Ongrowing of Juvenile Spiny Lobsters, Panulirus Argus (Latreille, 1804) (Decapoda, Palinuridae), in Portable Sea Enclosures

Abstract

AbstractThe spiny lobster catch from Bahia de la Ascensión, a large bay on the central coast of the Mexican Caribbean, is composed mainly of young adults and large juveniles of Panulirus argus. The fishery in this bay is based on artificial shelters called "casitas". A substantial part of the lobsters found beneath the casitas is of sublegal size (minimum size limit ~ 74 mm carapace length, CL). The possibility of ongrowing sublegal juveniles in portable sea enclosures to maximize the harvestable biomass was explored. The enclosures (3 x 3 x 1 m) were installed in shallow depths in the bay. Juveniles taken from nearby casitas were introduced in the enclosures and kept for different periods. Lobsters were fed with live molluscs and fish remains and were provided with suitable shelters. Experiments were conducted in two stages, in 1992 and 1993. Growth in size (CL) and in harvestable biomass (weight of legal-size lobsters) was examined. Maximum growth rates, lower percentages of mortality, and higher increases in harvestable biomass of lobsters were obtained after about 45 days. Confinement periods longer than 45 days resulted in reduced growth and higher mortality. Observations on lobster behaviour showed an increase in aggressive encounters and dominance displays from the third week of captivity onwards, which could be the main cause for the increase in mortality. The alternative of ongrowing sublegal juveniles for short periods (45 days), in conjuction with the casita system, could help increase the unit value of the catch.