FISHERY BULLETIN: VOL. 78, NO. 2 



Table 3. — Abundance of prey organisms and biomass of benthic macrophytes' in Apalachee Bay, Fla., from December 1976 to 

 November 1977. Only epifaunal species commonly consumed by Lagodon rhomboides were included in the abundance of amphipods. 



' Macrophyte data were provided by R. J. Livingston (see text footnote 2). 



This point will be discussed later. Polychaetes, 

 bivalves, amphipods, and other taxa were con- 

 sumed by adult pinfish where macrophyte cover 

 was low. 



Seventy percent of the postlarval pinfish from 

 Fenholloway stations were empty and 42.8% of 

 the fish from Econfina stations had no stomach 

 contents (Table 2). Empty stomachs in pinfish > 15 

 mm SL were less common than found in postlarval 

 fish, but fish collected at the unvegetated site con- 

 sistently had the highest percentage of empty 

 stomachs. Between 11.5 and 15.3% of adult fish 

 taken from vegetated sites had empty stomachs, 

 but 30% of the adults from Fenholloway 11 were 

 empty. 



Ontogenetic and spatial variations in pinfish 

 diet were interrelated with changes in diet with 

 season. Overall diet of the pinfish population at a 

 given station was highly dependent upon the 

 length-frequency composition of the population 

 (Figure 5); therefore, to examine independently 

 the effect of season on food habits, size was held 

 constant. Individual size groups, based on the 

 cluster analysis of feeding ontogeny (Figure 3) 

 were tested for seasonality in diet. Although the 

 mean length offish in the 16-35 mm SL size class 

 increased from 20 to 32 mm between March and 

 August, an analysis of dietary changes within 5 

 and 10 mm size classes indicated that the bias was 

 not serious and that the change in food habits over 

 time within the larger size group was an accurate 

 representation of dietary seasonality. Length-fre- 







Q. 

 E 



40 

 20 



20 - 



40 

 20 



20 

 40 

 20 

 40 

 20 

 40 

 20 



40 

 20 

 40 

 20 

 40 

 20 



20 



20 h 



Dec 

 J an 



Feb 



Mar 

 Apr 



May 



J une 



July 

 Aug 



Sept 

 Oct 



20 40 60 80 100 120 140 160 



Standard Length (mnn) 



Figure 5. — Length-frequency distributions for Lagodon rhom- 

 boides collected in Apalachee Bay, Fla., from December 1976 

 to November 1977. Dots indicate that <3.09c of the sample oc- 

 curred in the size class. 



342 



