Cephalopod species captured by deep- water exploratory trawling in the Northeastern Ionian Sea

Abstract

The search for new fishing grounds in Greek waters, has led to the investigation of unexploited resources on the continental slope of the Northeastern Ionian Sea (Central Mediterranean Sea). Four seasonal experimental surveys were carried out by Greek and Italian commercial trawlers from September 1999 to September 2000, in the framework of the project called "Interregional environmental studies in the Ionian Sea". Potential targets included deep-water species of fishes, crustaceans and cephalopods. During the 4 surveys, a total of 25 species of cephalopods belonging to 10 families were recorded, including 10 oegopsid squids, two myopsid squids, five octopods, two cuttlefishes and six sepiolids. Sepietta oweniana was the most abundant species, followed by Todaropsis eblanae, Illex coindetii and Loligo forbesi. Some uncommon species such as Ancistroteuthis lichtensteini, Ctenopteryx sicula and Galiteuthis armata, were recorded for the first time in the study area. An extension of the depth range was recorded for several species. The results of multivariate analyses, based on Bray-Curtis similarity indices, showed the presence of two associations: one consisting of hauls carried out at depths of 250-500 m, where Sepietta oweniana, Todaropsis eblanae and Loligo forbesi were most frequently caught, and another comprising deeper hauls (up to 800 m depth) characterized by typical species of the slope, such as, Pteroctopus tetracirrhus, Neorossia caroli, Todarodes sagittatus and Abralia veranyi. The number of cephalopod species and the hourly yield decreased with depth and varied with season. The highest mean cephalopod catches per hour (>6kg/hr) were observed in the depth zone 250-500 m in September 1999 and 2000, resulting in a higher percentage (5%) of cephalopods in the total catch. Of the cephalopod species collected, Loligo forbesi, and of the ommastrephid squids, Todaropsis eblanae, Todarodes sagittatus and Illex coindetii, were of commercial interest.