Analisi preliminare del comportamento di due reti a strascico utilizzate nelle campagne di pesca "GRUND"

In the last decades, varius trawl surveys were carried out all along the Italian coasts by using the local commercial nets. The gear performances of two commercial nets were monitored by means of acoustic equipment for more than 170 hauls. The mouth horizontal opening doubles with depth from 10 m to 600 m. while the vertical opening remains almost costant. Fishing speed changes in relation to vessel power, and it is always lower at higher depths. Morover the descendent time can vary from 5 min to more than 30 min and can bias the biomass estimates at greater depths.