Effect of fishing tactics on the standardization of cardinalfish (Epigonus crassicaudus) catch rates in the demersal multispecies fishery off central Chile

TL;DR: In this paper, the authors analyzed the allocation of effective fishing effort and the standardization of cardinalfish catch rates in the multispecies demersal trawl fishery off central Chile.

Abstract: We analyzed the allocation of effective fishing effort and the standardization of cardinalfish (Epigonus crassicaudus) catch rates in the multispecies demersal trawl fishery off central Chile. The period analyzed covered from 1997 to 2004 and included detailed information about fishing hauls. Each haul that contained cardinalfish was assigned into a particular fishing tactic (cluster) by using multivariate analysis of their catch composition. The catch rate standardization was carried out by generalized linear models (GLM). Three fishing tactics were discovered: the first directed effort at cardinalfish, the second at common hake (Merluccius gayi gayi), and the third at Patagonian grenadier (Macruronus magellanicus). Fishing tactic was used as an explanatory variable in the proposed GLM. The fishing tactic effect was one of the most important factors in explaining the variance in the GLM. These results are discussed in the context of how the assignation of a fishing tactic allows unbiased abundance indices to be obtained in this kind of multispecies demersal fishery Se analizo la separacion del esfuerzo de pesca efectivo y la estandarizacion de las tasas de captura de besugo (Epigonus crassicaudus) en la pesqueria multiespecifica de arrastre en Chile central. El periodo analizado correspondio de 1997 a 2004 y comprendio informacion detallada acerca del lance de pesca. Cada lance que contenia besugo en sus registros fue asignado a una tactica de pesca (agrupacion) particular mediante analisis multivariado de la composicion de la captura. La estandarizacion de las tasas de captura se realizo usando modelos lineales generalizados (MLG). Se descubrieron tres tacticas de pesca: una cuyo esfuerzo es dirigido sobre el besugo, otra sobre la merluza comun (Merluccius gayi gayi) y una tercera sobre la merluza de cola (Macruronus magellanicus). La tactica de pesca fue usada como variable explicatoria en el MLG propuesto. La tactica de pesca es uno de los factores que en mayor medida explican la varianza del MLG. Por ultimo, estos resultados son discutidos en el contexto de como la asignacion de una tactica de pesca permitiria obtener indices de abundancia sin sesgos en este tipo de pesquerias demersales multiespecificas.