Distribution and some aspects of the Biology of Scaeurgus unicirrhus (Cephalopoda : Octopodidae) in the Southern Tyrrhenian Sea (Central Mediterranean)

Distribution, abundance and some aspects of the biology of Scaeurgus unicirrhus are reported in the Southern Tyrrhenian Sea (Central Mediterranean), by integrating data from 14 bottom trawl surveys (1994-2007). The catches of S. unicirrhus showed a wide bathymetric distribution (32-608 m), although the bulk of the catches was observed in the 100-150 m depth range. The spatial distribution highlighted that the species was captured in higher abundance in the western part of Sicily and in the easternmost part of the studied area. Catch data (number and weight) were analyzed, taking into account the surface of each sub-area and depth stratum, in order to obtain estimates of Biomass Index (BI = kg/km2) and Density Index (DI = N/ km2). The temporal evolution of the overall (all strata combined) survey mean DI (N/km2) showed a significant trend (rs = 0.670); while BI (kg/km2) showed a not significant trend (rs = 0.165). Mean length of immature and mature specimens were not different between sexes (p > 0.05). The potential fecundity of maturing and mature females ranged from 263 to 4295 eggs. The relative fecundity was 44.55 egg/g. The number of spermatophores ranged from 12 (50 mm ML) to 29 (45 mm ML).