FISHERY BULLETIN: VOL. 84, NO. 3 



Table 12. — Instantaneous (Z) and actual (>A) rates of total mortality for Centropristis 

 striata in the South Atlantic Bight. Gear types: T = trap; H&L = hook and line. 



rate of total mortality from trap data and the South 

 Carolina commercial landings from 1978 to 1982 

 (Fig. 10). 



Population Estimates at 

 Specific Sites 



Mortality of C. striata attributable to tagging 

 occurred only once, during the 1983 experiment of 

 site 2 when 6% of the fishes (3 of 50) died during 

 the holding period. Therefore, we reduced the 

 number of tagged fish-at-large (M) by 6% to account 

 for this tagging related mortality. 



Between 1981 and 1983, a decline in the order of 

 magnitude from 20,070 to 2,236 individuals (88.9%) 

 occurred in the estimated abundance of C. striata 

 at site 1. On this reef, the abundance declined 60.6% 

 from 1981 to 1982 and another 75.5% from 1982 to 



1983 (Table 13). Abundance at site 2 declined 52.9% 

 between 1982 and 1983. Biomass of C. striata 

 declined by an order of magnitude on site 1 from 

 4,836 kg in 1981 to 491 kg in 1983 (Table 13). This 

 was an overall decrease of 89.9%. Site 2 had a 62% 

 decline in biomass from 2,150 kg in 1982 to 810 kg 

 in 1983. Our estimates are for fish >20 cm TL, 

 the only ones vulnerable to the traps. Therefore, 

 density and biomass estimates are minimum val- 

 ues. 



In addition to the declines in population size and 

 biomass of C. striata, there were decreases in mean 

 size and age. Mean TL was 3 cm less in 1983 than 

 in 1981 at site 1, whereas C. striata were on average 

 2 cm smaller in 1983 than 1982 at site 2. Not only 

 were the means reduced, but also the frequency 

 distribution became more skewed towards the 

 smaller size intervals and the contributions of larger 



Figure 10.— Plot of the instantaneous rate of 

 total mortality (Z) as determined from resource 

 survey data (1978-81) and the South Carolina 

 commercial landings of Centropristis striata 

 for that year. 



736 



Cfl 1 3 

 >> 



O 



o 



o 



CO 



OS 



.5- 



r-0.970 



100 200 300 



South Carolina Commercial Landings(metric tons) 



