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Fishery Bulletin 92(3). 1994 



A large fraction of all food eaten by M. amaena 

 and most other Myripristis species appears to be 

 taken from the water column, often at some distance 

 above the substrate. However, relatively little of what 

 we found or of what has been reported in the diets of 

 these species in Hawaii appears to be holoplanktonic. 

 Among the many small crustacean groups identified 

 in the diets, few copepods were found. A number of 

 the common crustacean prey were from groups such 

 as mysids and amphipods that migrate vertically (of- 

 ten on a diel schedule) within shallow water, and may 

 shelter on or near benthic substrate, within caves, 

 cavities, rubble, or other cover during part of the day. 

 Larval and young juvenile forms of larger benthic 

 Crustacea, such as crabs, lobsters, stomatopods, and 

 some shrimp, may be components of this migrating 

 "semiplankton." Some shrimps may be intermittently 

 sedentary or free swimming as adults. What is known 

 of this semiplankton ( Alldredge and King, 1977; Por- 

 ter and Porter, 1977; Parrish, 1989) and of the diet 

 and feeding of Myripristis suggests that these 

 squirrelfishes are not restricted to either planktonic 

 or benthic feeding, but that they consume these prey 

 groups wherever they are accessible. 



The dominance of this semiplanktonic, probably 

 vertically migrating, fauna in the diet of these fishes 

 has important implications for their trophic linkage 

 to the surrounding systems. Whatever the spatial 

 and temporal details of their residence in the water 

 column, the dominant "zooplankton" seem charac- 

 teristic of an inshore aggregation, probably tied 

 closely to shallow water. Therefore, these squirrel- 

 fishes depend for their trophic support largely on lo- 

 cal sources of secondary production and possibly even 

 primary nutrients (Parrish, 1989). This trophic ar- 

 rangement is in contrast to the traditional concept 

 of shallow-water planktivorous fishes supported by 

 holoplankton of open ocean origin brought to the coast 

 by prevailing oceanic currents. 



There are reports of some Myripristis species feed- 

 ing close over the substrate (Brecknock, 1969; ter 

 Kuile, 1989). Hiatt and Strasburg (1960) noted that 

 M. microphthalmus (,=violaceus; Greenfield, 1974) in 

 the Marshall Islands "takes a great variety of crus- 

 taceans which are associated with, or swim near, the 

 coral mounds in which this. ..fish secludes itself." 

 They also found that some of their specimens had 

 eaten tube-dwelling polychaetes — clearly a benthic 



