Fishery Bulletin 94(1), 1996 



mm. The age of these individuals was estimated to 

 be less than one year (Arkhipkin and Bizikov, 1991). 

 Feeding, shoal, and escaping behaviors have also 

 been examined from manned submersibles (Alexeev 

 et al., 1989). 



The first studies on B. magister biology in the 

 Bering Sea appeared in the seventies ( Shevtsov, 1974; 

 Fedorets, 1977, 1979). During the next decade, in- 

 vestigations were focused on distribution and stock 

 dynamics (Fedorets, 1986a), feeding rhythms 

 (Fedorets, 1986b; Kuznetsova and Fedorets, 1987), 

 gametogenesis, fecundity, and spawning (Reznik, 

 1982; Fedorets and Kozlova, 1986). B. magister was 

 common along the continental slope of the Bering 

 Sea at depths varying from 100 to 1,500 m. In the 

 western Bering Sea, and near the Commander and 

 Aleutian Islands, dense seasonal aggregations 

 formed at depths ranging from 300 to 500 m. Accord- 

 ing to Fedorets and Kozlova (1986), spawning oc- 

 curred near the Commander Islands in winter and 

 in the northwestern part of the Bering Sea in sum- 

 mer. Hatchlings were hypothesized to be transported 

 by currents into the Bering Sea and Kurile Islands 

 region. Total stock size in the Bering Sea was esti- 

 mated to be about 350,000 t (Fedorets, 1986a). 



Research has been carried out on the presence of 

 intraspecific groupings of B. magister in the Sea of 

 Okhotsk (Nesis and Nezlin, 1993). However, genetic 



studies on protein variability have revealed a high 

 polymorphism and heterozygosity without any sig- 

 nificant differences within the species range 

 (Katugin, 1991, 1993). 



In contrast to a relatively good understanding of 

 distribution, reproductive biology, and genetic vari- 

 ability, the growth and age-length dynamics of B. 

 magister in the Bering Sea remain unknown. The 

 present paper describes distribution, length frequency, 

 stock-structure dynamics, and age and growth of B. 

 magister in the western Bering Sea by using statolith 

 and gladius ageing techniques. 



Materials and methods 



Data were collected on B. magister during seven trawl 

 surveys in the western Bering Sea flat. 59°30'N- 

 61°30'N; long. 166° 00'E-179°30'W) by three Japa- 

 nese trawlers: Tenyu-Maru N 57, Kaiyo-Maru N 28, 

 and Kashima-Maru N 8 between June and Novem- 

 ber 1993. Each survey was carried out during the 

 first 10-11 days of each month and consisted of 12 

 transects (Fig. 1 ). Additional surveys were performed 

 in the second half of June and November. On each 

 transect, three near-bottom trawls were made at 

 depths of 170-250 m, 370-450 m, and 600-750 m. 

 Trawls were conducted with the standard Japanese 





Figure 1 



Location of the twelve transects of the scientific survey on Berryleuthis magister in the western Bering Sea. 



