Bycatch of the European purse seine tuna fishery in the Atlantic Ocean for the 2003-2007 period

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 non-targeted 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.

[1]  Y. Ye,et al.  Bycatch and discards of the Kuwait shrimp fishery , 2000 .

[2]  David Fletcher,et al.  Modelling skewed data with many zeros: A simple approach combining ordinary and logistic regression , 2005, Environmental and Ecological Statistics.

[3]  A. Zuur,et al.  Choosing the best sampling unit and auxiliary variable for discards estimations , 2005 .

[4]  S. Garcia.  The ecosystem approach to fisheries : issues, terminology, principles, institutional foundations, implementation and outlook , 2003 .

[5]  D. L. Alverson.  A global assessment of fisheries bycatch and discards , 1994 .

[6]  H. Murua,et al.  Optimum sample number for estimating shark by-catch in the Spanish Purse Seiners in the Western Indian Ocean , 2007 .

[7]  J. Stretta,et al.  Les espèces associées aux pêches thonières tropicales dans l'océan Indien , 1998 .

[8]  R. Pianet,et al.  NEW SAMPLING AN D DATA PROCESSING STRATEGY FOR ESTIMATING THE COMPOSITION OF CATCHES BY SPECIES AND SIZES IN THE EUROPEAN PURSE SEINE TROPICAL TUNA FISHERIES , 2000 .

[9]  Alain Fonteneau,et al.  A worldwide review of purse seine fisheries on FADs , 2000 .

[10]  E. Chassot,et al.  By-catch and discards of the european purse seinetuna fishery in the Indian Ocean : estimation and characteristics for the 2003-2007 period , 2008 .

[11]  Fao Danida Expert Consultation.  Guidelines for the routine collection of capture fishery data : prepared at the FAO/DANIDA Expert Consultation, Bangkok, Thailand, 18-30 May 1998 , 1999 .

[12]  J. Hallier,et al.  Review of tuna fisheries on floating objects in the Indian Ocean , 1992 .

[13]  D. L. Alverson,et al.  By-Catch: Problems and Solutions , 2000 .

[14]  D. Gaertner,et al.  Bycatch of billfishes by the European tuna purse-seine fishery in the Atlantic Ocean , 2002 .

[15]  R. J. Fryer,et al.  Fish discarded from Scottish demersal vessels: Estimators of total discards and annual estimates for targeted gadoids , 1999 .

[16]  Sara M. Maxwell,et al.  Shifting gears: assessing collateral impacts of fishing methods in US waters , 2003 .

[17]  E. F. Edwards,et al.  A mixture model for estimating discarded bycatch from data with many zero observations: tuna discards in the eastern tropical Pacific Ocean , 1996 .

[18]  F. J. Ariz-Tellería,et al.  Statistics of the main purse seine fleets fishing in the Indian Ocean (1981-2010) , 2011 .

[19]  S. J. Cripps,et al.  Defining and estimating global marine fisheries bycatch , 2009 .

[20]  Sean Pascoe,et al.  Bycatch management and the economics of discarding , 1997 .

[21]  A. Stull,et al.  Diel movements of scalloped hammerhead sharks, Sphyrna lewini Griffith and Smith, to and from a seamount in the Gulf of California , 1988 .

[22]  E. Romanov.  Bycatch in the tuna purse-seine fisheries of the western Indian Ocean , 2002 .

[23]  Marie-Joëlle Rochet,et al.  Factors for the variability of discards: assumptions and field evidence , 2005 .

[24]  J. Maguire.  The state of world highly migratory, straddling and other high seas fishery resources and associated species , 2006 .

[25]  Mihoko Minami,et al.  Modeling shark bycatch: The zero-inflated negative binomial regression model with smoothing , 2007, Fisheries Research.