ECOLOGY AND BIOLOGY OF THE PACIFIC WALRUS 



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area in May 1958 contained several whole valves, up to 2.5 cm in diameter, of 

 Cyclocardia sp. 



Stomachs of seven walruses taken in Norton Sound by Eskimos from Nome, 

 during May and June 1975, contained almost exclusively the feet of Serripes 

 groenlandicus. Minute quantities (< 1 % by volume) of Mya and Tellina and of 

 Neptunea, Natica, and Polinices also were present. 



In 77 walruses taken in the Bering Strait area by Eskimos from King and Little 

 Diomede islands in May and June 1975, the predominant items were siphons of 

 Mya spp., and Hiatella arctica, and feet of Serripes groenlandicus. Also 

 numerous but of secondar>' importance in volume were Priapulus caudatus, 

 Nephthys sp., Lumbrinereis sp., and Golfingia margaritacea, as well as Nep- 

 tunea, Buccinum, Natica and Polinices, Yoldiu hyperborea, Tellina lutea, and 

 Thyonidium commune. The small bivalve Hiatella arctica, whose contracted 

 siphon is only about 1 cm long and weighs about 1 g, was represented by 

 extraordinary' numbers of siphons in these stomachs. These were present in 55 of 

 the 77 walruses, 22 of which contained more than 500 of these siphons; 15 

 stomachs contained more than 1,000. The largest number in one stomach was 

 6,378. One stomach contained about 10.5 kg of flesh of the bearded seal along 

 with a few mollusks; one other contained a large volume of "sea anemones" 

 (actiniarian coelenterates) , tentatively identified as being of the genus 

 Metridium. 



Brooks (1954) examined an undisclosed number of stomachs from males taken 

 in Bering Strait in June 1952 and 1953, from which he concluded that they fed 

 there mainly on Mya truncata and Clinocardium nuttallii and to a lesser extent 

 on Molpadia arctica. Females and immature animals tended more toward taking 

 the smaller bivalves, such as Astarte sp. and Macoma calcarea, together with 

 Nephthys sp. and sipunculids. These differ from the findings in 1975 by Fay et al. 

 (1977), in terms of most of the genera and species identified. I am uncertain 

 whether this difference reflects a change in feeding habits or simply 

 misidentification of the specimens by specialists assisting Brooks. 



Summer: Bristol Bay. — I examined the contents of digestive tracts from three 

 males taken on Round Island in late June 1958, but found in them only fine 

 digesta and a few setae of Echiurus echiurus. Such setae were abundant also in 

 the feces from other walruses on the hauling grounds there at that time. The only 

 other items found (by K. W. Kenyon, personal communication) in the feces were 

 a few valves of Cyclocardia sp., the largest of which was 2.7 cm in diameter. 



Summer: Chukchi Sea. — Stomachs from 11 males taken near Barrow in July 

 and August 1952 and 1953 contained mainly siphons oi Mya truncata. The holo- 

 thurian Molpadia arctica ranked "a poor second" (Brooks 1954). Also present 

 were a few Priapulus, Sclerocrangon sp., Hyas coarctatus, and Neptunea sp. 

 L. M. Shults (personal communication) examined the contents of one other 

 stomach from that area in 1976 and found mainly Thyonidium commune, with 

 lesser amounts of Priapulus caudatus, Neptunea, Buccinum, and Natica. 



Nikulin (1941) reported the stomach contents of an unspecified number of 

 animals taken mainly in Bering Strait and the western Chukchi Sea in June to 

 August 1934, 1935, and 1937. He concluded from these that mollusks were the 

 most important prey, as indicated by the great number of genera (11) 

 represented. Of those, apparently, Astarte, Macoma, Serripes, and Mya were 



