A population dynamic study of the south Florida spiny lobster (Panulirus argus) fishery using simulation modelling

The Florida spiny lobster, Panulirus argus, is important to sport and commercial fisheries, being one of the major fisheries in economic yield in the Florida Fishery Conservation Zone (FCZ). Commercial fishing has intensified greatly since the late 1960\u27s as landings may have reached a maximum level and the number of traps used in the fishery climbed over a record 939,000 traps in 1991. Various management regulations have been implemented to deal with overexploitation; however, it is not known how these management actions have affected the existing stock, nor is it known how long the stock can continue to sustain itself with increased fishing pressure.A simulation model of yield and egg per recruit using molt groups was developed to assess the population dynamics of the spiny lobster fishery in south Florida. Parameter estimates of growth, mortality, and reproduction were derived using raw data from various sources and data from the literature. The fishery was simulated as the present fishery using shorts as bait, and as a fishery with escape gaps installed in traps. These simulations were run with growth variability and a range of molt specific and constant natural mortalities, short handling mortalities, and fishing mortalities.Separate simulations were run for each sex, such that harvesting strategies would account for maturity and egg production in females. As sufficient data were not available to properly determine a recruitment component, results were expressed on a per recruit basis. The present fishery using shorts was determined to be more efficient than the gap fishery at fishing mortalities less than 1.6 and is operating at F values greater than needed to obtain maximum yield per recruit. Variable growth produced slight increases in yield and egg per recruit. Increases in size at first capture produced decreases in yield per recruit and increases in percentage of eggs with no exploitation. Reductions in fishing mortality produced increases in yield per recruit and percentage of eggs with no exploitation and fishing at F$\sb{0.1}$ resulted in slight reductions in yield per recruit, but made the fishery more efficient by requiring reduced effort to obtain a yield similar to F$\sb{\rm max}$