696 



Fishery Bulletin 100(4) 



40 

 30 

 20 

 10 



40 

 30 

 20 

 10 



20 



Region iso 

 160 



"•-— 400 



Region 2 



10 



bti 



300 30 

 200 20 

 100 10 



O 



c 



Region 6 i „. 

 ^ 1 25 



Region 3 



30 

 20 

 10 



I 



.— fl ° '^ ^ * a " 



JFMAMJJASOND 

 Month 



: \ji 



JFMAMJJASOND 

 2^° Month 



200 

 150 

 100 

 50 



20 



15 

 10 

 5 



Figure 3 



Catches of Thyrsites atun made by South African commercial trawlers (bars I and line 

 fishermen (black circles) summed on a monthly basis in each region and expressed as 

 percentages of the total catch for the period 1985-1997. Mean monthly catch per unit 

 of effort (kg/boat/day) of T! atun caught by South African commercial line fishermen 

 in each region (open circles) is also given (1985-97). Because the bulk (70 ^t) of the 

 line catch in region 5 was made on offshore pinnacles (i.e. over a 72-mile bank), the 

 CPUE trend for this region was based on data from this area. The offshore pinnacles 

 (the 7'2-mile bank being the deepest) are, however, located well inshore of the trawl 

 grounds in that region (see Fig. 1). 



Spawning 



Gonadosomatic indices (Fig. 8) and gonad maturity indi- 

 ces (Fig. 9) showed that South African snoek spawn from 

 May to November and that peak spawning occurs from 

 June to October (winter-spring). Monthly male GSIs 

 were similar inshore and offshore, but female values were 



higher offshore during the spawning season. In addition, 

 a substantial proportion (20-i-%) of offshore females in 

 regions 2 to 5 had hydrated oocytes (stage 4), whereas this 

 gonad stage was rarely observed inshore. Spatial patterns 

 in trawl CPUE from both fishery-independent (Fig. 2) and 

 fishery-dependent (Fig. 10) data collected during winter- 

 spring suggest an extensive spawning gi'ound that encom- 



