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Using information on catch per unit effort, size, and age structure, a suite of quantitative tools were employed to detect trends, and model the dynamics of the spiny lobster, Panulirus argus, resource in Banco Chinchorro without assuming that equilibrium conditions apply. A multiseasonal depletion model was fitted to monthly catch rate (CPUE) data, with catch in numbers and effort measured as fishing trips, for five successive seasons 1988-1989 to 1992-1993. The depletion model captured seasonal and interannual variations of catch rates and provided point estimates of recruitment per fishing season from 43,870-241,150 individuals. The model considered two month-specific values of the catchability coefficient q, whether or not a month showed peaks in catch rate. Monthly fishing mortality rates F were also derived, and F-values per fishing season varied from 0.30-0.38 season-1. These estimates were consistent with those obtained for age-based methods; conversely, they were quite different from those previously estimated by methods assuming equilibrium conditions. Data on commercial size grades were available for two pairs of consecutive fishing seasons, 1983-1984, 1984-1985 and 1989-1990, 1990-1991. Mean recruitment length to the fishery has declined between 1983-1991. Age-based methods with growth parameters for Cuban lobsters provided total (Z) and by-fishing (F) mortality rates, which also declined over the same period, assuming a constant natural mortality rate (M) applies. Overall, this study suggests that fishing effort and fishing mortality must be maintained at levels closer to those applied in the period 1988-1993. A current issue in population dynamics, namely, open versus closed populations, and their consequences for management and for further research are discussed. Inglés

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