Arkhipkin et al.: Distribution, stock structure, and growth of Berryteuthis magister 



15 



E 

 z 



Number of statolith Increments 



Comparison of the dif- 

 ference between the av- 

 erage number of second- 

 order statolith growth 

 increments of females 

 representing the modal 

 size classes in two succes- 

 sive samples with the 

 number of days elapsed 

 between the samples 

 showed that their values 

 were very close (Table 3). 

 This provided further 

 confirmation of daily for- 

 mation of each second- 

 order increment. The re- 

 lationship between the 

 number of second-order 

 growth increments of 

 modal-size females and 

 their date of capture was 

 approximated well by lin- 

 ear regression (Fig. 8B; 

 Table 2). The estimated 

 slope value (1.011) was 



very close to 1, further suggesting that a second-or- 

 der increment may correspond to one day. 



Age structure 



Minimum age (40 and 47 days) was observed in two 

 juveniles of 26 and 24 mm ML, respectively, caught 

 in the Navarin-Olyutorsky region in July. The old- 

 est male (mature, 295 mm ML) that was aged was 

 473 days. The two oldest females (276 and 369 mm 

 ML) were also mature and were 479 days old. All 

 these animals were captured in June in the eastern 

 part of the Navarin-Olyutorsky region. During sum- 

 mer and fall, the stock structure of B. magister was 

 rather complex. Each month, both in Olyutorsky Bay 

 and the Navarin-Olyutorsky region, we captured squid 

 of 5-12 (usually 7-8) month classes (Figs. 9 and 10). 



Dates of capture 



Figure 8 



Validation of growth periodicity of statoliths and gladii in Berryteuthis magister. (A) Rela- 

 tionship between the number of second-order increments in the statoliths and the number of 

 increments in the gladii; (B I relationship between the number of second-order increments in 

 statoliths of modal-size females and the dates of their capture (cumulating from 1 January 

 1993). 



Olyutorsky Bay In Olyutorsky Bay (Fig. 9), May- 

 July hatched males (age: 310-390 d) and females 

 (age: 325-385 d) were the most abundant mature 

 animals in June. Immature females (age: 300-320 

 d) of 180-210 mm ML were hatched during July, 

 August (mainly ), and September and were not abun- 

 dant. Immature males of 150-210 mm ML were 

 hatched in August and September. 



In August, the stock structure of B. magister was 

 considerably different from that observed in June 

 (Table 4). Mature June- and July-hatched squids al- 

 most disappeared from catches. Immature and ma- 

 turing August- and September-hatched squid of 210- 

 270 mm ML (age: 320-350 d) prevailed among fe- 

 males, whereas among males the most abundant 

 were August-October hatched mature individuals of 

 180-240 mm ML (age: 300-350 d). Small maturing 



