1999 

 OUR LIVING OCEANS 



whales in the western Arctic may occur in both 

 offshore and coastal waters, with concentrations 

 in Cook Inlet, Bristol Bay, Norton Sound, 

 Kasegaluk l.agoon, and the Mackenzie Delta. It is 

 assumed that most beluga whales Irom these sum- 

 mering areas overwinter in the Bering Sea. Sea- 

 sonal distribution is allected by ice cover, tidal 

 conditions, access to prey, temperature, and hu- 

 man interaction. During winter, beluga whales 

 occur in otishore waters associated with pack ice. 

 In the spring, they migrate to warmer coastal es- 

 tuaries, bays, and rivers lor molting and calving. 

 Annual migrations may cover thousands ot kilo- 

 meters. 



Five ptitative stocks of beluga whales are rec- 

 ognized within U.S. waters: Cook Inlet, Bristol 

 Bav, Kastern Bering Sea, Eastern Chukchi Sea, and 

 Beaufort Sea. 



Population Size 



Ihe sources ot information to estimate abun- 

 dance of belugas have included both opportunis- 

 tic and systematic observations. The most recent 

 survey conducted in U)92 tor the Beaufort Sea 

 stock resulted in an estimate of approximately 

 20,803 whales. A correction factor of 2 has been 

 recommended for the Beaufort Sea stock, result- 

 ing in a current population estimate of .V),2'i,S. 

 The estimated minimum size of the Eastern 

 Chukchi stock of belugas is 1 ,200 based on counts 

 of animals from aerial surveys conducted dtiring 

 1989-91. If this count is corrected for the pro- 

 portion of animals that were diving and thus not 

 visible at the surface, and for the proportion ot 

 newborns and vearlings not observed due to small 

 size and dark coloration, the total corrected esti- 

 mate for the Eastern Chukchi Sea is 3,710. The 

 1994 population estimate for Bristol Bay was 

 1,555. For Cook Inlet, the 1997 population esti- 

 mate was 834 (N = 7 12, Table 22-1); however, 



mm 



the estimate for 1998 was less than 500. The cur- 

 rent population estimate for the eastern Bering Sea 

 stock is 7,986 based on surveys in 1992. 1>)')3, 

 and 1994. 



Minimum Population Estimate 



Ihe minimiHii population estimates for Alaska 

 beluga whale stocks are: 32,453 for the Beaufort 

 Sea stock; 3,710 for the eastern Chukchi .sea stock; 

 6,439 for the eastern Bering Sea stock; and 1,316 

 tor the Bristol Bay stock. The mininuim estimate 

 of abundance for Cook Inlet beluga whales is cur- 

 rently being revised, but will likely be less than 

 400 animals. 



Current Population Trend 



The Beaufort Sea stock ot beluga whales is 

 believed to be stable or increasing; the eastern 

 Chukchi Sea and Bristol Bay stocks are believed 

 to be stable. The population trend h)r the F'astern 

 Bering Sea stock is uncertain at this time. I he 

 Cook Inlet stock is likely declining. 



Status of Stock 



The PBR for Alaska beluga stocks are: 649 for 

 the Beaufoft Sea stock, 74 for the eastern Chukchi 

 Sea stock, 26 for the Bristol Bay stock, 1 29 tor the 

 eastern Bering Sea stock, and 14 for the Cook In- 

 let stock. This latter PBR will likely be reduced as 

 NMFS recently solicited information from the 

 public legarding the need to classify this stock as 

 endangered or threatened under the ESA or de- 

 pleted under the MMPA. The levels of human- 

 caused mortality and serious injury for these stocks 

 averaged over the past 5 years are: 1 60 tor the Beau- 

 fort Sea stock, 54 for the eastern Chukchi Sea 

 stock, 127 for the eastern Bering Sea stock, 26 for 

 the Bristol Bav stock, and 71 for the (!ook Inlet 

 stock. At this time, only the C^ook Inlet stock of 

 beluga whales has been classified as a strategic stock 

 under the MMPA. 



FOR FURTHER READING 



Hill. P. S., .uul D. P. DcMastL-r. in press. Al.isk.i ni.irine 

 mammal stock assessments: 1998. NDAA Technical 

 Memorandum NMFS-AFSC-97, 150 p. 



Hill, P. S., O. R DeMaster, and R. \. Sni.ill. 1 997. Alaska 

 marine m.immal stock assessments, 1996. U.S. De- 

 partment of C'ommerce, NOAA'I'echnital Memor.in- 

 dum NMFS-AFSC-78, 150 p. 



236 



