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Figure 2. — Number of Lagodon rhomboides collected in 

 Apalachee Bay, Fla., from December 1976 to November 1977. 

 Crosses = Fenholloway 11, triangles = Fenholloway 12, dots = 

 Econfina 10, circles = Econfina 12. 



stations were examined. The relative proportions 

 of various food items taken by pinfish of different 

 size classes (for all dates and stations) varied 

 widely with fish size (Figure 3) and cluster 

 analysis showed four distinct ontogenetic trophic 

 groups. The first group was planktivorous and in- 

 cludes only those fish <16 mm SL. The second 

 group (16-35 mm) included fish which took har- 

 pacticoid copepods and amphipods in nearly equal 

 proportions plus small amounts of shrimp post- 

 larvae, invertebrate eggs, and other animals. This 

 group was largely carnivorous. Fish of group three 

 (36-80 mm) were omnivores, taking about 30% of 

 their diet in the form of plant material (mostly 

 microepiphytes) and the rest from the macro- 

 benthic fauna (mainly amphipods, small shrimp, 

 and some harpacticoid copepods). Group four ( >80 

 mm) included mostly adult fish, >1 yr old. At least 

 one-half of the diet was plant material; however, 

 stomach contents offish >100 mm SL were <10% 

 animal matter. A large portion of the plant matter 

 consumed was seagrass, especially S. filiforme. 



Pinfish diet was dependent upon the place of 

 capture as well as size of the fish (Table 2). Al- 

 though a large percentage of the stomachs were 

 empty, the primary food item of pinfish between 1 1 

 and 15 mm SL was calanoid copepods at Fenhollo- 

 way 11, Fenholloway 12, and Econfina 12. Fish of 

 the same size class took a large number of inver- 

 tebrate eggs at the inner stations, Econfina 10 and 

 Fenholloway 11. Harpacticoid copepods and 



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FISHERY BULLETIN: VOL. 78, NO. 2 



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Standard Length (nnnn) 



Figure 3. — Ontogenetic changes in diet of Lagodon rhomboides 

 from Apalachee Bay, Fla. Histograms represent relative propor- 

 tions of major dietary components (dry weight). Dendogram rep- 

 resents cluster analysis of diet similarity among size classes. 

 Codes for the food items are given in Table 1. (See text for 

 explanation of the cluster strategy.) 



amphipods were important food items only at 

 Econfina 10. The percentage of diet made up by 

 calanoid copepods was directly related to the mean 

 calanoid copepod standing crop (number per cubic 

 meter) at a given station and time (r = 0.804, 

 P<0.05) (Figure 4). No significant relationships 

 were found between amphipods consumed by the 

 small pinfish and abundance of amphipods in the 

 field; however, amphipods were consumed by post- 



340 



