Fishery Bulletin 98(1) 



During the first 10-day period of February, concen- 

 trations of /. argentinus were observed in all parts 

 of the region. Squid concentrated near the bottom 

 during the daytime and ascended to the upper water 

 layers at night. The CPUE was twice as high as in 

 January, and the squid fishery stabilized at 16-17 t/d. 

 However, aggregations of /. argentinus quickly dis- 

 persed, and during the second 10-day period of Febru- 

 ary, the CPUE fell sharply to the January level (Fig. 

 2). Catches of squid were low but stable (around 10 

 t) imtil the second 10-day period in April, when fish- 

 ing vessels shifted from the shelf edge ( 170-190 m 

 depth) to the continental slope (440-660 m depth) 

 and changed fishing tactics. The vessels performed 

 near-bottom trawls at the shelf edge during the day- 

 time, and on the continental slope at night. These tac- 

 tics considerably increased CPUE (up to 15-18 t/d) 

 for the third 10-day period of April and in the begin- 

 ning of May because the fleet began to target not only 

 shelf aggregations but also the slope aggregations of 

 /. argentinus that were beginning to appear at that 

 time. 



Region AT-AQ^S Fishing trawlers operated in this 

 region between February and the second 10-day period 

 of March. The fishing tactics were the same as those 

 used in the previous region. Abundance of/, argenti- 

 nus was considerably greater than that in the region 

 outside the EEZA (Fig. 2). The peak of CPUE was 

 observed in the third 10-day period of February 

 (51 t/d). 



Region SI-SZ'S All fishing vessels that had oper- 

 ated in the 47-49°S region moved to the fishing region 



west of the Falkland Islands during the second 10-day 

 period of March and fished there until the middle of 

 May (Fig. 2). The fishing tactics were different fi-om 

 those used in the two previous regions. Trawlers fished 

 for squid in midwater both at night and in the day- 

 time. CPUE in March-April was high, similar to those 

 in the 47-49°S region with a prominent peak (53 t) 

 during the second 10-day period of April. At the begin- 

 ning of May, CPUE decreased sharply and the fleet 

 ceased fishing for squid in the region. 



Sex ratios 



Region AS-AT'S The proportion of females was the 

 highest during the second 10-day period of January 

 (ca 80% of the total sample). From the end of Janu- 

 ary through the beginning of February, the proportion 

 of females decreased sharply (to 55—60%). Sex ratio 

 was close to 1:1 between the second 10-day period of 

 February and the first 10-day period of April, when 

 the proportion of females occurring on the shelf edge 

 decreased to 30%. However during the third 10-day 

 period of April on the continental slope at depths of 

 480 m, the sex ratio was found to be close to 1:1, and 

 females prevailed in catches (65%) at deeper depths 

 (630 m) (Fig. 3). 



Region 47-49°S Except the first 10-day period of 

 February (when the sex ratio was close to 1:1), males 

 always predominated in catches at a ratio of 2:1 (Fig. 3). 



Region 51-52°S The sex ratio was close to 1:1, but 

 the proportion of females tended to decrease from 55% 



to 45% (Fig. 3). 



60 - 



50 



40 



30 - 



LU 20 



Z) 



a. 

 o 10 



-• 45-47°S I 



- - ■- • 47-49°S 

 i— ■* — 51-52°S 





u 



-* —  — ^ 



12312312312312 

 Jan Feb Mar Apr May 



Figure 2 



Mean CPLIE (tons per vcs.sel day i of the Russian trawlers in the 

 lllex argentinus fi.shcry in three fishery regions of the Southwest 

 Atlantic in 1991: 4.5-47°S ibold solid line), 47-49°S (dotted linei 

 and .51-52°S (dashed line). 



Length and hatching-month composition 



Region 45-47°S During the second 10-day period 

 of January, June-hatched maturing females (modal 

 sizes 210 mm ML) and mature males (200 mm) 

 predominated in catches. The proportion of mature 

 May-hatched squid was low. Hatching-month com- 

 position changed considerably during the third 

 10-day period of January owing to an appearance 

 of maturing and mature May-hatched squid (males 

 of 200 mm and females of 220-250 mm ML) in the 

 region (Fig. 4). 



Massive appearances of dense schools of immi- 

 grating June and July-hatched immature and 

 maturing females (200-220 mm ML) and mature 

 males (200-210 mm ML) were observed in the 

 first 10-day period of February which resulted in a 

 double increase in CPUE of the fishing fleet (Fig. 

 2) and in corresponding changes in the hatching- 

 month compositions of squid: June-hatched squid 



