Abstract

Early stages of juvenile Centropomus spp., a group of economically important species, were surveyed in Puerto Rico estuarine areas. Sampling was conducted from April `92 to December `93 Habitat included shallow fresh water areas (<3m), such as river banks and tributaries (marsh, water hyacinths), and in brackish to salt water areas, such as lagoons and backwaters (red and black mangrove).\Five species of snook were collected : Centropomus undecimalis, C. ensiferus, C. parallelus, C. mexicanus and C. pectinatus. The distribution of the 5 species varied among habitat sampled. Early juvenile snook (SL<50mm) in river systems were largely dominated by C. parallelus (75%); and in lagoon systems, by C. undecimalis (60%) and C. ensiferus (35%). Colonization peaks of the 3 dominant species show broad overlapping : from June to November for C. undecimalis, from April to December for C. parallelus and from June to August and December to January for C. ensiferus.\Preferred nursery habitats are very turbid and calm waters, in the vicinity of shelter (mangrove roots, grass, or water hyacinths). The physical parameter range of juvenile snook habitat is relatively broad : salinity from 0 to 30, temperature from 24° to 35°C, anoxic to high oxygenated water. Condition factors of fish < 100mm SL showed no significant difference (non parametric test of Kruskal-Wallis) between river and lagoon systems. Although their food habits were similar during early stages (SL<100mm), food does not seem to be a limiting factor among the different systems.

PDF Preview