Carolina jetties, differences in fish 

 populations on old versus new jetties and 

 on ocean versus inlet sides of jetties 

 appear to be small compared to the major 

 differences in spatial use patterns 

 observed over depth gradients (Lindquist 

 et al . 1985). Of the nine abundant 

 species studied by Lindquist et al . , six 

 were significantly more abundant at a 

 depth of 2 m than at 4 m (pinfish, 

 spottail pinfish, sheepshead, pigfish, 

 bluefish, and round scad, Decapterus 

 punctatus ) , one was more abundant at 4 m 

 (black sea bass), and two showed no 

 significant changes in abundance between 

 these depths (tautog and spot). Van Dolah 

 et al . (1986) noted similar patterns for 

 several of these species on the South 

 Carolina jetties they studied; our 

 experience with the North Carolina jetties 

 at Cape Lookout, Shackleford Banks, and 

 Radio Island suggests that these patterns 

 occur on those jetties as well. 



The abundance of sparid fishes 

 (pinfish, spottail pinfish, and 

 sheepshead) is known to be positively 

 correlated with vegetation cover. Stoner 

 (1980b) demonstrated a very high 

 correlation (r = 0.998, p < 0.01) between 

 pinfish abundance and macrophyte biomass 

 in seagrass beds. Other authors have made 

 similar observations (Caldwell 1957; Kilby 

 1955; Schwartz 1964). It appears that the 

 sparids are abundant in shallow areas 

 because of the increased abundance of 

 seaweeds. Seaweeds are fed on directly 

 and also support populations of small 

 crustaceans that are another important 

 component of the sparid diet (Ogburn 1984; 

 Darcy 1985a, b) . Pelagic sport fishes, 

 such as bluefish and Spanish mackerel, may 

 be attracted to these shallower depths 

 because of the increased abundance of 

 sparids and other prey. 



As mentioned earlier, large seasonal 

 changes occur in the species composition 

 and abundance of fishes on rubble 

 structures in the South Atlantic Bight. 

 Numerous studies suggest that most of 

 these changes are driven by the need of 

 fishes to avoid the colder inshore water 

 temperatures that occur in winter 

 (Huntsman and Manooch 1978; Miller and 

 Richards 1979; Parker et al . 1979; 

 Lindquist et al . 1985; Van Dolah et al . 

 1986). Even though these seasonal 



temperature changes are less pronounced at 

 lower latitudes, the same general patterns 

 of offshore or southerly migrations appear 

 to occur throughout the entire South 

 Atlantic Bight. As an example, pinfish 

 and spottail pinfish undergo similar 

 patterns of seasonal migration in both 

 North Carolina and Florida (Adams 1976b; 

 Stoner and Livingston 1984; Darcy 1985a, 

 b). 



Seasonal patterns of abundance on 

 jetties in the bight have been studied 

 most extensively on the jetties at 

 Murrells Inlet, SC (Van Dolah et al . 1984, 

 1986). Abundance and community 

 composition of fishes frequenting these 

 jetties were assessed quarterly using gill 

 nets, visual observations, crab traps 

 modified to retain small fishes (6.4 mm 

 mesh), unmodified crab traps, and 

 qualitative rotenone collections. Gill 

 nets were run from the jetty to a distance 

 of 23 m away from the jetty to sample not 

 only resident jetty fishes, but also 

 pelagic predators preying on these fishes. 

 Crab traps were deployed on, or very near, 

 the jetties and thus assessed jetty fishes 

 that would enter traps. Visual counts by 

 divers provided an additional assessment 

 of noncryptic jetty fishes that may not 

 have been adequately sampled by the other 

 techniques. The qualitative rotenone 

 collections allowed a crude assessment of 

 small cryptic species like blennies and 

 gobies. Rotenone is a toxin that stresses 

 small fish, causing them to leave their 

 cryptic habitats and swim into the open 

 water where they can be collected. 



Data from these studies are shown in 

 Table 1 and in Figures 16-25. Most of 

 these data are reported in the literature, 

 and thus in our tables and figures, without 

 an indication of the variance (Van Dolah et 

 al . 1984, 1986). We have included 

 measurements of variance where they exist. 

 The only other available studies dealing 

 with fishes on jetties in the bight (Ogburn 

 1984; Lindquist et al . 1985; Hay 1986) are 

 less extensive but show similar patterns. 



The total number of fish species seen 

 in visual counts, or collected using gill 

 nets or modified crab traps, was highest 

 during warmer seasons of the year and 

 decreased markedly in winter (Table 1). 



25 



