SEDBERRY: FEEDING HABITS OF WHITEBONE PORGY 



predator species (Clifford and Stephenson 1975; 

 Boesch 1977). Only prey items that were identi- 

 fied to species were included in the similarity 

 analyses. To reduce the data matrix to a size that 

 could be accommodated by the computer pro- 

 gram and to eliminate very rare prey species 

 that were not important in the diet of any sparid, 

 only prey species that occuri'ed more than once 

 were included in the analysis. 



RESULTS 



Whitebone porgy were common in all three 

 depth zones, but they were more abundant at 

 middle and outer shelf stations (5.6 and 5.8 fish 

 per tow, respectively) than on the inner shelf 

 (2.6 fish per tow). Other sparids examined over- 

 lapped in depth distribution with whitebone 

 porgy. Sheepshead occurred at inner (1.7 fish 

 per tow) and middle (0.2 per tow) shelf stations. 

 Pinfish (6.2, 1.1, and < 0.1 fish per tow for inner, 

 middle, and outer shelf stations, respectively) 

 and southern porg>' (376.8, 562.8, and 0.9 fish 

 per tow) occurred in all three depth zones; red 

 porgy was collected only on the middle (1.4 fish 



per tow) and outer (5.6 fish per tow) shelf sta- 

 tions. 



Whitebone porgy stomachs (A^ = 219) con- 

 tained at least 135 species of invertebrates and 

 fishes. Decapods were the most important prey 

 and ranked high in frequency, number, and vol- 

 ume (Table 1). Very small hermit crabs 

 (Pagurus spp., Dardanus spp., Paguristes spp., 

 Pylopagurns spp., other Paguroidea) were the 

 dominant decapods in whitebone porgy stom- 

 achs, and they sometimes were found along with 

 their gastropod shells, which were usually very 

 damaged. Gastropods were important prey and 

 sipunculids, especially the species Aspidosiphon 

 gosnoldi which occupies gastropod shells, were 

 frequently consumed. Gastropods and Aspido- 

 siphon sipunculids were often found without 

 their shells. Because mollusk shells were infre- 

 quently swallowed by whitebone porgy, many 

 gastropods and pelecypods could not be identi- 

 fied. The gastropod Costoanachis avara was the 

 most abundant identifiable mollusk in whitebone 

 porgy stomachs. Other important prey for 

 whitebone porgy included polychaetes, pelecy- 

 pods, barnacles, and fishes. 



Table 1. — Percentage of frequency occurrence (F ), percentage of number (/V), and percentage of volume (V) of prey items and 

 higher taxonomic groups of food in the diet of whitebone porgy, Calamus leucosteus. 



Taxon 

 Prey item 



Taxon 

 Prey item 



937 



