Factors affecting discards by the coastal Spanish North Atlantic trawlers

Abstract

Variations in the total discard in weight were evaluated by Spanish trawler fleet operating in the North Atiantic Spanish coast in 1994. The data used for this study came from observers on board commercial fishing boats in ICES Divisions VIIIe and IXa during normal fishing activity. A total of 493 hauls were analysed and 221 commercial and non-commercial species discarded were determined. The response variable studied is the whole discard of all species per unit effort. A general analysis of covariance was carried out with the following sources of variation: trip, quarter, area, port, three types of gears, groups of boats (using multivariant analysis of classification) and as covariables: total eatch per unit effort, fishing hours, depth, tonnage, horsepower and length of the boats studied. The results show a great variation in the discard values by unit of effort for this fleet, except for the intra-annual variation.