Caratteristiche qualitative ed indici somatici di specie ittiche di interesse commerciale e monitoraggio dell’attività di pesca a circuizione nel mare della Sardegna nord-occidentale

This dissertation is composed of three experimental chapters and it is focused on the evaluation of qualitative characteristics and somatic indices of some major commercial fish and on the monitoring of purse seine fishing activity in the North West Sardinian Sea. In the first chapter the population consistency of the target specie (S. pilchardus) has been evaluated during the year 2010 purse seine fishing season in the NW Sardinian Sea. The results have been compared with those published in 2005 (year 2003 fishing season) and 2008 (year 2007 fishing season) and the variations of some characteristic chemical-nutritional factors of fish sampled in the Sardinian Sea have been evaluated during the fishing season. In the second chapter a comparison (chemical and morphometric) have been made between two different species of Mediterranean mullet of high commercial interest, the surmullet (Mullus surmuletus) and the red mullet (Mullus barbatus) with the West African goatfish (Pseudupeneus prayensis). The third chapter is centered on the determination of Selenium content and toxicity in several species of mugilides. At the beginning the Selenium level in wild mugilidae species, caught in costal lagoon of Sardinia, has been determined. Subsequently, one trial has been carried out to test the Selenium tendency to accumulate in flesh and organs and its influence on growing performances of small mugilidae (Liza aurata) reared in tank and fed with scalar amount of Selenium in the diet.