Abstract.— Distribution, abun- 

 dance, and length-frequency composi- 

 tion of schoolmaster gonate squid, 

 Berryteuthis magister, were studied 

 during seven trawl surveys in the west- 

 ern Bering Sea between June and No- 

 vember 1993. Statolith age analysis 

 was undertaken for 1,381 B. magister 

 to estimate age, stock structure, and 

 both growth and maturation rates. 

 Three kinds of growth increments were 

 revealed in B. magister statoliths. Daily 

 periodicity of the second-order incre- 

 ments was confirmed by two indepen- 

 dent, indirect methods. According to our 

 data, B. magister live >1 yr; the oldest 

 specimen was about 16 months old. 

 Berryteuthis magister is a slow-grow- 

 ing and slow-maturing squid, and 

 males exhibit slower growth and ear- 

 lier maturation than do females. 

 Growth in length was best described by 

 a logistic curve, with a larger asymp- 

 totic parameter for females. In summer, 

 concentrations of B. magister were low 

 within the whole region, whereas in 

 September-October squids aggregated 

 into dense shoals over the continental 

 slope of the Navarin-Olyutorsky region 

 and Olyutorsky Bay. Stock structure of 

 B. magister was complicated: each 

 month, from 5 to 12 (usually 7-8) 

 monthly classes of squid were encoun- 

 tered in the western Bering Sea. Three 

 seasonal groups ofS. magister occurred 

 in the region: winter-, summer- and 

 fall-hatched squids utilizing resources 

 of the continental slope in different 

 ways. A possible life cycle for the B. 

 magister fall-hatched group includes a 

 longevity of ca. 2 yr: 6 mo of embryonic 

 development and 18 mo of postembry- 

 onic growth. 



Distribution, stock structure, and 

 growth of the squid 

 Berryteuthis magister (Berry, 1913) 

 (Cephalopoda, Gonatidae) during 

 summer and fall in the western 

 Bering Sea 



Alexander I. Arkhipkin 



Atlantic Research Institute of Marine Fisheries and Oceanography (AtlantNIRO) 

 5 Dm. Donskoy Street, Kaliningrad. 236000 Russia 



Vyacheslav A. Bizikov 

 Vasily V. Krylov 



All-Russian Research Institute of Fisheries and Oceanography (VNIRO) 

 1 7 V-Krasnoselskaya Street, Moscow, 107140 Russia 



Kir N. Nesis 



PP Shirshov Institute of Oceanology of the Russian Academy of Sciences 

 23 Klasikov Street, Moscow, 1 17851 Russia 



Manuscript accepted 7 September 1995. 

 Fishery Bulletin 94:1-30 ( 1996). 



The schoolmaster gonate squid, 

 Berryteuthis magister (Berry, 1913), 

 is an abundant near-bottom species 

 occurring over the continental 

 slopes in the North Pacific from 

 southern Japan, the Sea of Okhotsk, 

 and the Kurile Islands to the north- 

 western coast of the United States 

 (Roper et al., 1984; Nesis, 1987). 

 This species is one of the important 

 fishery resources in the North Pa- 

 cific. It is captured mainly by Rus- 

 sian trawlers around the Kurile Is- 

 lands, in the Sea of Okhotsk, and 

 in the western Bering Sea with an 

 annual catch of 30,000-60,000 met- 

 ric tons (t) (Fedorets, 1986a). In 

 Japan, B. magister is taken season- 

 ally by the coastal fishery and yields 

 an annual catch of 5,000-9,000 t 

 (Kasaharaetal., 1978). 



Some aspects of the distribution, 

 reproductive biology, and growth of 

 B. magister have been investigated 

 in the Sea of Japan (Naito et al., 

 1977; Kasahara et al., 1978; Na- 

 zumi et al., 1979), where spawning 



occurs from December to May (with 

 a peak between February and 

 March). With the use of length-fre- 

 quency analysis, the life cycle of B. 

 magister was estimated to be 2 

 years or more, and growth of both 

 sexes was approximated with a lo- 

 gistic function (Yuuki and Kita- 

 zawa, 1986). Natsukari et al. ( 1993 ) 

 used statolith ageing techniques for 

 age and growth analysis of B. mag- 

 ister captured in Kitamiyamato and 

 Rebun Banks and suggested a lon- 

 gevity of four years, with females 

 attaining a larger size than males 

 at any given age. 



Patterns of vertical and spatial 

 distribution of B. magister juveniles 

 and adults were analyzed in the Sea 

 of Okhotsk and waters of the Kurile 

 Islands (Railko, 1983; Alexeev and 

 Bizikov, 1986; Nesis, 1989). Prelimi- 

 nary data on age were obtained by 

 comparing increment number be- 

 tween statoliths and gladii in five 

 immature specimens with mantle 

 lengths ranging from 220 to 250 



