The , physalus

SALLY A. MIZROCH, DALE W. RICE, and JEFFREY M. BREIWICK

Introduction generally feed on swarms of small thought to be reproductively isolated or , which are cap­ from one another, as their migration The , Balaenoptera tured in their as water is schedules are 6 months out of phase. physalus (Linnaeus, 1758), is the sec­ filtered through. Fin do not A chart of the general distribution is ond largest of the whales in the family exhibit as well defined a social or given in Figure 1. Balaenopteridae, second only to the school structure as do toothed whales, From observations made in the , B. musculus. Fin whales and are usually found solitary or in feeding areas during the range in length up to 27 m (88 feet) small groups (Tomilin, 1957). austral summer, it appears that there (Mackintosh, 1942), and are generally is a progression of arrivals by species, Distribution and Migration gray above and white below. Like all with fin whales arriving on the feeding balaenopterids, they have fringed The general migratory pattern of grounds after the blue whales, but baleen plates instead of teeth, and fin whales, like most balaenopterids, before the sei whales, B. borealis. is a movement between poleward Within the fin whale population, The authors are with the National Marine feeding areas in the summer months migration differs by sexual class, with Laboratory, Northwest and and lower latitudes in the winter pregnant females arriving early and Fisheries Center, National Marine Fisheries Ser­ vice, NOAA, 7fiXJ Sand Point Way N.E., Bin months. Northern and Southern leaving early (Mackintosh, 1965). CI5700, Seattle, WA 98115. Hemisphere fin whale stocks are There is some evidence that immature

Figure I. - Geographic distribution of the fin whale. Simple hatching indicates the summer feeding grounds. Stippling indicates distribution during autumn, winter, and spring; records are scarce during these , and the distribution is to a large extent speculative.

20 Marine Fisheries Review whales do not migrate into as high a unit, Fujino (1960) describes several these stocks. For example, no whales latitude as do the older whales fin whale subpopulations in this marked off north have been (Mackintosh, 1965). region. According to histological and captured off (IWC, 1983). Catch statistics indicate that in the marking experiments, he has found However, no electrophoretic (or Antarctic, and presumably in the an eastern and western group that other) studies have yet been presented as well (Ceta­ may intermingle around the Aleutian that would indicate whether these cean and Turtle Assessment Pro­ Islands, as well as an isolated stock in stocks show genetic differences (Ar­ gram1), fin whales are distributed the East . Fujino also sur­ nason, 1981). In addition, Schmidly over a wider range of latitudes than mises, based on marking studies, that (1981) speculates that there may be an either the blue or sei whales. Fin the stock off may be isolated stock in the northern Gulf of whales can be found from the ice edge isolated as well. Mark recoveries in­ . in Arctic and Antarctic waters to dicate, however, that the that lower latitudes of around 20° Nand S winter off southern range (Jonsgllrd, 1966a; Mackintosh, 1966; from central California to the Gulf of The Antarctic has been divided by Leatherwood et al., 1982). Alaska in summer, and an isolated the IWC into six (formerly five) Because their migrations are con­ population may be resident in the statistical areas. They are based (to ducted in the open rather than . There may well be some degree) on , along coastlines, it is difficult to track other subgroups, but there has been Megaptera novaeangliae, breeding fin whales from summer feeding areas little research directed to this ques­ and feeding concentrations (Mackin­ back to their winter grounds. Conse­ tion. tosh, 1942; 1966), but these areas also quently, we have scant knowledge of apply somewhat to fin whale popula­ tions (Brown, 1962). Since the An­ the location of winter breeding North Atlantic grounds. tarctic harvests (and hence most The International Com­ research) occurred on feeding grounds Stock Identity mISSIOn recognizes the following rather than breeding grounds, catch Because hunting occurs in feeding stocks in the North Atlantic: North and mark-recapture data (Brown, rather than breeding areas, the stocks Norway, West Norway and Faroe 1962) tell us only of dispersal while described herein refer to feeding ag­ Islands, Spain - Portugal- British feeding. Evidence indicates that fin gregations rather than breeding Isles, East - Iceland, West (and blue) whales disperse more than groups. There is a chance that whales Greenland, - Labra­ humpback whales while feeding; con­ that summer on different feeding dor, and . There is no sequently, different breeding groups grounds intermingle on the same evidence that indicates mixing among are likely to overlap in the various breeding grounds. However, given the history of exploitation in the North Atlantic (e.g., where the industry moved from area to area after suc­ cessively overharvesting what ap­ peared to be localized populations), there are indications that there is some separation between the stocks found on di fferent feeding grounds (Mackintosh, 1965; Jonsgllrd, I966b; Mitchell, 1974; Gaskin, 1982; Tl1ln­ nessen and Johnsen, 1982). North Pacific Although the International Whal­ ing Commission (IWC) considers the North Pacific as one management

ICetacean and Turtle Assessment Program. 1982. A characterization of marine and turtles in the middle and North Atlantic areas of the U.S. outer continental shelf. Un­ ~...-/- - - pub!. manuscr.. 450 p. plus appendices. Graduate School of Oceanography, Univ. R.I.. -&&t$U-- "' ~ Kingston. RI 02881. (Prep. for U.S. Dep. [nter. Bur. Land Manage. under Contracr AA551­ A fin whale, surfacing in the North Atlantic off Spain, reveals its prominent CT8-48.) which gives the species its name. Photo by S. Mizroch.

46(4),1984 21 of age (Lockyer, 1972). Mature females bear a calf every 2 or 3 years. Natural Mortality Important natural mortality factors are unknown. The fin whale is relatively free of ectoparasites. Except for worms, Crassicauda sp., the few endoparasitic helminths that infest the fin whale usually appear to be nonpathogenic. on adult fin whales by killer whales, Orcinus orca, is rare but may occur more often in younger animals. Natural mortality rates are difficult to estimate, but appear to be about 4 percent/year in adults and perhaps Head of a fin whale (lower jaw uppermost). The characteristic white plates on somewhat greater in immature the front half of the right baleen plate row are clearly visible. Source: Historical animals (Allen, 1980). Photography Collection, University of Libraries. Exploitation and Population Size History of Exploitation areas (Mackintosh, 1942, 1966; Kawamura, 1982). Since fin whales, like most other Brown, 1962). Breeding areas have In the autumn, fin whales migrate balaenopterids, are fast swimmers not yet been identified, so it is not several thousand miles toward and sink when killed, they were dif­ clear how closely the statistical areas equatorial waters. They fast almost ficult for most to catch, until relate to breeding groups. For completely for several months during modern whaling techniques using the management purposes, however, the the winter, living off their fat stores. explosive and the steam IWC considers each statistical area to powered catcher boat were introduced Reproduction represent one stock unit. in Norway in 1864. However, the The reproductive strategy of fin Japanese perfected a technique in the Life History and Ecology whales is closely integrated and syn­ mid-17th century in which whales Feeding chronized with their annual feeding were netted, attached to a float, and cycle. Their basic reproductive cycle is then hauled to shore for processing. During the summer, most fin biennial, consisting of mating during With this method they were able to whales inhabit high latitudes and the the winter, of the large single catch a number of fin and sei whales, cold eastern boundary currents where precocial calf about a year later on the but on a much smaller scale than food production is high. They range winter grounds, and weaning of the possible with modern techniques mostly offshore and tend to be calf before the end of the following (Tj1lnnessen and Johnsen, 1982). nomadic. They feed primarily on summer on the feeding grounds North Pacific species of euphausiids, or , that (Mackintosh and Wheeler, 1929; congregate in dense shoals near the Laws, 1961). Although small numbers of fin surface-notably superba Conception occurs over a 5-month whales were taken by the Japanese in the Antarctic; E. pacifica, Thy­ period during the winter. Females are from around the middle of the 17th sanoessa inermis, T. longipes, T. spin­ usually monestrous, but if they fail to century, large numbers were taken ifera in the North Pacific; and Mega­ conceive, they may, in rare cases, only after modern whaling was intro­ norvegica and T. inermis ovulate two or three times during one duced to at the start of the 20th in the North Atlantic (Nemoto, 1959). estrous cycle. A postpartum estrus is century. Catches of fin whales off In the Northern Hemisphere, fin very rare. Mean length at birth is Japan peaked at 1,040 in 1914, and whales often supplement their diet about 6 m (20 feet). Calves are wean­ then continued at levels ranging from with small schooling such as ed at an age of 7-11 months (Mackin­ 300 to 400/year until World War II. , Mallotus villosus; anchovies, tosh and Wheeler, 1929; Best, 1966) After World War II, catches began to mordax; and , when they have attained a mean body decline, and ended entirely in 1975 harengus, and may even feed length of about 12 m (40 feet). Both when the IWC prohibited the capture exclusively on fish in some areas male and female fin whales attain sex­ of fin whales in that area. (Jonsggrd, 1966b; Mitchell, 1975; ual maturity between 5 and 15 years Annual catches in the North Pacific

22 Marine Fisheries Review Ocean and ranged from 1,000 to 1,500 from the mid-1950's to 40000 the mid-1960's, after which they de­ clined sharply and ended entirely in 1976, when catches were prohibited. 30000 Catches of fin whales off the west "...... ·/l_fin coast of occurred blue- i i ~,.i \ mostly around California, British Co­ 20000 lumbia, and Alaska. Until 1955, most 1\..../ \/\ whaling occurred off British Colum­

bia, after which catches off California /./.\ ! j "- 10000 . \ began to increase. All fin whale cat­ .\ 1 \ 1 .J\ \_sei ches off the west coast of North /. ,,/I iv'.I ...... i \ \ \ .. America had stopped by 1972. ..' ...... "'" -_ ~...... O. +----...:c;...... ;_-~~.,...-'.-'---"=.,....-...... c'--_r_--'>o.--_r_-....:...__'__, North Atlantic 1920 1930 1940 1960 1970 1980 Modern whaling began off nor­ thern Norway in the late 1860's and spread to Iceland, the , Figure 2.-Catch of fin, sei, and blue whales in the Antarctic, 1920-75 (from Newfoundland, Svalbard (Spits­ the Bureau of International Whaling Statistics). bergen), and islands off the British coasts. In the three northernmost areas and the Hebrides, the initial target species was the blue whale, but tory ship. While blue whale catches Southern Hemisphere declined in the late 1930's, fin whale as blue whale stocks were locally de­ Estimates of current and pre­ catches rose to over 28,000 in 1937 pleted, fin whale catches began to in­ exploitation population sizes of fin (Fig. 2). As the whaling industry crease. In the other areas, fin whales whales by IWC statistical area in the developed again after World War II, dominated from the start. Annual fin Antarctic (Table 2) are from Chap­ fin whale catches rose and averaged whale catches fluctuated from around man (1976) and the Report of the around 25,000/year from 1953 to 300 to 1,300 from 1910 to 1970. By IWC Scientific Committee (lWC, 1961. By 1962, catches began to then, most catches came from Ice­ 1979). land, Newfoundland, and . decline and the industry began con­ In 1921, fin and sperm, Physeter centrating on the . By 1974, less than 1,000 fin whales were macrocephalus, whaling began off the Table 1.-Pre..,xplo~ationand current population sizes of coast of Spain and Portugal. caught, and by 1976 the IWC had fin whales in the northeast Atlantic, However, early catches were excessive prohibited the capture of fin whales in Population estimate the Southern Hemisphere. in this region, and by 1927 local Area Pre-exploitation Current stocks had been depleted to a point of North Norway Several commercial . In the 1950's, Current and Pre-exploitation thousand Stock Sizes fin whaling resumed off northwestern and Spain. By 1973, catches off the Cana­ North Pacific Faroe Islands >2,700 Low hundreds dian coasts had stopped, and cur­ Spain, Portugal, and rently fin whales are taken only off The North Pacific fin whale Scottish Islands >:5,000 east and west Greenland, Iceland, and population is estimated to have rang­ Strait 1,791·11,584 Spain. ed from 42,000-45,000 before whaling began to 14,620-18,630 currently Southern Hemisphere (Ohsumi and Wada, 1974). Modern whaling in the Southern Table 2.-Estimates of pre-exploitation and current fin North Atlantic whale population sizes by Iwe statistical area in the Hemisphere began in 1904, targetting Antarctic. initially on the humpback whale. By Rorvik and J onsg~rd (1981) Population estimate

1913, however, catches of blue and presented rough estimates of pre­ Area Pre-exploitation Current fin whales had overtaken humpback exploitation and current population I (00'-119"W) 12,000 3,100 whale catches. Annual catches of fin sizes of fin whales in the northeast II (O'-59"W) 124,000 19,400 whales ranged from around 2,000 to Atlantic (Table 1). Mitchell (1974) III (O'-69'E) 152,000 38,800 IV (70'-129'E) 60,000 8,400 5,000 from 1911 through 1924, but in­ presents some estimates of current V (130'E-170"W) 28,000 3,100 creased substantially after 1925 due to stock sizes in the northwest Atlantic, VI (120'-169'W) 24,000 12,400 the introduction of the floating fac- ranging from around 3,590 to 6,300. Total 400,000 85,200

46(4),1984 23 Management dian east coast stocks, the Icelandic age of southern fin whales. Discovery Rep. stock, the west Greenland stock, and 31 :327-486. Fin whales are currently taken only Leatherwood, S., R. R. Reeves, W. F. Perrin, Spain-Portugal-British Isles stock. A and W. E. Evans. 1982. Whales, , in the North Atlantic. A small major problem, addressed by several and of the eastern North Pacific aboriginal take is allowed in east ;'esearchers, is the degree of intermin­ and adjacent Arctic waters: Guide to their Greenland, and the IWC has also set identification. U.S. Dep. Commer., NOAA gling between the various North Tech. Rep. NMFS Circ. 444, 245 p. a quota for the west Greenland and Atlantic stocks. Indeed, the question Lockyer, C. 1972. The age at sexual maturity of Spain-Portugal-British Isles stocks. the (Balaenoplera is open as to whether or not there is physalus) using annual layer counts in the ear Research on stock estimation and just one biological stock which occurs plug. J. Cons. Int. Explor. Mer biological parameters has continued as a patchy continuum. 34(2):276-294. on these and other North Atlantic Mackintosh, N. A. 1942. The southern stocks of whalebone whales. Discovery Rep. stocks such as the Canadian east coast Literature Cited 22: 197-300. stock, which supported a fishery from ____. 1965. The stocks of whales. Fish. Allen, K. R. 1980. Conservation and manage­ News (Books) Ltd., Lond., 232 p. 1965 to 1972. ment of whales. Unjv. Wash. Press, Seattle, __---,-,-_. 1966. The distribution of south­ Stocks of fin whales in the 110 p. ern blue and fin whales. In K. S. Norris Southern Hemisphere and the North Amason, U. 1981. Fin whales in the NE Atlan­ (editor), Whales, dolphins, and porpoises, p. tic; relationships between abundance and 125-144. Univ. Calif. Press, Berkeley. Pacific were classified as protected distribution. Holarct. Ecol. 4:245-251. _,---__, and J. F. G. Wheeler. 1929. stocks in the mid-1970's. Additional Best, P. B. 1966. A case for prolonged lactation Southern blue and fin whales. Discovery Rep. information on these stocks has come in the fin whale. Nor. Hvalfangst-Tid. 1:257-540. 55(6): 118-122. Mitchell, E. 1974. Present status of northwest mainly from sightings. Brown, S. G. 1%2. The movements of fin and Atlantic fin and other whale stocks. In W. E. In the Southern Hemisphere and blue whales within the Antarctic zone. Schevill (editor), The whale problem; a status Discovery Rep. 33: 1-54. report, p. 108-169. Harvard Univ. Press, North Pacific, fin whale stocks were Chapman, D. G. 1976. Estimates of stocks Cambridge, Mass. well below estimated pre-exploitation (original, current, MSY level and MSY) (in ____. 1975. Trophic relationships and levels at the time fin whaling ceased. thousands) as revised at Scientific Committee for food in northwest Atlantic meeting June 1975. Rep. Int. Whaling whales. Can. Soc. Zool., Meet., Proc. Can. Recovery data for these stocks has Comm. 26:44-53. Soc. Zool. Annu. Meet. 1974:123-133. been scarce since whaling ceased in Fujino, K. 1960. Immunogenetic and marking Nemoto, T. 1959. Food of baleen whales with the mid-1970's. What little sighting in­ approaches to identifying sub-populations of reference to whale movements. Sci. Rep. the North Pacific whales. Sci. Rep. Whales Whales Res. Inst., Tokyo 14: 149-290. formation is available has been dif­ Res. Inst., Tokyo 15:84-142. Ohsumi, S., and S. Wada. 1974. Status of whale ficult to interpret. These stocks prob­ Gaskin, D. E. 1982. The ecology of whales and stocks in the North Pacific, 1972. Rep. Int. dolphins. Heinemann Educ. Books Ltd., Whaling Cornm. 24:114-126. ably remain at much less than half Lond., Exeter, N.H., 459 p. Rj1lrvik, C. J., and A. Jonsg~rd. 1981. Review their pre-exploitation levels. IWC. 1979. Annex G. Report of the Subcom­ of balaenopterids in the North Atlantic In the North Atlantic, pre­ mittee on Protected Stocks. Append. I. Rep. Ocean. In Mammals in the , Vol. 3, Int. Whaling Comm. 29:84-86. general papers and large cetaceans, p. exploitation levels of fin whale stocks ____. 1983. Annex F. Report of the 269-286. Food Agric. Organ. U.N., Rome, are poorly known. Most of the stocks Subcommittee on Other Baleen Whales. Rep. FAO Fish. Ser. 5. experienced episodic catch histories, Int. Whaling Comm. 33: 123-141. Schmidly, D. J. 1981. Marine mammals of the Jonsg~rd, A. 1966a. The distribution of Balaen­ southeastern coast and the Gulf and only during the last 20 years have opteridae in the North . In K. of Mexico. U.S. Fish Wildl. Serv., BioI. Servo the catch histories been well S. Norris (editor), Whales, dolphins, and por­ Program FWS/OBS-80/41, 163 p. poises, p. 114-124. Univ. Calif. Press, Tomilin, A. G. 1957. Zveri SSSR i prilezhash­ documented and the biological and Berkeley. chikh stran (Mammals of the U.S.S.R. and catch-effort data necessary for stock ___-,,--. I966b. Biology of the North At­ adjacent countries). Volume 9. Kitoobraznye size estimation collected. Current lantic fin whale Balaenoplera physalus (L.) (). Izd. Akad. Nauk SSSR, Moscow, , distribution, migration, and 756 p. [In Russ., Transl. by the Isr. Program stock size estimates are available for food. Hvalradets Skr. 49: 1-62. Sci. Transl., 1%7,717 p.] Avail. U.S. Dep. most of these stocks, although few of Kawamura, A. 1982. Food habits and prey dis­ Commer., Natl. Tech. Inf. Serv., Springfield, them are very reliable. Current tributions of three species in the Va., as TT65-50086. North Pacific Ocean. Sci. Rep. Whales Res. Tj1lnnessen, J. N., and A. O. Johnsen. 1982. research has concentrated on stock Inst., Tokyo 34:59-91. The history of modern whaling. Ulliv. Calif. estimation and biology of the Cana- Laws, R. M. 1%1. Reproduction, growth, and Press, Berkeley, 798 p.

24 Marine Fisheries Review