Abstract

Information on the pelagic distribution of phyllosoma larvae is of relevance for fisheries and recruitment research, specially for palinurids which have an extended planktonic life cycle estimated to last 6 - 12 months. The objective of this study was to examine the taxonomic composition of phyllosoma larvae in the south-west coast of Puerto Rico and to determine their distribution along an inshore-offshore gradient. Lobster phyllosoma larvae were sampled during three cruises in February, August and December, 1995 and May, 1996 to examine temporal, spatial and ontogenetic distribution patterns across an inshore-offshore gradient off La Parguera. Samples were taken at six different distances across the inshore-offshore gradient (6, 10, 13, 16,29 and 46 km from the coastline) along three parallel transects (67°00’, 67°03’ and 67° 06’ W) for a total of 18 stations. Samples were collected in stratified step-oblique tows at three discrete depths (0 -20 m; 21-40 m; 41 60 m) using a 1 m2 Tucker Trawl system fitted with three 0.202 mm mesh. A total of 594 phyllosoma larvae were collected. Fifty eight percent of the total larvae were collected in May, with maximum abundance at the innermost station (6 km). Larvae were identified into three genera (Panulirus, Scyllarides and Scyllarus) of which Panulirus was the most abundant (69%) followed by Scyllarides (26%) and Scyllarus (5%). The horizontal distribution of Panulirus showed that early stage larvae (I-III) remained within insular shelf stations, whereas later stage larvae increasesd offshore, thus suggesting an ontogenetic related flux. Scyllarus larvae of all developmental stages were found almost exclusively within the insular shelf. Temporal trends of Panulirus larval abundance between cruises showed that early stage larvae were present year-round but were most abundant during May. This finding supports previous observations that the peak reproductive season in the Caribbean occurs during spring and early fall, but reproduction is continuous in lower itensity throughout the year. Such data suggests that locally spawned larvae of Panulirus and Scyllarides are being transported offshore, whereas Scyllarus larvae appears to be retained in coastal waters during their shorter planktonic life cycle.

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