tal Shelf, most were in the vicinity of the Pribilof Islands 

 (Townsend 1935) and St. Matthew Island (Hanna 1920; 

 Braham et al. 1980c). In April 1976, at least two bowheads 

 were seen in outer and southern Bristol Bay representing the 

 most southeastwardly sighting of the species (Fig. 29). 



The northward spring migration of the bow head whale from 

 the Bering Sea is timed with the breakup of the pack ice (Bailey 

 and Hendee 1926; Foote 1964 2 '; Nishiwaki 1967; Durham 

 footnote 11). This generally occurs in April (Sleptsov 1961; 

 McVay 1973) or earlier in a mild ice year (as in 1979). At that 

 time, most whales travel north through the Strait of Anadyr, 

 between St. Lawrence Island and the Chukchi Peninsula, con- 

 tinuing north by northeast through the Bering Strait probably 

 on the Soviet side, west of Big Diomede Island (Braham et al. 

 1979). During an "average" ice year, apparently few animals 

 migrate through the eastern half of the northern Bering Sea — 

 heavier ice usually occurs there than to the west. Even so, 

 Eskimo whalers at Wales periodically take bowheads along the 

 Alaska coast near the Bering Strait (Marquette footnote 14; 

 Johnson et al. 1981). Most of the migrating animals have 

 passed through this corridor between St. Lawrence Island and 

 the coast of the Chukotka Peninsula by mid-May (Bailey and 

 Hendee 1926; Foote footnote 21; Durham footnote 10; Bur- 

 gess 1973; Braham and Krogman footnote 2; Braham et al. 

 1979, 1980c). 



Upon entering the Chukchi Sea the migration is northeast- 

 erly across outer Kotzebue Sound in leads occurring in the 

 flaw zone. A few whales move into a polynya that character- 

 istically forms between Kivalina and Point Hope, but most 

 whales move past Point Hope, some offshore to 45-90 km 

 (Braham et al. 1980b). A few whales might migrate into the 

 western Chukchi Sea in spring; however, this is unlikely since 

 pack ice is extensive with few leads north of the Chukotka 

 Peninsula (Braham et al. 1979; G. Fedoseev"). Apparently, 

 Siberian Eskimos living along the north side of the Chukotka 

 Peninsula did not hunt bowheads in the spring as did their 

 counterparts along the east side of the Peninsula (A. Berzin, 

 footnote 19). 



Proceeding northerly on a heading of 10°-20° magnetic 

 (Braham et al. 1980d) bowheads follow open leads north past 

 Cape Thompson and Point Hope and then northeasterly to 

 Cape Lisburne and Point Barrow. The migration past Cape 

 Lisburne seems to follow two or more corridors, depending 

 on the number of leads, 2-10 km offshore; sightings have 

 been made to 15 km offshore (Rugh and Cubbage 1980). No 

 bowheads have been observed in offshore leads between 

 Point Lay and Point Barrow during 4 yr of aerial surveys, 

 even though aerial survey time has been split equally between 

 offshore (to 100 km) and nearshore coverage (Braham and 

 Krogman footnote 2; Braham et al. 1979, 1980c, d). The 

 majority of bowheads have usually passed Point Hope by 

 mid-May (Foote footnote 21; Johnson et al. 1966) and occur 

 in peak numbers at this time at Point Barrow (Maher and 

 Wilimovsky 1963; Fiscus and Marquette footnote 18; Bra- 



ham and Krogman footnote 2; Braham et al. 1979, 1980c). 

 The migration along the northwest coast (Bering Strait to 

 Point Barrow) essentially covers the period mid-April to early 

 June, with a few whales migrating by thereafter, according 

 to our work to date. 



Previous authors and numerous Eskimo whalers describe 

 the bowhead migration as occurring in three waves or pulses 

 of whales that pass by the northwest coast each spring (Foote 

 footnote 21; Marquette footnote 14). Examination of Figure 

 3 confirms that at least two pulses of whales migrated past 

 Point Barrow in 1976, 1977, and 1978. These pulses appeared 

 to occur in late April-early May and again near mid-May. A 

 third pulse may occur in late May or early June; but our data 

 either do not support this or the peak is small. The signifi- 

 cance of this bimodal, or trimodal, distribution is not clear, 

 but Eskimo whalers associate it with age, sex, and/or segre- 

 gation of cow-calf pairs from other adults in the population. 

 This cannot be confirmed from sightings and harvest data 

 collected between 1975 and 1980. 



From Point Barrow the whales travel northeasterly into the 

 Beaufort Sea to Banks Island and Amundsen Gulf, Canada, 

 some by early May (Braham and Krogman footnote 2; Fraker 

 et al. 1978; Braham et al. 1979). Leads do occur closer to 

 shore, but no whales were seen in them (Figs. 10, 15, 18), nor 

 are the nearshore leads extensive. Further evidence in support 

 of the hypothesis that bowhead and white whales migrate 

 offshore in the Beaufort Sea in the spring independently pro- 

 posed by Braham and Krogman (footnote 2) and Fraker 

 (1977)=' is reported in Braham et al. (1979, 1980d). The por- 

 tion of the population which enters Canadian waters com- 

 pared with the number passing Point Barrow is unknown. In 

 the Canadian Beaufort Sea bowheads remain from May until 

 late August or September (Cook 1926; Townsend 1935; Foote 

 footnote 21; Sergeant and Hoek 1974; Fraker et al. 1978) be- 

 fore beginning the return autumn migration west. From June 

 to September bowheads are reported to frequent Amundsen 

 Gulf, Franklin Bay, Coronation Gulf, the east side of the 

 Mackenzie Delta, and various areas south of Banks Island 

 (Cook 1926; Townsend 1935; Anderson 1946; Porsild 1950; 

 Manning and MacPherson 1958; Sergeant and Hoek 1974; 

 Allen 1978; Fraker et al. 1978). 



In August and September bowheads begin to leave the 

 eastern Beaufort Sea on their autumn migration back to the 

 Bering Sea (Cook 1926). The whales travel west in the south- 

 ern Beaufort Sea, where they are hunted during September 

 and October by Alaskan Eskimos from Kaktovik, Nuiqsut, 

 and Barrow (Brower 1942; Maher and Wilimovsky 1963; 

 Marquette footnote 14). Whales traveling this route have 

 been sighted or harvested near Herschel Island (Cook 1926; 

 Townsend 1935); Barter Island (Marquette footnote 14), 

 Cross Island 24 ; Colville River and Harrison Bay (Brower 

 1942); and Cape Simpson and Plover Islands (Braham and 

 Krogman footnote 2; A. Brower 5 ). Their spatial distribution 

 from the shore to the pack ice during the autumn migration 

 is not known, but it is likely to be dependent on ice condi- 

 tions, food availability, and water depths. Sightings made in 



! 'Foole, D. C. 1954. Observations of the bowhead whale al Pt. Hope. Alaska. 

 Unpubl. manuscr., 73 p. Nail. Mar. Mammal Lab.. Nail. Mar. Fish. Serv., 

 NOAA. 7600 Sand Poinl Way NE., Bldg. 32, Sealile, WA 981 15. 



"G. Fedoseev, Pacific Scientific Research Institute of Fisheries Oceanography, 

 Magadan, Nagaevskaya, 51, 685013, U.S. S.R., pers. commun. 28 February 

 1979. 



"'Fraker, M. A. 1977. The 1976 white whale monitoring program, Mackenzie 

 Estuary, N. W.T. Imperial Oil Ltd. Unpubl. rep., 73 p. F. F. Slancy & Co., Ltd., 

 Vancouver, B.C., Can. 



! 'T. Brower, Barrow, Alaska, pers. commun. 4 October 1977. 



"A. Brower, Barrow, Alaska, pers. commun. 19 May 1978. 



18 



