The Great Whales: History and Status of Six Species Listed as Endangered Under the U.S. Endangered Species Act of 1973 Item Type article Authors Perry , Simona L.; DeMaster, Douglas P.; Silber , Gregory K. Download date 24/09/2021 18:11:28 Link to Item http://hdl.handle.net/1834/26411 The Fin Whale Introduction predatory advantage over other balaen- 1994a). Most migrate seasonally from opterids (Tershy and Wiley, 1992). The relatively high-latitude Arctic and Ant- The fin whale, Balaenoptera physalus dorsal fin is generally falcate with a arctic feeding areas in the summer to Linnaeus 1758, is the second largest mem- pointed tip, but it may be quite variable relatively low-latitude breeding and ber of the family Balaenopteridae (after in its shape (Fig. 26). calving areas in winter. Arrival time on the blue whale, B. musculus). Mature The fin whale is usually found alone the summer feeding areas may differ animals range from 20 to 27 m in length, or in small groups, and the species ap- according to sexual class, with pregnant with mature females being approxi- pears to have no well-defined social females arriving earlier in the season mately 1.47 m longer than mature males structure. Like other balaenopterids, than other whales (Mackintosh, 1965). (Aguilar and Lockyer, 1987). All fin they have fringed baleen plates instead The location of winter breeding areas whales have a consistent pattern of of teeth, and ventral grooves which ex- is still uncertain. These whales tend to asymmetrical pigmentation which is pand during feeding and allow the migrate in the open ocean, and therefore particularly recognizable on the head whale to engulf large quantities of wa- migration routes and the location of win- region. The whale’s underside, right lip, ter along with small crustacean and fish tering areas are difficult to determine. and right baleen plate are yellow-white, prey items. while their main body, left lip, and left North Pacific Distribution and Migration baleen plate are a fairly uniform gray- The IWC’s Scientific Committee rec- blue color. This asymmetry may be Fin whales inhabit a wide range of ognized two management stocks in the linked to the whale’s feeding behavior, latitudes between lat. 20–75°N and 20– North Pacific: the East China Sea (Fig. 5) but there is no evidence that their un- 75°S (Fig. 27) (Mackintosh, 1966; and the rest of the North Pacific (Donovan, usual coloration gives them any type of Leatherwood et al., 1982; Anonymous, 1991). One reason for this broad desig- Figure 26.—Two fin whales, one noticeably smaller, surface simultaneously revealing their falcate dorsal fins and dark colora- tion. S. Hill, NMML Collection. 44 Marine Fisheries Review nation is the lack of data on geographic tral California coast, although there is are scarce in summer and winter (Lee, or genetic separation within the species. a seasonal peak during the summer and 1993; Wade and Gerrodette, 1993). Because fin whales tend to inhabit such a autumn (Barlow, 1995; Forney et al., Three stocks have been designated in wide range of latitudes in all seasons, it is 1995; Dohl et al.78). Fin whales have U.S. waters of the North Pacific for hard to predict where individual animals also been found in summer off Oregon stock assessment and management pur- travel during pelagic migrations. (McDonald et al., 1995; Green et al.75) poses: 1) California/Oregon/Washing- Mizroch et al. (1984b) suggested five and in summer and autumn in Shelikof ton, 2) Alaska, and 3) Hawaii (Barlow possible stocks within the North Pacific Strait (north of Kodiak Island, Alaska) et al., 1997; Hill et al., 1997). Around based on histological and tagging ex- and the Gulf of Alaska (Brueggeman et Hawaii, the fin whale is rarely sighted periments (Fig. 4, 5) (Fujino, 1960; al.79). The Gulf of California is inhab- (Shallenberger80; Balcomb81), but Rice, 1974; Tershy et al., 1993): ited year-round by fin whales, with a acoustic recordings off Oahu and Mid- peak in abundance during winter and way Islands suggested a migration into 1) East and West Pacific (intermingling spring (Tershy et al., 1993; Silber et al., Hawaiian (U.S. EEZ) waters in autumn around the Aleutian Islands), 1994). Whether fin whales found off and winter (Thompson and Friedl, 2) East China Sea, southern and central California during 1982). 3) British Columbia, summer migrate to the Gulf of Califor- 4) Southern/Central California to Gulf nia for winter awaits further investiga- North Atlantic of Alaska, and tion (Barlow et al., 1997). In low latitudes In 1976, the IWC identified seven 5) Gulf of California. of the eastern tropical Pacific, fin whales stock areas in the North Atlantic (Donovan, 1991) based on “statistical Discovery tags38 injected and some- 78 Dohl, T. P., R. C. Guess, M. L. Duman, and R. convenience” and history of exploita- C. Helm. 1983. Cetaceans of central and north- times recovered during the era of com- ern California, 1980-83: Status, abundance and tion (Fig. 28): mercial whaling demonstrated possible distribution. Contr. 14-12-0001-29090. Final rep. to Minerals Manage. Serv., 284 p. southern California wintering areas and 80 79 Brueggeman, J., G. A. Green, K. C. Balcomb, C. Shallenberger, E. W. 1981. The status of Ha- summering areas ranging from central E. Bowlby, R. A. Grotefendt, K. T. Briggs, M. L. waiian cetaceans. Rep. MMC-77/23 prep. for Mar. California to the Gulf of Alaska (Rice, Bonnell, R. G. Ford, D. H. Varoujean, D. Heine- Mammal. Comm., Contr. MM7AC/28, 79 p. 1974). Other researchers have more re- mann, and D. G. Chapman. 1990. Oregon-Wash- 81 Balcomb, K. C. 1987. The whales of Hawaii, ington marine mammal and seabird survey: Infor- including all species of marine mammals in Ha- cently found year-round concentrations mation synthesis and hypothesis formulation. Prep. waiian and adjacent waters. Marine Mammal of fin whales off the southern and cen- for U.S. Dep. Inter., OCS Study MMS 89-0030. Fund, San Francisco, Calif., 99 p. Figure 27.—Worldwide fin whale distribution. Adapted from Mizroch et al. (1984b). 61(1), 1999 45 A fin whale breaking the surface. Note the white coloration on the lower lip. S. Kraus, NMML Collection. 1) North Norway, 2) West Norway-Faroe Islands, 3) British Isles-Spain and Portugal, 4) East Greenland-Iceland, 5) West Greenland, 6) Newfoundland-Labrador, and 7) Nova Scotia. In 1991, during the Special Meeting on the Comprehensive Assessment of North Atlantic Fin Whales, the IWC’s Scientific Committee adopted alterna- tive stock boundaries, which relate to historic catch areas and may be useful for assessing population abundance (IWC, 1992b; Butterworth and Punt, 1992). However, these suggested boundaries were not considered repre- sentative of biological stocks by the Scientific Committee (IWC, 1992b). Underwater listening systems (part of the IUSS) have demonstrated that the fin whale is the most acoustically com- mon whale species heard in the North Atlantic (Clark, 1995). They are acous- Figure 28.—North Atlantic fin whale stock boundaries recognized by the IWC tically detected year-round in the Nor- (Donovan, 1991). wegian Sea, and vocalizations show a sea- 46 Marine Fisheries Review sonal shift in which whales move south- whales breed to validate this designa- CPUE22 (Braham3). Waring et al. (1998) ward during autumn and northward dur- tion (IWC, 1992b). considered 1,700 (CV = 0.59) fin ing spring in this region. The IUSS tracked whales to be the minimum population fin whales during seasonal migrations Current and Historical Abundance estimate (Nmin) for an area from the along both the western and eastern Atlan- northern Gulf of Maine to the lower Bay North Pacific tic. The autumn southward migration pat- of Fundy (Nova Scotia stock) based on tern in the western North Atlantic was The most current (1991) population line-transect surveys in July through from Newfoundland-Labrador, past Ber- estimate for the entire North Pacific is September 1991–92. For the British muda, and into the West Indies, while in between 14,620 and 18,630 based on Isles/Spain and Portugal stock, Braham3 the eastern North Atlantic, the pattern was history of catches and trends in CPUE22 provided in 1991 an initial, preex- from the British Isles to the coasts of Spain (Braham3). Prior to exploitation, there ploitation population estimate of 10,500 and Gibraltar (Fig. 6, 7) (Clark, 1995). were an estimated 42,000–45,000 fin (95% C.I. 9,600–11,400) fin whales. In U.S. waters of the North Atlantic, whales in the entire North Pacific the NMFS has recently designated one (Ohsumi and Wada, 1974). In the early Southern Hemisphere stock of fin whale (Waring et al., 1998). 1970’s, this entire North Pacific popu- In the Southern Oceans, the most The fin whale is common from Cape lation had been reduced to between current (1979) population estimate is Hatteras northward (Fig. 6), where the 13,620 and 18,630 fin whales (Ohsumi 85,200 (no CV) fin whales based on the species accounted for 46% of all large and Wada, 1974). history of catches and trends in CPUE22 whales and 24% of all cetaceans sighted The most recent data from 1991, 1993, (IWC, 1979). In addition, 15,178 over the continental shelf between Cape and 1996 line-transect surveys of waters whales (no CV given and uncorrected Hatteras and Nova Scotia during 1978– off California, Washington, and Oregon for probability of sighting) were esti- 82 aerial surveys (Waring et al., 1998). yielded an estimated current population mated to occur within surveyed areas The single most important area for this abundance of 1,236 (CV = 0.20) fin south of lat.