The feeding habits of spotted sand bass (Paralabrax maculatofasciatus) in Punta Banda Estuary, Ensenada, Baja California, Mexico

The feeding habits of spotted sand bass (Paralabrax maculatofasciatus) and their seasonal changes are described for the Punta Banda Estuary, Baja Cali fornia (B.C.). Samples were collected monthly from April 1992 to March 1993 , yielding 92 specimens ranging from 80 to 330 mm standard length. In the e ntire survey, decapods, fish, and mollusks were the major food items of spo tted sand bass, with total indexes of relative importance (IRI) of 37.2% (1 ,828), 32.0% (1,572), and 13.4% (658), respectively. Prey groups with high numeric importance were eggs of topsmelt (Atherinops affinis) and gammarids . In summer; the decapods had the highest IRI value (6,234), representing 5 8.4% of total IRI; followed by gammarids (2,255), 21.1% of total; and mollu sks (1,234)1 11.5% of total. In winter, fishes were the most important item , with 42.3% (1,964) of total IRI, followed by decapods (910), 21.9% of tot al. Other seasonal changes were the variation in the numeric importance of gammarids (major in summer, minor in winter) and topsmelt eggs (absent in s ummer, high in winter). The difference in spotted sand bass dirt and its se asonal changes probably reflect differences in available prey and the troph ic flexibility of the species. The diet of spotted rand bass indicates fora ging close to the substrate, frequently in seagrass beds, as indicated by t he high occurrence of eel-grass (Zostera marina) fragments in gut contents.