Studying the relationship between spatial fish distributions and trawl catches

We propose an approach for studying the relationship between spatial fish distributions and the distribution of numbers in trawl catches. Individual spatial fish distributions are derived from acoustics data collected with a drifting buoy by tracking individual fish. The spatial distribution of these individual fish is then characterised using Generalised Additive Models (GAM). The catch distribution is obtained empirically. A model relating the spatial fish distribution and the catch distribution is then developped. This paper concentrates on the first part of the approach, the identification of the spatial fish distribution from acoustic data, which is illustrated for a demersal example from the Barents sea including mainly cod (Gadus morhua) and haddock (Melanogrammus aeglefinus)