch averaged 474 whales. Catchesduring the three winter seasons from1883-84 to 1885-86 were 58, 68, and41, respectively (Townsend, 1887).

Modern-style whaling began on thewest coast of North America in 1905.A few gray whales were taken in thewinter off Baja California andCalifornia, mostly between 1925 and1929. Factory ships took an averageof 48 gray whales per year in the Ber­ing Sea from 1933 to 1946 (Table 2),after which commercial whaling forgray whales was banned by the Inter­national Convention for the Regula­tion of Whaling.

Table 1.-Catches of California gray whalesby aboriginal whaling, 1948·82.

Year U.S.S.R.' Alaska' Total

1948 19 191949 26 261950 10 111951 12 131952 42 44

1953 37 1 381954 38 3 391955 59 591956 121 1221957 95 96

1958 145 3 1481959 187 6 1931960 156 1561961 207 2081962 147 147

1963 178 1 1791964 188 2 1901965 175 1 1761966 194 1941967 125 125

1968 135 1351969 139 1401970 146 1511971 150 1531972 181 182

1973 173 1731974 181 1841975 171 1711976 163 1631977 186 187

1978 182 2 1841979 178 4 1821980 179 3 1821981 135 0 1351982 160 4 184

'Data from Ivashin and Mineev (1978) andwith addition of figures for 1978·82 from un·published data of the AII·Union Research In·stitute of Marine Fisheries and Ocean·ography (VNIRO), Moscow.'Data from Marquette and Braham (1982):and unpublished data of the National MarineMammal Laboratory. Actual values may below because the taking of gray whales isoften not reported.

46(4),1984

coast of the U.S.S.R. the catch hasbeen almost entirely gray whales.Since 1969 gray whales have beentaken by the Soviet Government forthe Chukchi Eskimos using onemodern-style catcher boat (Ivashinand Mineev, 1981). The totalaboriginal catch since 1967 has aver­aged about 165 gray whales per year(Table 1). The current catch limit setby the International Whaling Com­mission (IWC) is 179 per year.

Several Indian tribes on VancouverIsland and in the State of Washingtontraditionally hunted gray whales, buthave not done so since 1928. Indiansfarther north along the coast of North

18

16

"0 14

~12"0

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c:'2

'""0-0"-

1~00 1810 1820 1830 1840 1850 1860 1870 1880 1890 1900 1910 1920 1930 19'10 1950 1960 197 0 1980

Year

Figure 2. - Gray whale population t~ajectory based on an. e~timatedmaximum population size of 24,000 pnor to 1800 and an abongmal takethrough that time of 600 whales per year. Peaks and vall~ys relate toperiods of heavy exploitation and recovery froll? commercIal whalIng.This modeling best fits the current populatIon census of about16,000±3,000 (from Reilly, 1981).

present is shown in Figure 2. Resultsof these assessments suggest that thepopulation has not increased to thelevel that it would reach if there wereno current exploitation. The popula­tion has recovered, however, to thelevel (which was presumably stable)that it was at before commercial whal­ing began in the mid-19th century.

Reilly (1981) estimated the max­imum sustainable yield (MSY) as 480gray whales per year; however, in arecent revision, he gave a newestimate of 320 per year, which wouldoccur at a population size of 11,380whales5 • His revised model alsopredicted that, under an annual takeof 180 whales per year, the populationwould reach 19,000 by the year 2150and continue rising slowly thereafter,achieving stability at a level of 19,620.

" .. doubtful whether more than afew dozen individuals survive."However, K. W. Kenyon4 says that hecommonly observed gray whalesmigrating past La Jolla, Calif., duringthe 1930's.

Systematic shore counts of thesouthward migration were initiated atSan Diego, Calif., in 1952-53, andcontinued intermittently until 1976-77(Gilmore, 1960; Rice, 1961). Thesecounts indicated a steadily increasingpopulation until 1959-60.

From 1967-68 to 1973-74, a shorecount was made every winter atYankee Point near Monterey, Calif.where 90 percent of the whales passwithin 2 miles of shore and boat traf­fic is at a minimum. From 1974-75 to1979-80 the count was made atGranite Canyon, 4 miles south ofYankee Point. A census of thepopulation leaving the summerfeeding grounds was made from 1977to 1979 at Unimak Pass.

The 1977 estimate of the popula­tion leaving the Bering Sea was 15,099± 2,341 (Rugh and Braham, 1979),and for the 3 years 1977-79 Rugh(1984) estimates 17,000. The popula-

4K. W. Kenyon, 11990 Lakeside Place N.E.,Seattle, WA 98125. Pers. commun.

12

tion size in 1979-80 off California wasestimated at 15,647 (95 percent con­fidence interval of 13,450-19,201); therate of annual net increase (less the1.2 percent harvest mortality) duringthe preceding 13 years was 2.5 per­cent, with a standard error of 0.96(Reilly et aI., 1980; Reilly, 1981; Reillyet aI., 1983). This indicates that theeastern North Pacific population hasrecovered to, or now exceeds, its sizeprior to commercial whaling.

Computer simulation models of thegray whale population size from 1800through 1980 were run by Reilly(1981). Various forms of dynamicresponse of vital parameters topopulation density were used, as wellas various carrying capacity levels,and various levels of prehistoricaboriginal removal rate. The modelthat produced a population trajectoryin best agreement with the census dataand historical evidence indicated thatthe carrying capacity (or maximumpopulation size historically) may havebeen 24,000, and that the populationhad been reduced to below 12,000 bythe year 1800 as a result of aboriginaltakes which may have averaged 600whales per year (Reilly, 1981). Thepopulation trajectory generated bythis model for the period 1800 to the

Management

One potential threat to the Califor­nia gray whale population may be in­creasing industrial development andvessel traffic in the calving lagoonsand in other vital habitats along themigration route and on the feedinggrounds. In the recent past, con­siderable harassment has been causedby commercial cruise boats whichtake people into the calving lagoons tosee the whales and by small pleasurecraft brought overland down the newBaja California highway. Harassmentnow may be under better control thanin the past. Under existing U.S. laws,regulation and enforcement are beingdefined and steps taken to controlvessels that interfere with gray whaleson their migration path. Between1972 and 1979, the Mexican Govern­ment designated three of the five ma­jor calving lagoons in Baja Californiaas gray whale refuges (Reeves, 1977;Swartz and Jones, 1982). These arethe lagoons visited by most of theU.S. tour boats and private tourists.The number of vessels allowed in thelagoons at anyone time is limited,

'Reilly, S. B. 1984. Future trends in graywhale population size. Unpubl. manu~cr.

Southwest Fisheries Center, Natl. Mar. FIsh.Serv., NOAA, P.O. Box 271, La Jolla, CA92038.

Marine Fisheries Review

Estudios Economicos y Sociales del TercerMundo, Mexico. [In Span.]

Fay, F. H., R. A. Dieterich, L. M. Shults, andB. P. Kelly. 1978. Morbidity and mortali­ty of marine mammals. In Environmentalassessment of the Alaskan continental shelf.,Annual Reports 1:39-79. U.S. Dep. Com­mer., Natl. Oceanic Atmos. Admin., En­viron. Res. Lab., Boulder, Colo.

Fraser, F. C. 1970. An early 17th centuryrecord of the California gray whale in Icelan­dic waters. Invest. Cetacea 2: 13-20.

Gard, G. 1974. Aerial census of gray whalesin Baja California lagoons, 1970 and 1973,with notes on behavior, mortality, and con­servation. Calif. Fish Game 60:132-143.

Gilmore, R. M. 1960. A census of the Cali­fornia gray whale. U.S. Fish Wildl. Serv.,Spec. Sci. Rep. Fish. 342, 30 p.

Henderson, D. A. 1972. Men and whales atScammon's Lagoon. Dawson's Book Shop,Los Angeles, 313 p.

Howell, A. B., and L. M. Huey. 1930. Foodof the gray and other whales. J. Mammal.II :321-322.

Ivashin, M. V., and V. N. Mineev. 1978. 0sastoyanii zapasov serykh kitov (The state ofthe gray whale stock.) Rybn. Khoz.3:15-17. [In Russ., Transl. by S. Pearson,Natl. Mar. Mammal Lab., Nat. Mar. Fish.Serv., NOAA, Seattle, Wash., 1979,7 p.]

--::--:-__, and 198 I. Thehistory of gray whale harvesting offChukotka. Rep. Int. Whaling Comm.31 :503-505.

Kleinenberg, S. E., and T. I. Makarova(editors). 1955. Knitboinyi promysel Sovet­skogo Soiuza (The whaling industry of theSoviet Union). Izd. "Rybnoe Khozyaistvo",Moscow, 117 p. [In Russ.)

Marquette, W., and H. Braham. 1982. Graywhale distribution and catch by AlaskanEskimos: A replacement for the bowheadwhale? Arctic 35:386-394.

____, M. K. Nerini, and

Literature Cited

A gray whale, raising its barnacle encrusted head above the surface of LagunaOjo de Liebre in Baja California, reveals its paired blowholes. Photo by D. W.Rice.

virons remains an important conser­vation measure.

Andrews, R. C. 1914. Monographs of thePacific Cetacea. I. The California graywhale (Rhachianecles glaucus Cope). Mem.Am. Mus. Nat. Hist. (New Ser.), 1:227-287.

Bogoslovskaya, L. S., L. M. Votrogov, andT. N. Semenova. 1981. Feeding habits ofthe gray whale off Chukotka. Rep. Int.Whaling Comm. 31:507-510.

Bowen, S. L. 1974. Probable extinction ofthe Korean stock of gray whale (Eschrichliusrobuslus). J. Mammal. 55:208-209.

Braham, H. W. 1984. Migration andfeeding of gray whales (Eschrichliusrobuslus) in Alaska. In M. L. Jones, S. L.Swartz, and J. S. Leatherwood (editors), Thegray whale, p. 249-266. Acad. Press, N. Y.

--::--:--c--' C. Fiscus, and D. Rugh. 1977.Marine mammals of the Bering and southernChukchi Seas. In Environmental assess­ment of the Alaskan continental shelf. An­nual Reports 1: I-99. U.s. Dep. Commer.,Natl. Oceanic Atmos. Admin., Environ. Res.Lab., Boulder, Colo.

Brownell, R. 1977. Current status of the graywhale. Rep. Int. Whaling Comm. 27:209­211.

Bryant, P., and C. Lafferty. 1980. The graywhales of Guerrero Negro. Whalewatcher14(4):3-5.

Cederlund, B. A. 1939. A subfossil graywhale discovered in Sweden in 1859. ZooI.Bidr. Upps. 18:269-285.

Cordoba, F. 1981. La ballena gris y laexplotacion de fosfora en Baja California Sur(The gray whale and the exploitation ofphosphorus in southern BajaCalifornia). In Ballena Gris. Centro de

6Tyack, P., C. Clark, and C. Malme. 1983.Migrating gray whales alter their motion inresponse to sounds associated with oil develop­ment. (Abstr.) In Proceedings of the 5th Bien­nial Conference on the Biology of MarineMammals, November 27-December I, 1983,Boston, Mass., p. 104. (Available from firstauthor, Woods Hole Oceanogr. Inst., WoodsHole, MA 02543.)

and entry into certain areas is forbid­den. Thousands of tourists and amultimillion-dollar industry resultfrom these activities.

Oil and gas exploration is con-templated or under way on the con­tinental shelf from California to theBeaufort Sea, throughout the migra­tion range of this species. Annually,the gray whale population migrates byor through at least eight oil lease areasin U.S. waters alone. On the wintercalving grounds, exploratory areas in­clude sites within and adjacent topresent calving and rearing areas,such as the offshore waters of Viz­caino Bay, where seismic explorationfor gas deposits took place duringspring 1981. The effects of oil pollu­tion on the benthic organisms onwhich these whales feed are unknown.Little is known about what effects, ifany, other activities associated withcoastal development might have; cer­tain man-made sounds cause migrat­ing whales to deviate from theircourse (Tyack et al. 6).

Past industrial activities haveshown some impacts. For example, inthe calving lagoon of GuerreroNegro, daily dredging and vessel traf­fic caused the whales to abandon thearea from 1957 to 1967. The whalesdid not return until 6 years after suchoperations had ceased (Gard, 1974;Bryant and Lafferty, 1980). Currentexploitation of phosphorus near thecalving lagoon of Magdalena Bay insouthern Baja California may because for concern (Cordoba, 1981).Because of the scarcity of suitableisolated calving and nursery areas forgray whales, and the whales' specializ­ed feeding habits, future coastal orshallow-water development must bewell monitored to determine any ef­fects on any critical stages of thiswhales' life cycle. For these reasons,habitat protection of the coastal en-

46(4),1984 13

R. V. Miller. 1982. Bowhead whale studies,Autumn 1980-Spring 1981: Harvest,biology and distribution. Rep. Int. WhalingComm. 32:357-370.

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