Diet of <i>Agonostomus monticola</i> (Pisces: Mugilidae) in the Río Ayuquila, Sierra de Manantlán Biosphel'c Reserve, México

Abstract

We quantified the diet of Agonostomus monticola during the wet and dry seasons o f 1990 in a 15 km reach o f the Río Ayuquila, a Pacific tributary o f west-central México. The species consumed 32 animal and 9 plant families, with aquatic insects (mainly Diptera, Ephemeroptera, and Trichoptera) and algae (mainly Chlorophyta) as primary prey. Animal material dominated the diet in the wet season but was only slightly more important than plant material in the dry season. Animal material increased in importance with fish size for specimens 151-300 mm total length. Río Ayuquila A. monticola ate fewer shrimp, Odonate insects, fish, and froit than other studied populations. The broad diet of A. monticola suggests that it is an opportunistic feeder