Mangroves as Nursery Grounds for Recreational Fisheries [Final Report]

Boulon, Ralf

Mangrove lagoon areas on st. Thomas and st. John, u.s.Virgin Islands have been sampled on a monthly basis to assess habitat use and nursery importance for fish and important invertebrates. Three study sites of varying degrees of degradation were chosen for study. Visual censuses and standardized trapping have been conducted along the mangrove shoreline, counting all individuals of each species observed or trapped and recording total and standard (trap fish) lengths. The Mangrove Lagoon, St. Thomas site has a small fringe of red mangrove which is moderately to severely degraded. The Hurricane Hole, st. John site represents the "natural" conditions. Results have demonstrated a significant difference in species diversity, species composition and abundance of fishes between the degraded and natural sites. These differences appear to be directly attributable to degree of pollution. The Vessup Bay site is similar to the middle zone of the Mangrove Lagoon, due as well to impacts from sewage outfall and densely moored boats. Primary differences between sites appear to be related more to water quality than to structural complexity of the substrate. Both visual censuses and trapping have provided indications of annual recruitment cycles into the nursery habitat (eg. Sphyraena barracuda,Ocyurus chrysurus) and nursery value to important coral reef species.