Growth discontinuity in males of the deep-water giant red shrimp Aristaeomorpha foliacea in the Mediterranean Sea

摘要: The deep-water giant red shrimp, Aristaeomorpha foliacea (Risso, 1827) (Decapoda, Aristeidae), represents a highly valuable resource for bottom trawling in the Mediterranean Sea. Recent assessments have described both worsening of status traditionally exploited stocks and low levels annual-based instantaneous natural mortality (M 0.4–0.7 year−1) unexploited stocks. (M) figures, however, are contrast with longevity (Tmax) 3–4-year males 4–5-year females, estimated from classical length frequency distribution analysis. Reduced growth (after onset sexual maturity) pile-up older individuals larger size classes been considered to be reasonable explanations between M Tmax. We propose that discontinuity models could address this contrast. Because clear maturity is evident only males, data different sets collected South Sicily Maltese Islands deep bottoms (400–800 m) were fitted classic (c) double-phased (d) von Bertalanffy formula (VBGF). According dVBGF, adult sharply reduce their rate after reaching an age 1.2 1.5 year, which corresponds estimates at (tm 1 1.5 years). reduction determines higher Tmax (7.3–9.5 year) lower (0.4–0.6 year−1) than previously derived on basis cVBGF (Tmax 3–4 years 1.2 year−1). dVBGF results suggest dimorphism length–sex segregation shrimps reflect alternative life history strategy based mainly it might adopted implementing more conservative assessments.