Griffiths: Life history and stock separation of silver kob, Argyrosomus inodorus 
59 
100% 
80% 
60% 
40% 
20% 
Females 
n = 1 ,434 
□ Stage 7 
■ Stage 6 
□ Stage 5 
m Stage 4 
□ Stage 3 
□ Stage 2 
AMJ JASONDJ FMAMJ JASONDJ 
Males 
n = 784 
□ Stage 7 
■ Stage 6 
□ Stage 5 
□ Stage 4 
□ Stage 3 
□ Stage 2 
AMJ JASONDJ FMAMJ JASOND J 
1 990 1 1 991 h- 
Figure 10 
Monthly percentage of gonad stages for mature female and male Argyrosomus 
inodorus in the southeastern Cape, April 1990-January 1992. n=sample size. 
tified as “A. hololepidotus”) as small as 1.3 cm TL 
just behind the breakers (5-7 m depth) in Algoa Bay. 
Voucher specimens (including otoliths) from both of 
these studies were identified as A. inodorus. There 
is therefore a trend of increasing length with increas- 
ing depth and distance from the shore for juvenile 
silver kob occurring between Cape Agulhas and Port 
Alfred. This finding suggests that juveniles are re- 
cruited to the nursery grounds just seaward of the 
surf zone and that they move farther offshore as they 
grow. Silver kob do not enter estuaries, and between 
Cape Agulhas and the Kei River, they do not occur in 
the surf zone (Griffiths and Heemstra, 1995). The 
SCBS CPUE-analyses revealed that juvenile A. 
inodorus were not homogenously distributed over the 
survey area but were found mostly in <120 m depth 
and comprised two disjunct distributional ranges, i.e. 
Cape Agulhas to Mossel Bay and Cape St Francis to 
Port Alfred (Fig. 3). Although the inshore areas of 
the southwestern Cape are not suitable for trawl- 
ing, analysis of commercial beach-seine catches 
(Lamberth et al., 1994) revealed that juvenile A. 
inodorus (identified as “A. hololepidotus ”) are also 
found in False Bay. 
Discussion 
The results of this study strongly suggest that silver 
kob between Cape Point and the Kei River comprise 
three discrete stocks. The foci of each of these stocks 
are False Bay in the southwestern Cape, Stil Bay in 
the southern Cape, and Port Alfred in the southeast- 
ern Cape. Tagging evidence indicates that there is lim- 
