History and dynamics of the overexploitation of the blackspot sea bream (Pagellus bogaraveo) in the Bay of Biscay

Abstract

Abstract Lorance, P. 2011. History and dynamics of the overexploitation of the blackspot sea bream (Pagellus bogaraveo) in the Bay of Biscay. – ICES Journal of Marine Science, 68: 290–301. The blackspot sea bream (Pagellus bogaraveo) used to be a major species in the landings from the Bay of Biscay up to the early 1980s. Nowadays, it is only a minor bycatch. Up to the mid-1970s, more than 15 000 t of blackspot sea bream were landed annually in Spanish and French ports. Thereafter, catches declined sharply from 1975 to 1985 and have stayed at low levels ever since. Here, the full history of the fishery collapse is described, using time-series of landings dating back to the early 1900s. Fishing mortalities of the main demersal stocks (hake, anglerfish, sole) were in the range 0.2–0.5 during the last 30 years. It is likely that the blackspot sea bream stock was exploited at a similar level, which is shown here to be unsustainable. The blackspot sea bream is highly sensitive to overfishing because of its protandrous hermaphroditism, with late first maturity (8 years) as females and rather low productivity. According to a yield-per-recruit model, the biomass of fecund females (BFF) is reduced to <20% of virgin BFF for a fishing mortality around 0.2. A dynamic model assuming a simple stock–recruitment relationship fitted to the reconstructed landings explained the collapse, with estimated fishing mortalities never exceeding 0.5.