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Fishery Bulletin 88(1), 1990 



the same hook-and-line method to capture Atlantic 

 spadefish for stomach content analysis, and similarly 

 found a preponderance of cannonball jellyfish in the 

 diet. Spearfishing may have introduced some bias as 

 well, since this method of collection concentrated on 

 nearbottom fish that were closely associated with the 

 artificial reefs. I obsen'ed that Atlantic spadefish spentl 

 some time higher in the water column, and schools 

 were occasionally seen at the surface. Atlantic spade- 

 fish have also b^en observed eating Stomolophus mele- 

 agris and ctenophores at the surface in artificial reef 

 areas (D.L. Hammond, SCWMRD, Charleston, SC 

 29412, pers. commun.. May 1987). Although few cteno- 

 phores were identified in this study, their importance 

 to the diet may have been underestimated since the 

 mutilation of ctenophores by ingestive and digestive 

 processes could have made them difficult to detect dur- 

 ing analysis of stomach contents. Although jellyfish oc- 

 curred in the stomach of only one Atlantic spadefish 

 obtained by spearfishing and nets, it was possible that 

 these organisms were more important in the diet than 

 indicated. However, they appear to he consideral)ly less 

 important than indicated by hook-and-line collections. 



The shift from a diet dominated by hydroids in strata 

 1 and 3 to a diet composed primarily of anthozoans in 

 stratum 2 was probably a reflection of differences in 

 food resources available in the different habitats. Juve- 

 nile Atlantic spadefish in estuaries (stratum 1) frequent 

 wharves, pilings, and piers (Hildebrand and Schroeder 

 1928) where hydroids are a major part of the fouling 

 community (Sutherland 1977). Hydroids are also a 

 dominant component of fouling communities on off- 

 shore structures (stratum 3) (Wendt et al. 1989). 

 Hydroids were probably less abundant in stratum 2 

 since unstable substrates, such as sand, generally sup- 

 port fewer hydroids (Calder 1976). However, sea 

 pansies are typically located in sandy bottoms (Barnes 

 1980) and have been reported as a benthic component 

 in South Carolina's sandy nearshore areas (Shealy et al. 

 1975, Van Dolah et al. i983). A similarity in the diets 

 of fish collected from strata 2 and 3 was the presence 

 of an appreciable amount of terebellid polychaete tenta- 

 cles. Perhaps polychaete tentacles and sea pansies 

 presented a somewhat similar target to C. faber since 

 both prey commonly feed with a mass of feeding struc- 

 tures extended from the sand; this suggested that a 

 grazing-type feeding behavior was taking place along 

 sandy bottoms. 



Examination of the differences in diets among size 

 classes of Atlantic spadefish showed all size classes 

 relied heavily on hydroids. Although young-of-the-year 

 fish in stratum 1 ate mainly hydroids and relied little 

 on anthozoans for food, the high value for Anthozoa 

 in the diets of small fi.sh (<101 mm SL) was a reflec- 

 tion of numerous young-of-the-year fish which were 



collected from stratum 2 in increasing numbers begin- 

 ning in the early fall. The high values for amphipods 

 in fish 101-200 mm SL was [irimarily due to unusual- 

 ly large numbers (>1200 individuals in one stomach) 

 found in three stomachs from a single collection at the 

 Murrell's Inlet jetties; a large volume of hydroids was 

 also present in these stomachs. Overall, major changes 

 in food habits within the size range examined were not 

 apparent; even the smallest fish examined (19 mm SL) 

 had eaten primarily hydroids. Differences that existed 

 probably reflected changes in habitat with increasing 

 size. No information is currently availal)le about food 

 habits of larval C. faber. 



Age and growth 



Some information is available about early development 

 of C. faber (Ryder 1887, Hildebrand and Cable 1938, 

 Johnson 1978); however this study presents the only 

 known information of this species' later growth with 

 age. Although the location of the first annular mark 

 on the otoliths has not been thoroughly validated, the 

 size of fish with only one opaque zone on the sagittae 

 corresponded well with the lengths of fish in the sec- 

 ond group of a size-frequency distribution (Fig. 6). This 

 also agreed with Hildebrand and Cable (1938), who be- 

 lieved Atlantic spadefish in North Carolina attained a 

 length of 55-100 mm by the end of the first summer 

 and a length of 135 mm (type of measurement unspe- 

 cified; probably TL) during their second summer. Con- 

 sequently, I am confident that the first opaque zone 

 is the first annulus. Since young-of-the-year Atlantic 

 spadefish are easily obtained from South Carolina 

 estuaries during the summer and they can survive 

 relatively well in captivity, more thorough validation 

 of the first annulus, as well as additional yearly marks, 

 may be obtained through daily growth studies and 

 marking of otoliths with a chemical such as tetracycline 

 (Beamish and McFarlane 1987). 



Marginal increment analysis supported the hypothe- 

 sis that the opaque zones on sagittae are annuli since 

 they appeared to be formed once a year (over the 

 winter months), although fish were available at collec- 

 tion sites only between May and December. In addi- 

 tion, the data showed (1) a strong relationship l)etween 

 otolith radius and length of the fish; (2) a decrease in 

 growth rate in length with age (except where obscured 

 by small sample sizes); and (3) close agreement between 

 back-calculated lengths and observed lengths at age. 

 The mean asymptotic TL (L^ = 490 mm TL) was 

 reasonable for South Carolina's Atlantic spadefish 

 population, but small for tropical regions where Atlan- 

 tic spadefish with lengths up to 900 mm (presumably 

 TL) have been reported (Breder 1948, Johnson 1978). 



