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 27/09/2021 05:17:25

Link to Item http://hdl.handle.net/1834/26411 The , Pygmy Blue Whale, and the Antarctic or True Blue Whale Introduction in the mid latitude waters of the south- within this ocean basin (Ohsumi and ern Indian Ocean and north of the Ant- Wada, 1974; Mizroch et al., 1984a; The Northern Hemisphere blue arctic Convergence is the smallest Barlow et al., 1994b; Braham3; Gilpatrick whale, musculus muscu- (Ichihara, 1966; Omura et al., 1970; Kato et al.66). One such tentative stock desig- lus Linnaeus 1758; the pygmy blue et al., 1995; Gilpatrick et al.66). Distin- nation is for blue whales occuring dur- whale, Balaenoptera musculus brevi- guishing between the subspecies is dif- ing winter off Baja California and in the cauda Ichihara 1966; and the true blue ficult at sea and, therefore, information Gulf of California (Fig. 4). Photo-iden- whale65 , Balaenoptera musculus inter- on population size and distribution for tification studies have shown that indi- media Burmeister 1871, are members each subspecies may be unreliable. viduals from these concentrations travel of the Balaenopteridae family whose in summer and fall to waters off Cali- Distribution and Migration subspecies contain the largest fornia (Calambokidis et al.,1990; ever known to have lived on Earth Blue whale distribution is worldwide Barlow et al.,1997; Sears et al.67). Pre- (Rice12). Adult blue whales can attain (Fig. 24). Presumably they follow a liminary studies of these California/ lengths of about 30 m and weigh up to migration pattern of seasonal north- Mexico whales, based on body-length 160 t in the Southern Oceans (Mackin- south movements between summering data from whaling records and aerial tosh, 1942). In the North Atlantic and and wintering areas, but some evidence photogrammetry, indicate that they are North Pacific, their maximum lengths suggests that individuals in certain ar- morphologically distinct from blue have been recorded at 27 m (True, 1904) eas remain in low latitudes year-round whales of the western and central North and 26.8 m (Reeves et al., 1985), respec- (Donovan, 1984; Yochem and Leather- Pacific (Gilpatrick et al.66). tively. They are gray in color (appear- wood, 1985; Reilly and Thayer, 1990). Acoustic monitoring has resulted in ing blue below the water surface) with The location of wintering areas is still blue whale vocalizations being recorded distinct gray and white mottling, while somewhat speculative (Jonsgård, 1966; off Oahu, Hawaii, and the Midway Is- their ventral surface is lighter in color. Mackintosh, 1966), whereas known lands (Northrop et al., 1971; Thompson Their dorsal fin is relatively small (Fig. summer feeding areas are in the rela- and Friedl, 1982), although sightings or 23). Like other balaenopterids, they tively high latitudes. Migratory routes are strandings in Hawaiian waters have not have fringed baleen plates instead of teeth not well known, mainly because blue been reported. Nishiwaki (1966) noted and ventral grooves which allow for the whales occur primarily in the open ocean. the occurrence of blue whales near the filtering of large quantities of water dur- Aleutian Islands and in the Gulf of North Pacific ing feeding on swarms of euphausiids. Alaska. However, as of 1987, there have Rice12 recognizes the B. musculus Blue whales are found along the been no blue whale sightings in these subspecies based on body size and geo- coastal shelves of North America and waters (Leatherwood et al., 1982; Stewart graphic distribution. B. m. intermedia, South America in the Pacific Ocean et al., 1987; Forney and Brownell68). No which occurs in the high latitudes of the (Rice, 1974; Clarke, 1980; Donovan, distributional information exists for the Southern Oceans, is the largest (maxi- 1984). The IWC Scientific Committee western North Pacific Ocean. mum length = 30 m), B. m. musculus of recognized one blue whale stock in the 67 Sears, R., M. Berube, and D. Gendron. 1987. the Northern Hemisphere is slightly North Pacific (Donovan, 1991). How- A preliminary look at the distribution and mi- smaller (maximum length = 27 m), and ever, there is increasing evidence sug- gration of blue whales (Balaenoptera musculus) B. m. brevicauda (pygmy blue whale) gesting that more than one stock exists in the northeast Pacific, based on the photo-iden- tification of individuals (Abstr.). In Proceedings of the Seventh Biennial Conference on the Biol- 65 B. m. intermedia is referred to in the literature 66 Gilpatrick, J. W., W. L. Perryman, and R. L. ogy of Marine , 1987, Miami, Fla. by three common names: Antarctic blue whale, Brownell. 1997. Geographic variation in North 68 Forney, K. A., and R. L. Brownell. 1996. Pre- southern ordinary blue whale, and the true blue Pacific and Southern Hemisphere blue whales liminary report of the 1994 Aleutian Island ma- whale. To avoid confusion, this review refers to (Balaenoptera musculus). Unpubl. doc. SC/49/ rine survey. Unpubl. doc. SC/48/011, this subspecies as the “true” blue whale. 09, 33 p., submitted to Rep. Int. Whal. Comm. 15 p., submitted to Rep. Int. Whal. Comm.

38 Marine Fisheries Review Figure 23.—A blue whale surfacing. Note the mottled coloration and very small dorsal fin. J. M. Waite, NMML Collection.

Figure 24.—Worldwide distribution of all blue whale species. Adapted from Mizroch et al. (1984a).

The Costa Rica Dome (centered presence: 1) the standing stock of prey utilize the area. Blue whales have been roughly around lat. 9°N, long. 89°W) (i.e. euphausiids) that results from this sighted in the Dome area in all seasons, is a stationary eddy in the eastern tropi- highly productive area, 2) the aggrega- but there is a peak in occurrence from cal Pacific Ocean which appears to be tion of juvenile, nonmigratory whales, June through November. an important year-round habitat for blue 3) the occurrence of a resident stock of North Atlantic whales (Fig. 13) (Reilly and Thayer, Northern Hemisphere blue whales, or 1990). Reilly and Thayer (1990) sug- 4) temporal overlap, when both North- Blue whales are found from the Arc- gested four reasons for this year-round ern and Southern Hemisphere whales tic to at least the mid latitude waters of

61(1), 1999 39 the North Atlantic with occasional oc- Sightings have been reported from the for these areas. Off the coast of Oregon currences in U.S. Exclusive Economic Gulf of Aden, Persian Gulf, Arabian and Washington, no blue whales were Zone (EEZ)69 waters (Yochem and Sea, and across the Bay of Bengal to sighted during an aerial survey in 1991 Leatherwood, 1985; Wenzel et al., 1988; Burma and the Strait of Malacca (Fig. (Green et al.75) or during ship-based line CeTAP70; Gagnon and Clark71). These 12, 14) (Mizroch et al., 1984a). The transect surveys in 1996 (Barlow74). In whales are currently recognized as one migratory movements of these whales the eastern tropical Pacific, Wade and stock by the IWC (Donovan, 1991). are unknown. Gerrodette (1993) estimated 1,415 (CV Sightings of blue whales occur most = 0.243) blue whales from ship-based Southern Hemisphere frequently off eastern Canada. During line transect survey data. There are no winter, they are found in the waters off Blue whales in the Southern Hemi- statistically reliable population esti- Newfoundland. In summer, they are sphere are assigned to six stock areas mates for the eastern North Pacific north found in Davis Strait (Mansfield, 1985), designated by the IWC (Fig. 9) (Donovan, of the State of Washington or in the in the Gulf of St. Lawrence (from the 1991). These areas are consistent with the western North Pacific. Nonetheless, it north shore of the St. Lawrence River presumed blue whale feeding locations, appears that at a minimum there are estuary to the Strait of Belle Isle), and although reliable distributional informa- currently over 3,300 blue whales in the off eastern Nova Scotia (Fig. 6) (Sears tion on blue whales is still scarce. His- North Pacific (Wade and Gerrodette, et al.67). torical catch records indicate that the 1993; Barlow74). In 1992, the U.S. Navy and its con- true blue whale and the pygmy blue According to calculations based on tractors conducted an extensive acous- whale may be geographically segre- historic whaling data, there were an es- tic survey of the North Atlantic using gated (Kato et al., 1995; Brownell and timated 4,900 (no CV available) blue the Integrated Underwater Surveillance Donahue73). The distribution of the whales inhabiting the North Pacific prior System’s (IUSS) fixed acoustic array pygmy blue whale is north of the Ant- to commercial exploitation (Gambell, (Clark, 1995). This study provided in- arctic Convergence, while that of the 1976). Admittedly, estimates such as formation on the seasonality and geo- true blue whale is south of the Conver- these are rather speculative. graphic distribution of several baleen gence in the austral summer (Fig. 10) whale species’ vocalizations (Clark et (Kato et al., 1995). True blue whales North Atlantic al.72). Localizations of the sounds indi- occur mainly in the relatively high lati- Braham3 provided a population esti- cated concentrations of blue whales on tudes. During summer, the true blue mate for the entire North Atlantic of the Grand Banks off Newfoundland and whale is found close to the ice edge between 100 and 555 blue whales based west of the British Isles. One blue whale (south of lat. 58°S) with concentrations on history of catches and trends in was tracked acoustically for 43 days, dur- between lat. 66Ð70°S and long. 60Ð CPUE22. This estimate is not considered ing which time it traveled 1,400 n.mi in 80°E (Fig. 10) (Kasamatsu et al., 1996). statistically reliable by the IWC. Ongo- an area that included waters northeast of No new information on wintering areas ing photo-identification studies (since Bermuda to the southwest and west of has been reported since Braham’s 1991 1979) in the Gulf of St. Lawrence have Bermuda (Gagnon and Clark71). status review3; therefore, there are no cataloged over 320 individual blue data to validate IWC stock designations whales (Sears et al., 1990). There is Northern Indian Ocean in the Southern Hemisphere. evidence from ship-based surveys Blue whales have been reported year- west and southwest of Iceland that blue Current and Historical Abundance round in the northern Indian Ocean. whale abundance has been steadily North Pacific increasing since the late 1950’s; and from 1979 to 1998 at a rate of 5.2% 69 Gambell (1976) provided a popula- The EEZ of a maritime country includes all wa- (CV = 0.22) per year (Sigurjónsson and ters of the continental shelf, continental slope, and tion estimate for the entire North Pa- Gunnlaugson, 1990). There is no extends roughly 200 n.mi from the coast seaward. cific of 1,600 blue whales (range = 70 statistically reliable estimate of blue CeTAP. 1982. A characterization of marine 1,400Ð1,900; no CV or CI provided) mammals and turtles in the mid and North At- whale abundance in the eastern North lantic areas of the U.S. outer continental shelf. based on history of catches and trends Atlantic. Cetacean and Turtle Assessment Program, Univ. in CPUE22. However, this estimate is R.I. Final rep. #AA551-CT8-48 to Bur. Land Manage., Wash., D.C., 538 p. likely no longer realistic. From ship- 74 71 Gagnon, C. J., and C. W. Clark. 1993. The use based line transect surveys off Califor- Barlow, J. 1997. Table 2. Minutes from the fifth of U.S. Navy IUSS passive sonar to monitor the meeting of the U.S. Pacific Scientific Review nia in 1991Ð93 and off California, Or- Group Meeting, October 1997, La Jolla, CA. movement of blue whales (Abstr.). In Proceed- 74 ings of the Tenth Biennial Conference on the egon, and Washington in 1996, Barlow Available from D. P. DeMaster, Natl. Mar. Mam- Biology of Marine Mammals, 1993, Galveston, estimated 1,927 (CV=0.16) blue whales mal Lab., NMFS, NOAA, 7600 Sand Point Way Tex. N.E., Seattle, WA 98115. 75 72 Clark, C. W., C. J. Gagnon, and D. K. Green, G. A., J. J. Brueggeman, R. A. Mellinger. 1993. Whales ‘93: the application of 73 Brownell, R. L., and M. A. Donahue. 1994. Grotefendt, C. E. Bowlby, M. L. Bonnell, and K. the Navy IUSS for low-frequency marine mam- Southern Hemisphere pelagic whaling for pygmy C. Balcomb. 1992. Cetacean distribution and mal research (Abstr.). In Proceedings of the Tenth blue whales: review of catch statistics. Unpubl. abundance off Oregon and Washington, 1989Ð Biennial Conference on the Biology of Marine doc. SC/46/SH6 submitted to Rep. Int. Whal. 1990. Final rep. to Minerals Manage. Serv., Mammals, 1993, Galveston, Tex. Comm., 9 p. Contr. 14-12-0001-30426, completed May 1992.

40 Marine Fisheries Review Figure 25.—Partly flensed blue whale awaiting further processing at an Alaska whaling station. University of Washington Special Collections, Lagen Collection, negative UW18185.

Based on whaling records, Gambell = 150,000Ð210,000) true blue whales try shifted its effort away from declining (1976) estimated that from 1,100 to in the Southern Hemisphere (Gambell, blue whale stocks to other large whale 1,500 blue whales occured in the entire 1976). Based on a comparison of cur- species and then resumed hunting blue North Atlantic prior to commercial exploi- rent and historic estimates, some re- whales when they appeared more abun- tation (Gambell, 1976), although accord- searchers noted that southern blue dant. The result was a cyclical rise and ing to the IWC’s Scientific Committee this whale stocks do not appear to be recov- fall, leading to severe depletion of blue estimate is statistically unreliable. ering from exploitation (Table 4) (Hat- whale stocks worldwide (Mizroch et al.49). anaka and Komatsu76). Northern Indian Ocean North Pacific In the mid 1970’s, the southern In- There are no estimates of current or dian Ocean’s pygmy blue whale popu- From 1889 until 1965, approximately historic abundance for this blue whale lation was estimated at 5,000 individu- 5,761 blue whales were taken from the stock. als (no CV available) (Gambell, 1976). North Pacific (Braham3). Evidence of An estimated 10,000 (no CV available) a population decline can be seen in Japa- Southern Hemisphere pygmy blue whales inhabited this ocean nese catch data. In 1912, 236 blue Since 1965, there have been only historically (Gambell, 1976). whales were caught, and from 1913 to seven sightings of true blue whale 1965, the catch numbers declined con- calves in waters south of lat. 60°S Historic Exploitation Patterns tinuously (Fig. 25) (Mizroch et al., (Braham3) despite IWC/IDCR surveys In 1864, explosive harpoons and steam- 1984a). Since the IWC banned commer- in these areas. The Scientific Commit- powered catcher boats were introduced in cial whaling in the North Pacific in tee agreed that, while a reliable estimate Norway, allowing the exploitation of blue, 1966, no blue whales have been re- of abundance of Southern Hemisphere fin, and sei whales, which are generally ported taken from those waters. blue whales could not be developed larger and faster than previously exploited North Atlantic because data on these stocks were in- humpback and right whales. Whalers in complete, there were more than 500 the North Pacific and Antarctic soon By 1882, Norway’s whaling opera- blue whales in the Southern Oceans added this modern equipment to their ar- tions, which had originally focused on blue (IWC, 1990). More recently, the IWC senal. As this new technology spread and whales, began to take more fin whales due calculated an abundance estimate of began to receive widespread use, blue to the scarcity of the former (Mizroch et al., 1,255 blue whales (no CV available) by whale populations began declining world- 1984a). The search for blue whales ex- combining data from IWC/IDCR and wide. Subsequently, the whaling indus- panded to include waters off Iceland, the Japanese Sighting Vessel (JSV) surveys Faeroe Islands, Newfoundland, Svalbard from 1978 to 1988 (IWC, 1996a). 76 Hatanaka, H., and M. Komatsu. 1993. Inter- (Spitsbergen), and the islands off the Brit- Prior to the start of Antarctic com- national action plan for recovery of large ish coast (Fig. 6, 7, 18). whales—towards recovery of blue whales. mercial exploitation in the early 1900’s, Unpubl. doc. SC/45/SHBa27 submitted to Rep. From the early 1880’s through 1915, there were an estimated 180,000 (range Int. Whal. Comm., 3 p. there were 6,000 blue whales taken

61(1), 1999 41 from land-based stations in Iceland to the misidentification of pygmy blue especially with a focus on ecosystem re- (Sigurjónnson and Gunnlaugsson, whales in the original data and is a pos- quirements of baleen whales (Kawamura, 1990). In 1915, the Icelandic Parliament sible problem in the interpretation of 1994; Clapham and Brownell, 1996). prohibited all land-based whaling due catch data from other countries as well. to the apparent depletion of blue and Reproduction humpback whales. By 1935, whaling Current Exploitation Both male and female blue whales had resumed from one land-based sta- The current catch limit imposed by reach sexual maturity at 5Ð15 years of tion in western Iceland and continued for age. Females give birth to a single 7Ð8 the IWC is zero for all blue whale stocks 5 years, a period in which 30 blue whales m calf every 2 or 3 years after a gesta- (IWC, 1995b). were taken. By 1952, fewer than 15 blue tion period of approximately 12 months whales were taken per year by all Icelan- Life History and Ecology (Mizroch et al., 1984a). Calves are dic whalers (Mizroch et al., 1984a). The weaned late the following summer at Feeding IWC provided complete protection to the around 7 months and at a length of about blue whale in the North Atlantic in 1955, Blue whale distribution is likely 16 m (Mizroch et al., 1984a; Anony- but whaling continued off the coasts of linked to nutritional requirements mous, 1994a). However, it must be Iceland until 1960. From the close of (Reilly and Thayer, 1990; Schoenherr, noted that these reproductive param- World War II to 1960, 163 blue whales 1991; Kawamura, 1994). Areas of cold, eters are not current, because the IWC were taken off Iceland (Sigurjónsson and upwelling currents (i.e. eastern sides of has gathered little new information Gunnlaugsson,1990). Since 1985, there the oceans) provide large quantities of since 1967 (Mizroch et al., 1984a). have been no reported takes of blue euphausiid crustaceans (krill) which is Natural Mortality whales in the North Atlantic. a primary prey item of blue whales. Areas of dense prey aggregations may Nothing is known of natural mortal- Southern Hemisphere be seasonal, year-round, or strongly in- ity in blue whales. They appear to be A total of 330,684 blue whales (all fluenced by the occurrence of El Niño relatively free of ecto- and endopara- subspecies) were taken in the Southern Southern Oscillation (ENSO) events sites (Rice, 1978b). Lampreys are found Hemisphere between 1909 and 1967 (Reilly and Thayer, 1990; Schoenherr, attached to the dermal surface of large (Braham3). Commercial harvest of blue 1991; Gendron and Sears, 1993). The whales in warmer waters. The killer whales amounted to a take of approxi- krill species on which these whales rely whale, Orcinus orca, may prey on blue mately 2,000Ð6,000 whales per year include: Euphausia pacifica, Thysanoessa whales, but, this may be rare. It is pos- from 1914 to 1924 in this region. But inermis, T. longipes, and T. spinifera sible that immature or weakened ani- when factory whaling ships were intro- (Schoenherr, 1991) in the North Pacific; mals may become targets for killer duced in the late 1920’s, the take in- Meganyctiphanes norvegica and T. whales under certain conditions (Tarpy, creased to 12,734 in the 1928Ð29 sea- inermis in the North Atlantic; and E. 1979). Natural mortality rates are un- son and to 29,410 in the 1930Ð31 sea- superba (Kawamura, 1994), E. crystal- known, but they are likely to be similar son (Mizroch et al., 1984a). These ships lorophias, and E. vallentini in the Ant- to those of the fin whale—about 4% per allowed more efficient processing of arctic (Nemoto, 1959). Off the Pacific year in adult whales (Allen, 1980). whales at sea and led to the rapid de- coast of Baja California, blue whales cline of blue whale stocks in the South- have been reported to feed on concen- Human-related Mortality ern Hemisphere. By 1938 the number trations of the pelagic red crab, Pleuro- Fisheries Interactions of fin whales being caught was more ncodes planipes (Rice, 1978b). How- than twice the number of blue whales ever, blue whales have been observed There are no reports of fisheries-re- caught (14,923) in the Southern Hemi- between February and April within the lated mortality or serious injury in any sphere during the previous three decades Gulf of California feeding on surface of the blue whale stocks. However, (Mizroch et al., 1984a). Commercial hunt- swarms of Nyctiphanes simplex, a eu- Barlow et al. (1997) noted that a con- ing of blue whales in the Southern Oceans phausiid species (Sears, 1990; Gendron flict may exist in the offshore drift was banned by the IWC in 1967. and Sears, 1993). Sears (1990) regarded gillnet fishery in the North Pacific (i.e. The recent release of withheld Soviet the latter species as the principal prey off California). Blue whale interactions whaling records shows a discrepancy in of blue whales in the region. with fisheries may go undetected be- the number of true blue whales origi- Some researchers have speculated cause the whales are not observed after nally reported caught by the U.S.S.R. that a critical factor influencing blue they swim away while carrying fishing in southern waters between 1947 and whale recovery in the Southern Hemi- gear. Fishermen report that large blue and 1980 (Zemsky et al., 1995). Originally, sphere may be interspecific competition fin whales usually swim through the nets a take of 3,651 true blue whales was with minke and nonwhale krill predators without entangling and with very little reported to the IWC for this period, but (Fraser et al., 1992). However, no con- damage to the net (Barlow et al., 1997). the recently revealed data show that clusions can be made about this type of In U.S. North Atlantic waters, the total only 3,462 true blue whales were taken competition until further behavioral and mortality and serious injury from fisher- (IWC, 1995a). This is most likely due distributional information is collected, ies-related incidents is considered insig-

42 Marine Fisheries Review Table 12.—Factors possibly influencing the recovery of blue whales under the ESA (1973)¤4 (a)(1),1992 Amend. (northern Indian Ocean and Southern Hemisphere data are not available).

Factors North Pacific North Atlantic

1. Present or threatened destruction or modifi- Offshore oil and gas development Offshore oil and gas development; noise from vessel traffic cation of habitat

2. Overutilization for commercial, recreational, Whale watching, scientific research, photography, and associated Whale watching, scientific research, photography, and asso- scientific, or educational purposes vessel traffic ciated vessel traffic

3. Disease or predation Unknown Unknown

4. Other natural or man-made factors Vessel collisions; entanglement in fishing gear (e.g. offshore drift Vessel collisions gillnet) nificant, but blue whale/fishery interac- Noise Disturbance more below their maximum sustainable tions have not been thoroughly investi- Studies have shown that blue whales yield (MSY) levels (IWC, 1995b). gated for impacts (Waring et al., 1998). respond to the sound created by ap- The accuracy and availability of abundance estimates and stock identity Vessel Collisions proaching vessels in a variety of ways, depending on the behavior of the ani- has not improved since Braham’s 1991 3 It is possible that mortality from ship mals at the time of approach and on status review , with the exception of the strikes affects all blue whale stocks. speed and direction of the approaching blue whales that occur off California Additional mortality due to vessel vessel. Blue whales involved in feed- and Mexico. The IWC has suggested strikes likely goes unreported because ing react less rapidly and with less ob- long-term acoustic surveys and satellite the bodies of injured or killed animals vious avoidance maneuvers than those tracking in addition to visual survey did not strand or investigations of not involved in feeding (Richardson et methodology to better evaluate the den- stranded animals did not reveal the al., 1995). Within the St. Lawrence sity and distribution of blue whales in the trauma of a ship collision. River estuary, heavy recreational and Southern Hemisphere (IWC, 1996a). In 1980, 1986, 1987, and 1993, ship commercial vessel traffic from several These suggestions are also applicable to strikes have been implicated in the sources (e.g. industrial freight, whale stocks in the Northern Hemisphere. In deaths of blue whales off California watching) may affect summering blue addition, genetic analysis holds prom- (Barlow et al., 1997). In addition, sev- whales. Studies in the St. Lawrence ise for distinguishing between true and eral photographically identified blue River showed the most evident reactions pygmy blue whales in the Southern whales from California waters were to these vessels occurred when boats Hemisphere (IWC, 1996a). observed with large scars on their dor- made fast, erratic approaches or sudden The factors possibly influencing the sal areas that may have been caused by changes in direction or speed (Edds and status of blue whales are summarized ship strikes. In the California/Mexico MacFarlane, 1987; MacFarlane77). in Table 12. A Recovery Plan for blue stock, annual incidental mortality due to Noise disturbance from seismic ex- whales has been prepared by the NMFS ship strikes averaged 0.2 whales during ploration apparently does not affect blue in which measures to protect and moni- 1991Ð95 (Barlow et al., 1997). However, whales in any significant manner. When tor the recovery of this species are iden- the effect that this type of mortality or noise pulses from air guns were pro- tified (Anonymous, 1998). At this time, injury may have on the status of blue duced off Oregon, blue whales in the however, any reevaluation of blue whale whale stocks is currently unknown. area continued vocalizing at the same status awaits the collection of more re- More recently, in March 1998 a ju- rate as before the pulses, suggesting liable information on stock structure, venile male blue whale was reportedly they were undisturbed by the noise distribution and migration patterns, struck and killed by a commercial ves- (McDonald et al., 1993). trends in abundance, causes of mortal- sel and was carried on the bow of the ity, and factors influencing the recov- vessel into Narragansett, R.I. The Classification Status ery of blue whale stocks, as well as the necropsy of this whale indicated that The blue whale was listed as endan- development of objective delisting cri- death occurred as a result of a ship gered under the ESA in 1973 and given teria. Therefore, until such information strike, including bone fractures at sev- protection under the MMPA. All blue is available, the classification status of eral locations along one side of the whale stocks in U.S. waters are listed all blue whale stocks should remain ’s body (Anonymous, 1998). The as endangered (Anonymous, 1994a). unchanged. However, abundance in the 37 PBR level for the western North At- Internationally, all blue whale stocks are California/Mexico region of the eastern lantic blue whale is currently 0.6 whales classified as “Protected Stocks” by the North Pacific may be increasing to ap- per year (Waring et al., 1998). Clearly, IWC. Under this designation, the IWC proximately 30% of its preexploitation if vessel collisions occur frequently, recognizes that these stocks are 10% or levels. If new abundance trend data in- blue whale recovery in U.S. Atlantic dicate that such increases continue, blue waters will be affected. However, the 77 MacFarlane, J. A. F. 1981. Reactions of whales whales in this region may be candidates to boat traffic in the area of the confluence of the frequency of such mortalities is poorly Saguenay and St. Lawrence Rivers, Quebec. for a consideration to downlist from documented. Unpubl. doc., 50 p. endangered to threatened.

61(1), 1999 43