Fishes of the Western North Atlantic 



197 



the fish grows, this diet is supplemented by gastropods, foraminifera, an occasional 

 ostracod, and annelid worms. The diet of the adult is essentially the same (Linton, 

 11: 440; 12: 353; 4: 395). 



Parasites. The principal parasites are nematodes, cestodes {Scolex polymorphus and 

 Rhynchobothrium sp.), and trematodes (Distomum appendiculatum and Distomum sp.) 

 (jj: 440; 12: 2S2)- 



■-"•■••■■? 



Figure 41. Anchoa hefsetus colonensis, 70 mm TL, 56 mm SL, from Colon, Panama, USNM 1 17664, with 

 pectoral fin enlarged. Drawn by Louella E. Cable. 



Variation. So great is the variation in this species that certain specimens from 

 Colon, Panama, and northward to the Gulf of Mexico were recognized (j: 60, fig. 22) 

 as a subspecies, A. hepsetus colonensis. The greatest divergence is apparent in speci- 

 mens from Colon, Panama, with complete intergradation in specimens on the Gulf 

 coast of the United States. As typical hepsetus occurs through the range of h. colonensis, 

 the latter is not a geographical variant but one that occurs within the range of the 

 typical species. 



The variant, or subspecies colonensis, differs from typical hepsetus in having a some- 

 what deeper and more strongly compressed body, its greatest thickness scarcely ex- 

 ceeding the depth of the caudal peduncle. Its pectoral fin is longer and more pointed, 

 generally extending nearly or quite to the base of the pelvic fin. Its silvery lateral 

 band is narrower, often scarcely exceeding the width of the pupil. 



Commercial Importance. Each year large quantities are marketed as food for man. 

 In 1939 about 21,000 pounds and in 1940 about 29,000 pounds were handled in the 

 New York City markets. It is economically important, however, chiefly as a forage fish. 



