FISHERY BULLETIN: VOL. 83, NO. 3 



wintering area (Taber and Thomas 1982). 



Aerial activity similar to what we observed in the 

 eastern Beaufort Sea- breaches, tail slaps, pectoral 

 flipper slaps, and rolls- has been observed in bow- 

 heads during spring migration (Rugh and Cubbage 

 1980; Carroll and Smithhisler 1980). It appears that 

 aerial behavior is more frequent during spring 

 migration than on the summer feeding grounds, and 

 this may be related to the high levels of social-sexual 

 activities during spring. 



Comparisons with Other Baleen Whales 



Bowhead whales spend their entire lives in arctic 

 and near-arctic waters. This habit separates them 

 from all other baleen whales, which may move into 

 temperate or subtropical waters (Lockyer and 

 Brown 1981). However, behavior is in large part 

 determined by feeding mode and related ecological 

 factors (Gould 1982), and here similarities between 

 bowhead whales and several other species are evi- 

 dent. 



Gray, bowhead, and right whales are often found 

 in shallow water, and all three species feed on small 

 invertebrates. Gray whales usually feed near the bot- 

 tom (Bogoslovskaya et al. 1981; Nerini and Oliver 

 1983), whereas right and bowhead whales may skim 

 their food at or near the surface (see Watkins and 

 Schevill 1976, 1979 for right whales). But all three 

 species are adaptable in feeding behavior. Gray 

 whales apparently will feed on mysids associated 

 with kelp (Darling 1977) or on crab Pleuroncodes in 

 the water column (Norris et al. 1983). Right whales 

 also feed below the surface, probably straining 

 swarms of copepods and other small invertebrates in 

 the water column (Pivorunas 1979). While it has long 

 been known that bowhead whales feed at the surface 

 and in the water column (Scoresby 1820), it was 

 recently established from stomach content analyses 

 (Durham 1972; Lowry and Burns 1980), and by 

 observing bowhead whales surfacing with muddy 

 water streaming from their mouths (this study), that 

 bowheads sometimes feed near or on the bottom. It 

 is not surprising that there are many similarities in 

 the behavior of these species. Bowhead and right 

 whales, in particular, are morphologically and tax- 

 onomically quite similar, and appear to obtain their 

 food in very much the same ways. In fact. Rice 

 (1977). mainly relying on a detailed comparison of 

 morphology of bowhead and right whales, suggested 

 that they be put in the same genus, Balaena. 



The sleeker rorquals (Balaenopterid whales) 

 generally gather their food more actively by lunging 

 through concentrations of prey, and at least in the 



case of humpback whales, have developed compli- 

 cated behavioral strategies for confining and concen- 

 trating their prey (Jurasz and Jurasz 1979; Hain et 

 al. 1982). The rorquals are more often found in 

 deeper water far from shore, and their behavior in 

 general appears to be less similar to that of the 

 bowhead whale than its behavior is to that of gray 

 and right whales. 



Gray whales spend part of the winter in warm 

 water, near the shores of Baja California, and most 

 of the summer they feed in the northern Bering and 

 southern Chukchi Seas. Western Arctic bowheads 

 make much shorter migrations, spending their 

 winter in the pack ice of the Bering Sea and their 

 summer predominantly in the Beaufort Sea. The two 

 species thus use the Bering Sea at different seasons 

 and for different purposes -gray whales to feed in 

 summer and bowheads apparently to mate and calve 

 in winter. Like bowhead whales summering in the 

 Beaufort Sea, the primary activity of gray whales 

 summering in the Bering and Chukchi Seas is 

 feeding. However, both bowheads and gray whales 

 (Sauer 1963; Fay 1963) occasionally socialize during 

 summer. 



Right whales, like bowhead whales, often appear 

 to feed in the water column or at the surface 

 (Watkins and Schevill 1976, 1979) and may stay in 

 the same general area for days. While skim feeding, 

 both species at times aggregate into echelons. In 

 right whales, these echelons usually consist of only 

 3-6 whales (Payne, pers. obs.), while up to 14 bow- 

 head whales have been seen skim feeding in echelon. 

 However, Payne observed right whales during 

 winter when little feeding occurs, so apparent dif- 

 ferences in feeding details may be due to seasonal 

 factors. 



Apparent differences between the social activity of 

 bowheads and right whales may also be largely attri- 

 butable to the different times of year when they have 

 been studied. The same kinds of nudges and pushes 

 have been observed for interacting whales of both 

 species, but the winter-spring social activity of right 

 whales is much more boisterous than the summer 

 social activity of bowheads. Observations of bowhead 

 whales in spring indicate that their social-sexual acti- 

 vity at that season can be as boisterous as is seen in 

 mating groups of right whales (Everitt and Krogman 

 1979; Carroll and Smithhisler 1980; Rugh and Cub- 

 bage 1980; Johnson et al. 1981). The belly-up posi- 

 tion of a female bowhead photographed in spring in 

 the Alaskan Beaufort Sea (Everitt and Krogman 

 1979) indicates that females may attempt to evade 

 potential mates who pursue them in large mating 

 aggregations in the same way that female right 



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