A multivariate statistical analysis to determine catch intention in the pink cusk-eel (<em>Genypterus blacodes</em>) longline fishery in southern Chile

Rodrigo Wiff; Guillermo Martin Gonzalez; Francisco Contreras; Marcelo A. San Martín; T. Mariella Canales

doi:10.3989/scimar.04953.30A

Authors

Rodrigo Wiff Centre of Applied Ecology and Sustainability, Pontificia Universidad Católica de Chile https://orcid.org/0000-0001-7330-4206
Guillermo Martin Gonzalez Marine Institute https://orcid.org/0000-0002-1984-6140
Francisco Contreras División de Investigación Pesquera, Instituto de Fomento Pesquero (IFOP) https://orcid.org/0000-0003-3062-5477
Marcelo A. San Martín División de Investigación Pesquera, Instituto de Fomento Pesquero (IFOP) https://orcid.org/0000-0003-4284-6322
T. Mariella Canales Centre of Applied Ecology and Sustainability, Pontificia Universidad Católica de Chile https://orcid.org/0000-0003-3238-5825

DOI:

https://doi.org/10.3989/scimar.04953.30A

Keywords:

by-catch, CPUE, catch intention, catch composition, fishing tactics, multivariate analysis

Abstract

The definition of catch intention in multispecies fisheries is a key step toward building abundance indexes based on commercial fishing data. Previous analysis to determine catch intention in the pink cusk-eel (Genypterus blacodes) has been based on the idea that fishing tactics remain constant over time (static fishing tactics). We propose a statistical procedure to determine the catch intention of each haul in the industrial longline fisheries in southern Chile, where fishing tactics may vary over time. This procedure is based on principal component analysis and agglomerative hierarchical analysis of the catch composition, and relaxes the assumption of static fishing tactics by selecting a subset of data that is informative for fishing intention (target versus by-catch) every year. Sensitivity analyses were conducted to assess the robustness of variable fishing tactics on the nominal catch rates in pink cusk-eel. Targeted and by-catch time series of nominal catch rates showed a different trend, so determining the catch intention became relevant. Sensitivity analyses showed that trends in targeted catch rates are robust to the variations of fishing tactic per year. We recommend the use of variable fishing tactics for further use in effort standardization and stock assessment of the pink cusk-eel fishery in southern Chile.

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