The deep-water red shrimp, Aristaeomorpha foliacea, of the Sicilian Channel: biology and exploitation
Bianchini, Marco, 1950-
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A research has been carried out the red shrimp, Aristaeomorpha foliacea, resources of the Strait of Sicily (Mediterranean Sea); the study was aimed at assessing the natural history of the local population, at evaluating the specific fishery, and at proposing management interventions. The experiment was based on seasonal trawl surveys and on two selectivity surveys, employing the covered cod-end method. Various methods have been used to estimate the growth parameters (MULTIFAN, MIX, etc.), as well as the mortality coefficients: morphology and reproduction have been studied too. Specific fishery aspects have been addressed, among which yields, diel differences, selectivity, engagement pattern, quali-quantitative composition of the by-catch. The virtual population has been reconstructed, and the subsequent yield-per-recruit analysis has been accomplished on with different methodologies (incomplete beta function, Thompson & Bell, VIT, ANALEN); sensitivity analyses, transitional profiles, variable recruitment and yield scenarios have been performed. The economic yield-per-recruit analysis has been carried out following the same approaches. Fishermen's interviews, exam of logbooks, and other instruments produced an overview of the human factors ruling the fishery. The Y/R estimates suggest a situation of light overfishing; in economic terms, lowering F to the level of the F0.1 strategy will even produce a substantial increase in the present economic Y/R. Gains in the Y/R could not be obtained without changing the age of first capture. A. foliacea in the Sicilian Channel is caught before reaching the maximum reproductive potential; moreover, undersize animals are worthless in economic terms. Raising and enforcing the legal mesh size could control this growth overfishing; in fact, the present legal mesh (20 mm, side) makes no biological or economical sense. The introduction of a 28 mm mesh cod-end would result in the escapement of almost exclusively the juveniles; since these small shrimps are valued sensibly less than large specimens, only a small loss in the immediate economic return should be expected, followed by long-term gains for the shrimp population, the fishermen and the environment.
- Fisheries