Spatial and temporal patterns of habitat use by fishes associated with Sargassum mats in the northwestern Gulf of Mexico

Distribution and abundance of fishes associated with Sargassum mats in the northwestern Gulf of Mexico were examined off northern (Galveston) and southern (Port Aransas) Texas from May–August, 2000. A total of 36 species (17 families) was identified from larval purse seine collections. Individuals from seven species composed over 97% of the catch: planehead filefish Monacanthus hispidus (Linnaeus, 1766), blue runner Caranx crysos (Mitchill, 1815), gray triggerfish Balistes capriscus (Gmelin, 1789), chain pipefish Syngnathus louisianae (Günther, 1870), sergeant major Abudefduf saxatilis (Linnaeus, 1758), sargassum fish Histrio histrio (Linnaeus, 1758), and greater amberjack Seriola dumerili (Risso, 1810). Sizes were variable throughout the sampling period; however, over 95% of the species collected were in the early life stages. Temporal patterns were observed for several taxa: M. hispidus, S. louisianae, and H. histrio were more abundant in May and June, while C. crysos and A. saxatilis were more common in July and August. Abundance of dominant taxa was higher in northern waters and both abundance and diversity increased as a function of distance from shore. Natural associations of ichthyofauna were observed across zones and region samples, and most of the variation was attributed to sample month. Results of this study suggest pelagic Sargassum serves as nursery habitat and may influence the recruitment success of several species.