A Preliminary Investigation of the Efficiency of Canadian and Spanish Survey Bottom Trawls on the Southern Grand Bank

• Main Authors: Walsh, S.J. (Stephen), Paz, X. (Xabier), Durán-Muñoz, P. (Pablo)
• Format: Report
• Language: English
• Published: Centro Oceanográfico de Vigo 2001
• Subjects: Canada; North Atlantic; Northwest Atlantic
• Online Access: http://hdl.handle.net/10508/1573

Preliminary analysis of the capture efficiency of the bottom trawls used by Canada and Spain in surveys of the Grand Bank was conducted using a variant of the logistic model to analyse a series of comparative fishing data. Within the Canadian comparative data of the old and new survey trawls, the new survey trawl was less efficient for larger cod and yellowtail flounder but not so for American plaice. However, there is some uncertainty in capture probability for larger fish because of a sparse catches in the data. The Spanish survey trawl is more efficient than the new Canadian survey trawl because of the use of longer sweep lines, which increase catchability in plaice and yellowtail flounder. The logistic model did not fit the data well, in particular for yellowtail flounder. Further analysis is suggested which may offer more insight into modelling and interpretation of the capture efficiency of these survey trawls.