Walrus (Odobenus rosmarus) 



The shallow waters of the Chukchi Sea are 

 the main summer ground of the Walrus in the 

 Pacific sector. Most females and young stay in 

 the western Chukchi while the majority of in- 

 dividuals in the area of Barrow are males. The 

 species is unusual east of Barrow. Walrus move 

 north in the spring and early summer on ice 

 floes reaching Point Barrow in mid-July and 

 start their southward migration toward the 

 Bering Sea in mid-September (Brooks, 1954). 



We observed Walrus primarily in the north- 

 east portion of the study area (fig. 38). All 

 large groups were seen in ice areas and most 

 were hauled out on ice floes (fig. 39). The 

 largest single sighting was of a loose concen- 

 tration of approximately 525 individuals seen 

 25 miles northwest of Point Lay. We observed 

 females with small young on six occasions 

 throughout the cruise. 



Walrus feed by foraging in water up to 40 

 fathoms deep for benthic organisms, par- 

 ticularly bivalve molluscs, other invertebrates 

 and occasionally Arctic Cod. At Barrow the 

 mollusc Mya truncata is their primary food 

 (Brooks, 1954). They stir up bottom sediments 

 with their tusks, sort out food with their lips 

 and whiskers and presumably suck out the 

 contents rejecting the shells. 



Seals (Phocidae) 



Seals were seen throughout the cruise 

 though few were observed well enough to be 

 reliably identified to species (fig. 40). The 

 Harbor (Phoca vitulina), Ringed (Pusa 

 hispida), Ribbon (Histriophoca fasciata) and 

 Bearded Seals (Erignathus barbatus) are 

 found in the Chukchi all year with the Ringed 

 Seal being the most common and the Ribbon 

 only a rare vagrant. 



The three common Chukchi species appear to 

 be ecologically distinct. The Harbor Seal is an 

 inshore species frequenting estuaries and sand 

 bars. It avoids heavy ice and feeds largely on 

 fish, the species varying seasonally. Presum- 

 ably seals seen in the open waters of the la- 

 goons and near the barrier beach at Point Lay 

 on 26 September and 5 October were this 

 species. The Ringed Seal frequents open water 

 leads in areas of fa.st ice but avoids the open 

 sea and floating ice. It feeds on small pelagic 

 crustaceans and to a lesser extent on fish in- 



cluding Arctic Cod. The many seals observed 

 swimming near ice oflfshore were identified as 

 this species. The Bearded Seal inhabits shallow 

 waters near coasts and unlike the other two 

 species, displays little gregariousness. Individ- 

 uals rest on beaches and ice floes and although 

 they do not migrate, they tend to move north 

 and south with the drifting ice. Their food 

 consists of benthic organisms-crustaceans, 

 holothurians, clams, snails, whelks, octopus, 

 and bottom fish. The majority of the numerous 

 individuals that were hauled out on the ice on 

 transects late in the cruise was identified as 

 Bearded Seals on the basis of muzzle shape. No 

 Ribbon Seals were seen on the cruise. 



Whales (Cetacea) 



We observed whales on only three occasions 

 during the cruise. At 71°08'N, 158°55' W on 

 24 September and at 70°34'N, 163°16'W on 

 1 October we tentatively identified single indi- 

 viduals as Bowhead Whales (Balaena mys- 

 ticetus). Both were near pack ice. A group of 

 five to eight Killer Whales (Orcinus orca) was 

 observed in a lead in the ice at 70°05' N, 

 168 "53' W on 8 October pursuing a female 

 Walrus with a young one on her back. 



The Bowhead Whale is associated with ice 

 and is present in the Chukchi Sea during the 

 winter, but tends to move even further north 

 in the summer. It is hunted by the eskimos but 

 is protected from commercial exploitation. 

 During the summer this baleen species, which 

 feeds on .small planktonic organisms, is re- 

 placed by the Grey Whale, Eschrichtitis gib- 

 bostis in the Chukchi. This latter species 

 presumably already had migrated south in late 

 September for we saw none during the cruise. 

 A few Killer Whales presumably stay in the 

 Chukchi all year wherever there is open water. 

 They travel in groups and feed on seals, young 

 Walruses and even porpoises and other whales. 



MIGRATION AND POST-BREEDING 

 DISPERSAL MOVEMENTS 



We saw no shearwaters or fulmars, except in 

 the Bering Strait, no pond ducks nor geese, no 

 shorebirds save phalaropes, no Arctic Terns, 

 and no Grey Whale.s — all species that have been 

 commonly recorded in the Chukchi Sea by other 

 observers earlier in the season. The only 

 Sabine's Gulls that we saw there were in the 



124 



