Identifying mature fish aggregation areas during spawning season

By Yvonne Sadovy
October 05, 2023

Determining and safeguarding crucial fish habitats such as spawning grounds necessitates a thorough understanding of fish distribution both spatially and temporally. Combining commercial declarations with Vessel Monitoring System data yields detailed insights throughout the year, aiding in mapping fish distribution and pinpointing essential habitats. We formulated an integrated approach to deduce fish spatial distribution on a monthly basis by amalgamating scientific and commercial data, while distinctly acknowledging the fishermen’s inclination towards areas with higher biomass. We devised a technique to pinpoint areas with consistent biomass aggregation during the spawning season, interpreting these as spawning grounds. This model is employed to generate maps of relative biomass for three species (sole, whiting, and squids) in the Bay of Biscay, assessed monthly over a span of nine years. The inclusion of various fleets in the analysis enhances area coverage and refines model predictions. The parameters for preferential sampling offer a glimpse into the temporal dynamics of the targeting behavior across different fleets. Lastly, the identified persistent aggregation areas align with existing literature on spawning grounds, underlining the potential of our methodology in recognizing reproductive areas.

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