Dear Fish-Ecologist:

At present we are studing the fish demersal communities of the Gulf of 
Salamanca (Northestearn Colombian Caribbean Sea). For this purpose, 
demersal biomass densities are calculed using the "Swept Area" method by 
stratum. The question is: Does anybody know what are the most appropriate 
"q" value (catchability coefficient) if we use a scientific trawl (mesh 
size 4 cm) and each tow has a standard duration of 30 min?

Thanks in advance.

Luis Orlando Duarte C.
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Proyecto Ecología Pesquera
INVEMAR - Marine and Coastal Institute
A.A. 1016 Santa Marta, Colombia S.A.