Determinación in situ del contacto de redes de arrastre de fondo

Abstract

Tests were carried out in an attempt to determinine the moment at which the trawl gear utilized in demersal crustacean fisheries came into effective contact with the bottom. Results of the determination permit clear definition of effective tow duration, as this is an essential parameter for estimations of abundance carried out by the swept-area method. This paper presents the results obtained using a contact sensor that registers tilt angle of the footrope, permitting continuous monitoring of the net performance on the seafloor. The measurements of the tow duration with the contact sensor are compared with the method typically used, and a discussion is presented of the advantages of the new method for obtaining estimations of abundance.