Loligo forbesi and Ommastrephid squids by-catches on the north-eastern Ionian Slope: preliminary analysis of stock structure based on exploratory trawling

Four trawl surveys were carried out on the slope of the North-eastern Ionian Sea, from September 1999 to September 2000, in the framework of the project “Interregional environmental studies in the Ionian Sea (INTERREG II)”. The bottom area investigated was subdivided into four depth strata: 300-500, 500-700, 700-900 and 900-1200 m; and the sampling was based on random-stratified design. Between the cephalopod species collected during exploratory trawling, Loligo forbesi and Ommastrephid squids were those with the greatest commercial potential. A first analysis of the resource is presented here. Stratified CPUE indices showed that Loligo forbesi, Todarodes sagittatus, Todaropsis eblanae and Illex coindetii constituted the major part (>70%) of cephalopod catches between 300 and 700 m during autumn and spring, but was quite lower in summer due to the scarcity of ommastrephids in the catches. L. forbesi was constantly present in the stratum 300-500 m throughout the year, dominated by immature individuals. Among the two short-fined squids, the proportion of I. coindetii was higher in both autumns whereas T. eblanae was more abundant in spring. Their low catches in July are probably related with the high post-spawning mortality of these species. No seasonal trend could be defined in the catches of the pelagic T. sagittatus. The occurrence of fully mature males in the study area, indicates probable spawning locations of the species

A pilot experiment of tagging the deep shrimp <i>Aristeus antennatus</i> (Risso, 1816)

A tagging experiment of the blue and red shrimp, Aristeus antennatus was carried out in the Ionian Sea, off Roccella Jonica (RC). The experiment involved 45 shrimps, caught by trawling at night at about 100-150 m in depth. One month after tagging one specimen was recaptured at about 10 nautical miles from the releasing point. As the first case of tagged recaptured deep sea shrimp, this experiment brings important results about the feasibility of experimental studies on displacement and growth and gives the first direct proof of the migratory abilities A. antennatus