arately from the other predation on these 

 species. The decline of Theragra over the 

 past 4 years as a fur seal food species may 

 indicate a reduced population; intensive bot- 

 tom fishing by the Japanese and Soviets 

 during the past few years coincides with the 

 decline of this species as a fur seal food. 

 No study of Theragra populations in the Bering 

 Sea has been made, however. 



SUMMARY 



The sixth year of pelagic fur seal research 

 under terms of the Interim Convention on 

 Conservation of North Pacific Fur Seals was 

 conducted in the Bering Sea from 1 July to 

 5 September 1963, 



Two purse seine vessels, the M/V Harmony 

 and the M/V Tacoma , were chartered in 

 1963. The vessels sailed parallel courses 

 from the Strait of Juan de Fuca to Unimak 

 Pass from 20 to 28 June. 



Of 82 seals sighted, 44 were seen on the 

 first and last days when the vessels were 

 within 75 to 100 miles of land. Offshore dis- 

 tribution of seals appeared uneven. The move- 

 ments of fur seals in offshore areas of the 

 eastern North Pacific are not fully known, 

 and information available is not adequate to 

 show population changes from year to year. 



A study was made of distribution, abundance, 

 and food habits of fur seals on their sumnner 

 range in the Bering Sea. To aid in the analy- 

 sis of data, the eastern Bering Sea was divided 

 into six major sectors centered between St. 

 Paul and St. George Islands. The sectors 

 were then divided into zones, each 30 nautical 

 miles wide and extending to the sector bound- 

 aries. 



The distribution of seals in the first three 

 zones of sectors 1 through 6 appeared uni- 

 form. Distribution in the outer zones appeared 

 uneven, with seal concentrations in areas of 

 abundant food supply. 



The variation in numbers of seals seen and 

 collected by 10-day periods was caused by 

 changes in the weather and the locality where 

 collections were made rather than by any 

 sudden rise or decline in the fur seal popula- 

 tion of the Bering Sea. 



Seals were seen in groups rather than in 

 large herds. In 1963, groups of one, two, 

 and three seals accounted for 90.3 percent of 

 the total sightings. 



Of 1,355 seals collected in 1963. Ill were 

 males and 1,244 were females. Five-year-olds 

 predominated among females. The relative 

 distribution of males and females, with only 

 three exceptions, was fairly uniform. 



Post partum females predominated in the 

 early July collections in sectors 1 and 2, 

 zones 3 and 4, and in the feeding areas of 

 the outer zones from mid-July to early Sep- 

 tember. 



The first adult males found away from the 

 Pribilof Islands were seen 5-20 miles north- 

 west of Akun Island on 31 July. In August they 

 were found widely scattered at sea. More 

 males were collected in Alaska waters than 

 in the waters off California, Oregon, and 

 Washington. 



Male and female seals were observed to- 

 gether at sea, and special efforts were made 

 to study mating of fur seals at sea. The infor- 

 mation obtained was inconclusive. 



The number of tags recovered by pelagic 

 vessels has steadily increased since 1958; 

 43 tagged animals were taken in 1963. 



The mean lengths of 4,074 pregnant, 1,528 

 post partum, and 2,353 nonpregnant females 

 collected from 1958 through 1963 are com- 

 pared. The lengths of nonpregnant and post 

 partum seals agree more closely than do 

 the lengths of pregnant and post partum 

 seals. For unknown reasons, pregnant fe- 

 males apparently decrease in length after 

 parturition. 



The average pregnancy rate of 84.1 percent 

 for females 6 years old and older is uniform 

 for the 6 collection years. This rate decreases 

 to 71.9 percent if 3-, 4-, and 5-year-old 

 females are included. 



The fur seal feeds exclusively on fish and 

 cephalopods. The species taken apparently 

 are controlled by quantity and availability of 

 fish and cephalopods rather than by a tendency 

 to be selective. 



Seals capture and consume prey varying 

 greatly in size. Food items ranging in length 

 from 5 to 45 cm. were removed from stomachs 

 collected in 1963. 



Small prey such as Mallotus , Ammodytes , 

 and squid usually are captured and consumed 

 below the surface while larger fish such as 

 Theragra generally are eaten at the surface. 

 Larger fish generally appear in seal stomachs 

 in chunks or with part of the body missing. 

 Theragra and Oncorhynchus identified in 

 stomachs in 1963 were found in this condi- 

 tion. 



The following fish and squids were identi- 

 fied from stomachs taken in 1963: Clupea 

 harengus pallasi (herring), Oncorhynchus sp. 

 (salmon), Mallotus villosus (capelin), Bathy- 

 lagidae (deepsea smelts), Myctophidae (lan- 

 ternfishes), Lampanyctus nannochir (lantern- 

 fish), Gadidae (cods), Theragra chalcogrammus 

 (walleye pallock), Sebastodes sp. (rockfish), 

 Pleurogrammus monopterygius (Atka mack- 

 e r e 1), Cottidae (sculpin), Cyclopteridae (lump- 

 suckers), Trichodontidae (sandfishes), Am- 

 modytes hexapterus (sand lance), Pleuronec- 

 tidae (righteye flounders), Reinhardtius hip- 

 poglossoides (Greenland halibut), Gonatidae 

 (squid), Gonatus fabricii (squid), Conatus mag- 

 ister (squid), and Gonatopsis sp. (squid). 



Reinhardtius hippoglossoides , Lampanyctus 

 nannochir , and Bathylagidae were identified 



