POPULATION-DYNAMICS OF JUVENILE CARIBBEAN SPINY LOBSTER, PANULIRUS-ARGUS, IN FLORIDA BAY, FLORIDA

Despite a wealth of information on the growth and population dynamics of sub-adult and adult Caribbean spiny lobsters (Panulirus argus), the re is far less information about younger juveniles under natural condi tions. Here we describe growth and population dynamics of juvenile spi ny lobsters (12-68 mm carapace length, CL) that we have studied for 14 months (October 1988-December 1989) using mark-recapture techniques i n a hardbottom community in Florida Bay, Florida. We also monitored th e supply of postlarvae into the region in 1988 and 1989 using Witham-t ype surface collectors in an effort to link peak periods of settlement of postlarvae with subsequent cohorts of juveniles. Field estimates o f growth were the highest ever reported for this species, averaging 0. 95 mm CL.wk-1 (range: 0.35-1.25 mm CL.wk-1 for individuals 20-25 mm CL and 40-45 mm CL, respectively). These results indicate that lobsters in some areas in Florida Bay can reach Florida's legal harvestable siz e (76 mm CL) 1.5 years after settlement. Season and lobster size had s ignificant effects on growth rates; slower growth occurred during the winter and among small individuals. Differences in growth among size c lasses resulted from changes in molt increment, whereas seasonal diffe rences were a result of changes in intermolt interval. Using mark-reca pture techniques, we estimate that the density of juvenile spiny lobst ers <45 mm CL in this prime nursery habitat was 454.ha-1, that the mea n monthly probability of survival (reflecting actual mortality plus em igration) was 0.51, and that an average of 131 lobsters entered the po pulation through recruitment and immigration each month. Recruitment o f juveniles was significantly correlated (r = 0.83) with the supply of postlarvae to the region 8 months earlier. This relationship is stron ger than was previously believed, and may only be manifested in areas with superior nursery habitat.