-Bycatch of several groups of species and their characteristics are presented for the period 2003 to 2007 for the European purse seine tuna fishery operating in the Atlantic Ocean. Data were collected through French and Spanish observer programmes and represented a total of 27 trips corresponding to 2.9% coverage. Bycatch is defined as nontargeted species and small or damaged target species. Bycatch species composition, main species length, sex ratio and the fate of the most common species are presented first. Stratified ratios relative to landings of major commercial tunas were then used to estimate the total bycatch; these ratios were considered the most appropriate variable for extrapolation. Stratification was based on the fishing mode (free school vs. floating object), season (quarters) and spatial areas. The annual average bycatch was estimated at about 6400 t, corresponding to a mean annual value of 80.8 t per 1000 t of tuna landed or 7.5% of the total catch. Tunas represent 83% (67.2 t/1000 t) of the total bycatch, followed by other bony fishes (10%, 7.8 t/1000 t), billfishes (5%, 4.0 t/1000 t), sharks (1%, 0.9 t/1000 t) and rays (1%, 0.9 t/1000 t). Based on estimates of the annual bycatch, 16% was kept on board and sold in local markets.Key words: Bycatch / Discards / Tuna fisheries / Purse seining / Atlantic Ocean Résumé -Les quantités de captures accessoires de plusieurs groupes d'espèces ainsi que leurs caractéristiques sont présentées pour la pêcherie thonière européenne à la seine opérant dans l'océan Atlantique pour la période [2003][2004][2005][2006][2007]. Les données ont été collectées lors de programmes d'observateurs embarqués français et espagnols représentant un total de 27 marées soit un taux de couverture de 2,9 % des marées totales. Les captures accessoires sont définies ici comme les espèces non ciblées ainsi que les individus petits ou abîmés des espèces-cibles. La composition spécifique des captures accessoires, la structure de taille des principales espèces, le sex-ratio et le devenir des espèces les plus communes sont présentés. La méthode des ratios par rapport aux débarquements d'espèces commerciales est ensuite utilisée pour estimer la quantité totale de capture accessoire. Ces ratios ont été considérés comme la variable la plus appropriée pour l'extrapolation. Une stratification a été utilisée, basée sur le mode de pêche (pêche sur banc libre versus pêche sur objet flottant), le trimestre et les zones spatiales. La quantité de capture accessoire annuelle moyenne est estimée à 6400 t, correspondant à une valeur annuelle moyenne de 80,8 t par 1000 t de thons commercialisés ou 7,5 % de la capture totale. Les thons représentent 83 % (67,2 t/1000 t) du total des captures accessoires suivis par les autres poissons osseux (10 % ; 7,8 t/1000 t), les poissons porte-épées (5 % ; 4,0 t/1000 t), les requins (1 % ; 0,9 t/1000 t) et les raies (1 % ; 0,9 t/1000 t). On estime que 16 % de ces captures accessoires est conservé à bord et vendu sur le marché local.

Amandè, M. J., Chassot, E., Chavance, P., Murua, H., Delgado de Molina, A., and Bez, N. 2012. Precision in bycatch estimates: the case of tuna purse-seine fisheries in the Indian Ocean. – ICES Journal of Marine Science, 69: . Estimating bycatch, i.e. the incidental catch of non-target marine animals and undersized individuals of target species, by raising observer data to the whole fishery is routine practice. The annual bycatch of the European tropical tuna purse-seine fishery over the period 2003–2009 was estimated at 11 590 t [95% confidence interval: (8165–15 818 t)], corresponding to 4.7% of the tuna landings. An analysis of the variability in the precision of this estimate, based on generalized linear models and Monte Carlo simulations, showed that the current sampling coverage of the tropical tuna fishery observer programme, which is 4.6% of the fishing trips, resulted in large uncertainties in bycatch estimates by species, i.e. none of the estimates have a relative root mean square error smaller than 50%. Although the overall magnitude of bycatch of the fishery appeared to be small, the current sampling coverage was insufficient to give any reliable estimate for low-occurring species, such as marine turtles, some oceanic pelagic sharks, and some billfishes. Increasing the sampling coverage would likely improve bycatch estimates. Simulation outputs were produced to help define (i) trade-offs between the priority species to be monitored, (ii) the estimation precision, (iii) expected accuracy, and (iv) the associated sampling costs.

-Ecological risk assessment is a useful methodology for assisting the management of fisheries from an ecosystem perspective. Atlantic tuna fisheries, managed by the International Commission for the Conservation of Atlantic Tunas (ICCAT), are economically important and interact with several bycatch species. In spite of these interactions, no comprehensive ecological risk assessment has been conducted for bycatch species caught in ICCAT fisheries. In this paper, we followed a two stage approach with the objective of assessing the relative risk of species being negatively impacted by Atlantic tuna fisheries. An analysis of the ICCAT bycatch species list (which includes all species reported to have interacted with different tuna fishing gears operating in the Atlantic) revealed that most of these species are caught in longline fisheries, followed by gillnets and purse seines. According to the IUCN red list, 7 species of the ICCAT bycatch list (3 coastal sharks, 3 sea turtles and one seabird) are categorized as critically endangered. In our study, and based on their life history characteristics, marine mammals and coastal sharks caught in ICCAT fisheries showed the highest intrinsic vulnerability values. A productivity susceptibility analysis for the European Union (EU) tropical tuna purse seine fleet and the United States (US) pelagic longline fleet revealed two groups with high relative risk scores. The first one included pelagic and coastal sharks, characterized by relatively low productivities, and the second one included teleosts, characterized by higher productivities but high susceptibility to purse seine and longline gears. Some alternative approaches to conduct productivity susceptibility analyses in the context of ecological risk assessments are discussed.