A. Penaeus setiferus B. Penaeus aztecus 



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'. Xiphopenaeus D. Callinectes sapidus 



kroyeri 



Figure 6. — Annual variation in the transformed [log l0 (j: + 1)] mean number of 

 individuals of four major decapod crustacean species collected in the Cooper 

 River-Charleston Harbor estuarine system, 1973-77. 



Penaeus aztecus, Brown shrimp. — Brown shrimp were 

 highly seasonal in their occurrence within the Cooper River- 

 Charleston Harbor estuarine system. They were collected May 

 to September and were most abundant during June and July at 

 higher salinity stations (Fig. 5B). Annual catch rates were 

 variable and highest in 1974 and 1976 (Fig. 6B). Juvenile 

 brown shrimp entered the estuary in spring, remained through 

 the summer, and were almost totally absent from fall and 

 winter collections. This seasonal abundance pattern has also 

 been noted in other South Carolina estuaries (Bishop and 

 Shealy 1977), although the absence of brown shrimp from 



these estuaries during winter is probably due to gear bias for 

 larger-sized shrimp (Wenner et al. 1982). 



Xiphopenaeus kroyeri, Seabob.— Seabob were limited to 

 higher salinity areas of the estuary during fall and winter 

 (Fig. 5C). Annual catches were low, and no seabob were col- 

 lected in 1973 and 1977 (Fig. 6C). Although X. kroyeri occurs 

 in the lower portion of estuaries, it is most commonly encoun- 

 tered in the near offshore coastal zone (Gunter 1950). 



Callinectes sapidus, Blue crab.— Blue crab were collected 

 throughout the Cooper River-Charleston Harbor system, but 

 occurred year-round only at stations C004 and J001 (Fig. 

 5D). Crab were also least abundant at stations upriver. Annual 

 catches increased over the 5-yr sampling period except for a 

 slight decline in 1977 (Fig. 6D). Size-frequency distributions of 

 blue crab covered a wide range of sizes from 10 to 100 mm 

 carapace width with small crab ( < 60 mm CW) present during 

 all seasons. Average sizes of blue crab were generally larger in 

 spring and summer. 



Biomass Estimates 



Biomass and density for fishes were greatest at higher salin- 

 ity stations J001 and C004 during winter and spring (Table 7). 

 Increased values during these time periods were coincident 

 with the increased dominance of catches by Stellifer lanceola- 

 tus, Brevoortia tyrannus, and Micropogonias undulatus. 

 Decapod biomass and density were greatest at station J001 in 

 Charleston Harbor and during fall and summer for all stations 

 combined. These seasonal peaks coincided with periods when 

 young-of-the-year shrimp became vulnerable to our trawl 

 gear. 



Our mean total biomass and density estimates for all seasons 

 and stations sampled in the Cooper River-Charleston Harbor 

 system over the 5-yr study period were: 





Biomass (kg/ha) 



Density (no. /ha) 



Fishes 



6.04 



471 



:apods 



4.98 



678 



These estimates are comparable to those obtained by Wenner 

 et al. (1982) for estuarine portions of the Santee River system 

 of South Carolina and by Shealy et al. (1974) for estuarine 

 portions of the Cooper River-Charleston Harbor and Edisto 

 River systems. 



Table 7. — Average seasonal biomass (kg/ha) and density (no. /ha) of fishes and decapod crustaceans col- 

 lected at stations in the Cooper River-Charleston Harbor estuarine system, S.C., 1973-77. 











Average biomass and density/station 







Gr 

 m< 



and 





C002 



C003 



C004 



J001 



J003 



an 



Season 



kg/ha 



no. /ha 



kg/ha 



no. /ha 



kg/ha no. /kg 



kg/ha 



no. /ha 



kg/ha 



no. /ha 



kg/ha 



no. /ha 













Fishes 















Fall 



3.62 



166 



2.63 



202 



7.55 592 



11.03 



542 



4.30 



888 



5.37 



472 



Winter 



3.53 



175 



3.78 



258 



16.48 621 



14.52 



976 



6.52 



558 



8.60 



480 



Spring 



1.75 



428 



5.25 



242 



13.94 763 



11.99 



1,071 



6.06 



636 



7.45 



589 



Summer 



0.86 



97 



2.44 



289 



2.49 252 

 Decapods 



5.30 



602 



4.59 



593 



2.95 



346 



Fall 



1.57 



521 



6.71 



1,122 



9.35 1,380 



15.60 



1,993 



6.68 



915 



7.31 



1,116 



Winter 



0.05 



8 



0.22 



17 



0.77 143 



2.03 



314 



6.40 



931 



1.74 



260 



Spring 



0.06 



10 



0.53 



58 



5.10 376 



17.80 



1,270 



2.27 



287 



4.26 



339 



Summer 



0.90 



221 



12.20 



2,078 



5.26 928 



12.10 



1,288 



3.18 



338 



6.28 



943 



13 



