FISHERY BULLETIN: VOL. 86, NO. 3 



P. notialis, 87% of all P. subtilis, and 78% of all 

 P. brasiliensis contained food. At least 50% of all 

 animals in any one size class contained food on a 

 given sampling date, but no seasonal or ontogenetic 

 pattern in empty guts w&s evident. 



The primary dietary components of all three 

 penaeids were amphipods, polychaetes, harpacticoid 

 copepods, and detritus (Fig. 2). For all species in- 

 crease in shrimp size was correlated with decrease 

 in the relative importance of harpacticoid copepods 

 in the guts. Other small taxa such as nematodes and 

 foraminifera also decreased with shrimp size. Detri- 

 tal components of the diets remained relatively con- 

 stant at approximately 20 to 25% of the gut con- 

 tents. Abundance of polychaetes and amphipods 

 changed relatively little with size in P. notialis and 

 P. subtilis, except that amphipods increased in im- 

 portance with size in P. subtilis and large quantities 



of amphipods were taken by the largest size class. 

 Cluster analyses for the diets of individual species 

 revealed little ontogenetic variation for these two 

 species, except with the distinct separation of the 

 largest P. subtilis (Fig. 2). For both P. notialis and 

 P. subtilis, all size classes between 7 and 22 mm CL 

 were clustered within similarity indices of 0.78. 

 Although only three size classes were represented 

 for P. brasiliensis, ontogenetic variation in P. 

 brasiliensis was greater than in the other two 

 species (Fig. 2). Polychaete consumption decreased 

 from 47% of the diet in the 7 to 10 mm class to 22% 

 in the 15 to 18 mm class, while amphipod consump- 

 tion increased from to 61%. Detritus consumption 

 also decreased with size in P. brasiliensis, contrib- 

 uting to the low similarity indices among the size 

 classes. 

 Four major clusters of shrimp feeding types were 



Penaeus juvenile 



3-6 | AM I PO 



HC 



I 



DE 



^(235) 



10 20 30 40 50 60 70 80 90 100 



E 



E, 



X 



I- 



(3 

 LU 



LD 

 O 

 < 

 CL 

 < 



< 



o 



7-10 

 11-14 

 15-18 



Penaeus notialis 



(206) 



(215) 



(50) 



(8) 



10 20 30 40 50 60 70 80 90 100 



J- 



X 



J- 



1.0 0.9 0.8 0.7 0.6 0.5 0.4 0.3 



Penaeus subtilis 



10 20 30 40 50 60 70 80 90 100 



1.0 0.9 0.8 0.7 0.6 0.5 0.4 0.3 



Penaeus brasiliensis 



PO 



AM 



HC 



DE 



PO 



AM 



HC 



009) 



DE 



PO 



DE 



(82) 

 ](21) 



10 20 30 40 50 60 70 80 90 100 



X 



X 



X 



J 



1.0 0.9 0.8 0.7 0.6 0.5 0.4 0.3 



PERCENT OF DIET 



(N) 



SIMILARITY 



Figure 2.— Diets of the three dominant Penaeus species in Laguna Joyuda, Puerto Rico, shown as a function 

 of shrimp size. Food categories are identified in Table 2. The similarity index used in the cluster diagrams is 

 Czekanowski's coefficient. 



546 



