Hábitos alimentarios del pez triglido Prionotus ruscarius (Gilbert & Starks, 1904) durante 1996, en las costas de Jalisco y Colima, México Feeding habits of the triglid fish Prionotus ruscarius (Gilbert & Starks, 1904) during 1996, on the Jalisco and Colima coast, México

The stomach content of the common searobin Prionotus ruscarius is described and analysed in this study. A total of 128 specimens, were captured from the continental shelf of Jalisco and Colima, Mexico, between January and December 1996. Percentages of numeric, gravimetric, frequency of occurrence and index of relative importance (IIR) were calculated for each prey item. Thirty food items were observed in the diet. The index of relative importance (IIR) showed that P. ruscarius mainly prey on penaeids shrimp (45.5%), brachyuran (37.8%) and stomatopods (9.7%). Significant feeding variations were found in different fish body sizes. According to Levins Index, used to determine the trophic spectrum, P. ruscarius had a medium grade of specialization. Penaeid shrimps and brachyurans were observed as secondary food items, based on the feeding index.