Assessing the response of exploited marine populations in a context of rapid climate change: the case of blackspot seabream from the Strait of Gibraltar

J C Báez,R Real,L Gimeno,D Macías,M De Castro,M Gómez-Gesteira

doi:10.32800/abc.2014.37.0035

Abstract

There is a growing concern over the decline of fisheries and the possibility of the decline becoming worse due to climate change. Studies on small–scale fisheries could help to improve our understanding of the effect of climate on the ecology of exploited stocks. The Strait of Gibraltar is an important fishery ground for artisanal fleets. In this area, blackspot seabream (Pagellus bogaraveo) is the main species targeted by artisanal fisheries in view of its relevance in landed weight. The aims of this study were to explore the possible effects of two atmospheric oscillations, the North Atlantic Oscillation (NAO) and the Arctic Oscillation (AO), on the capture of blackspot seabream in the Strait of Gibraltar, to determine their association with oceanographic conditions, and to improve our knowledge about the possible effects of climate change on fisheries ecology so that fishery management can be improved. We used two types of data from different sources: (i) landings per unit of effort reported from a second working group between Morocco and Spain on Pagellus bogaraveo in the Gibraltar Strait area, for the period 1983–2011, and (ii) the recorded blackspot seabream landings obtained from the annual fisheries statistics published by the Junta de Andalucía (Andalusian Regional Government). Our results indicate that the long–term landing of blackspot seabream in the Strait of Gibraltar is closely associated with atmospheric oscillations. Thus, prolonged periods of positive trends in the NAO and AO could favour high fishery yields. In contrast, negative trends in NAO and AO could drastically reduce yield.

Highlights

Fisheries are an important source of food and income for many local communities, and their value as a source of animal protein was recently emphasized in a Food and Agriculture Organization report (FAO, 2010)
We evaluated the discrimination capacity of our model using the area under the receiving operating characteristic (ROC) curve (AUC) (Lobo et al, 2008)
A significant association was found between the Landings Per Unit of Effort (LPUE) of blackspot seabream from the Gulf of Cadiz and the NAO in the previous year (NAOpy) index, according to the following function: LPUE = 66.687 + 15.01 NAOpy

Summary

Introduction

Fisheries are an important source of food and income for many local communities, and their value as a source of animal protein was recently emphasized in a Food and Agriculture Organization report (FAO, 2010). The observed decline in fisheries is mainly due to overfishing at an industrial scale (Worm & Myers, 2004; Pitcher, 2005). This situation could be aggravated by the response of fish populations to cli mate change (e.g. see Brandt & Kronbak, 2010). With the aim of integrating fisheries within sustainable ecosystems, Pitcher (2005) proposed studying the ef fect of climate parameters and their temporal variability on global fisheries. Some fisheries have been shown to respond to multi–decadal oscillations, such as the oscillation of El Viejo (The Old Man), or La Vieja (The Old Woman), in the Pacific (Chavez et al, 2003), and decadal oscillations, such as the North Atlantic Oscilla tion (Báez et al, 2011; Báez & Real, 2011)

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