(Fig. 3G). Although silver perch were present in the Cooper 

 River-Charleston Harbor system throughout the year, 

 abundance of the species was greatest from August through 

 January. Annual catches decreased in 1977 (Fig. 4G). The 

 presence of silver perch throughout the year in estuaries of 

 South Carolina (Shealy et al. 1974; Wenner et al. 1982) differs 

 from the seasonal pattern observed in Chesapeake Bay. Chao 

 and Musick (1977) noted that most silver perch leave the York 

 River estuary of Virginia by November. They collected no 

 silver perch from January to March and suggested that the 

 year-round presence of the species in estuaries south of Chesa- 

 peake Bay may be due to the higher salinity or temperature of 

 those waters. 



were collected at the most seaward stations, with maximum 

 abundance occurring at the mouth of the estuary. Little 

 variation in annual catches of spotted hake was present in our 

 samples (Fig. 41). 



Trinectes maculatus, Hogchoker. — Trinectes maculatus 

 were collected sometime during the year at every station in the 

 Cooper River-Charleston Harbor system. Hogchoker were 

 most consistently abundant at stations upriver (C002 and 

 C003) and displayed no apparent seasonality in abundance 

 (Fig. 3J). Annual catches of hogchoker increased over the 5-yr 

 sampling period and were greatest in 1976 and 1977 (Fig. 4J). 



Cynoscion regalis, Weakfish. — Weakfish were collected at 

 all stations except C001 and were most abundant during sum- 

 mer (Fig. 3H). Annual catches were fairly constant with little 

 variation about the grand mean (Fig. 4H). The average length 

 of weakfish did not differ markedly by season, but length- 

 frequency distributions showed that the modal length for 

 spring catches was usually smaller than for other seasons. 

 This reduction in size is probably caused by increasing 

 numbers of young-of-the-year weakfish, newly recruited from 

 the May- August spawning period (Lunz and Schwartz 1970). 



Urophycis regia, Spotted hake. — Spotted hake displayed the 

 most seasonality in its distribution and abundance, being 

 collected from February to May only (Fig. 31). Their absence 

 from South Carolina estuaries during the rest of the year is 

 attributed to offshore migration to deeper water during 

 warmer months (Hildebrand and Cable 1938). Spotted hake 



Penaeus setiferus, White shrimp. — Catches of white shrimp 

 were seasonal with most individuals occurring late summer 

 through fall. White shrimp were also most numerous at the 

 downriver stations (Fig. 5A). Length-frequency distributions 

 indicated that young-of-the-year white shrimp were present in 

 the Cooper River-Charleston Harbor system during summer 

 and fall. Most shrimp collected during these seasons were <80 

 mm TL, except in 1977 when a few shrimp > 120 mm TL 

 were collected in summer and fall. The absence of young- 

 of-the-year shrimp in 1977 is also reflected in the annual catch 

 data for that year when a marked decrease in abundance of 

 white shrimp occurred (Fig. 6A). Modal lengths of white 

 shrimp generally increased during spring to > 100 mm TL. 

 The larger size of shrimp during spring is attributable to 

 shoreward migration of large shrimp from offshore waters 

 (Williams 1955) or to the growth of overwintering shrimp to 

 subadult size (Bishop and Shealy 1977). 





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Figure 5. — Abundance, expressed as the antilog of the transform- 

 Mi [logio (x i 1)] mean number of individuals at each station each 

 nonth, of four major species of decapod crustaceans collected in 

 he channel of the Cooper River-Charleston Harbor estuarine 

 system, 1973-77. Legend indicates four arbitrary levels of abun- 

 iance, from rare or absent (0-1) to maximum abundance 

 101-1,340). 



12 



