Ontogeny of prey selection by black surfperch Embiotoca jacksoni (Pisces: Embiotocidae): the roles of fish morphology, foraging behavior, and patch selection

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Abstract
Proximate mechanisms leading to similarities and differences in diets of juvenile and adult black surfperch E. jackonsi in populations of Santa Catalina Island (USA) were explored. These fish are microcarnivorous, harvesting invertebrate prey primarily from benthic turf and foliose algae. Ontogenetic differences in prey size ultimately reflect age-specific differences in fish size. Young juveniles are apparently gape limited and use a visual picking mode of foraging. This strongly influences the array of algal substrates from which prey can be effectively harvested. Turf substrates are used extensively by older fish that employ winnowing behavior to separate prey from debris. The ability to winnow develops slowly during the 1st year of life and allows explolitation of turf, a prey-rich, extensive resource base. The marked differences in body size aned foraging behavior have only a relatively small influence on the gross taxonomic makeup of the diets of black surfperch.