Hayse: Feeding, age, growth, and reproduction of Chaetodipterus faber 



11 



Figure 8 



Mean observed, mean back-caicuhited. and theoretical (von Berta- 

 lanffy) total lengths (mm) at age for both sexes of Chaetodipter'us 

 faber from South Carolina waters. 



states of atresia were observed in some histological 

 sections of ovaries which also contained developing 

 oocytes, indicating that some serial spawning took 

 place during the period May- August. 



Discussion 



Analysis of stomach contents 



Dietary analysis indicated that Chaetodipterus faber in 

 South Carolina eat mostly hydroids, anthozoans such 

 as sea anemones and sea pansies, and polychaete tenta- 

 cles. Pearce and Stillway (1976) reported the presence 

 of an unusual fatty acid in the liver of C. faber. Since 

 coelenterates appear to be the source of this fatty acid 

 in certain fishes and marine turtles, the authors sug- 

 gested that the elevated levels in Atlantic spadefish 

 could be a reflection of a high dietary intake of coelen- 

 terates. Gallaway et al. (1981) believed that the hy- 

 droids and other fouling organisms they observed in 

 the stomachs of Atlantic spadefish were being taken 

 from the water column after being sloughed off the 

 understructure of oil platforms. My underwater obser- 

 vations while SCUBA diving provided no evidence that 

 Atlantic spadefish are primarily planktivores as sug- 

 gested by Gallaway et al. (1981) and I never observed 

 anything to suggest that the ingested hydroids were 



Figure 9 



Maturity stages of age-1 and older (_'h<ietodipterus faber, by month 

 of capture in South Carolina waters, to illustrate spawning period. 

 Fishes were grouped according to those with gonads that were 

 developing or ripe and those with gonads that were spent or resting. 

 Numbers over bars are sample sizes. 



being culled from the water column. The results of this 

 study agreed with the assessments of Gallaway et al. 

 (1981) and Randall and Hartman (1968) that sponges 

 comprise a portion of the diet. Randall and Hartman 

 (1968) also found that zoantharians, polychaetes, and 

 tunicates were a portion of the stomach contents of 

 Atlantic spadefish. 



Although the IRI indicated that amphipods were 

 highly important in stomachs obtained by nets and 

 spearing, the numerical bias against the colonial and 

 soft-bodied organisms made it difficult to determine the 

 relative importance of prey of Atlantic spadefish with 

 this index. For this reason, the MI was a more reliable 

 measure of relative importance of food in stomachs of 

 C. faber. If only soft-bodied and colonial prey were in- 

 volved, the IRI would serve quite adequately; however, 

 when noncountable and countable organisms occur in 

 the same stomachs, numerical bias will make such an 

 index less indicative of the relative importance of dif- 

 ferent prey. Although it is possible that Atlantic spade- 

 fish eat hydroids as a means of simplifying capture of 

 epifaunal invertebrates (such as amphipods) that are 

 usually associated with hydroids, the frequent occur- 

 rence of other cnidarians, such as sea anemones and 

 sea pansies (which appeared to support fewer epifaunal 

 invertebrates) in the diet, suggests otherwise. 



The diet of C. faber collected by hook-and-line was 

 tiuite different from that of fish obtained by nets and 

 spearfishing. Hook-and-line sampling apparently 

 created a biased overestimate of the importance of 

 jellyfish in the diet of C. faber. Moore et al. (1984) used 



