Objectif Anchovy is a species that constitutes an important resource for the fleets of the south-eastern Bay of Biscay (Spain and France). The fishery has historically been mainly Spanish, with a small share for the French. Catches have changed greatly over the last forty years, with a maximum of about 80.000 tons per year to a minimum of some 4.000 in the early eighties. They have since fluctuated considerably between the latter figure and 24.000 tons, but the trend is clearly declining. Some measures have been proposed in order to manage the stock, such as precautionary total allowable catches (TAC) and minimum landing size, but they have not apparently taken into account the nature of fluctuations, which is most likely fishery independent. An assessment of the stock by direct methods, along with a study of the environmental conditions, seems essential for the regulation of the fishery. Bearing this in mind, the project has been designed to compare 2 direct methods which have proved efficient in other fisheries: acoustic surveys and the daily egg production method (DEPM). The latter estimates the spawning stock biomass, and the former gives very good estimates of the total stock biomass. By comparing the results of both methods, it is expected to achieve an accurate knowledge of the stock abundance. The shortcomings of the acoustic and daily egg production (DEPM) methods of assessing fish stocks as applied to the Bay of Biscay anchovy have been identified and corrected. Both methods indicate similar trends in describing the fluctuations of the anchovy population in the period 1989 to 1992. The methodology of the acoustic surveys was found to be appropriate for the area and season of study. Statistical analyses and tests proved the sampling strategy for the DEPM are also appropriate. With respect to the consistency of the production estimates the jack knife technique was applied to the egg data collected during the 1992 survey. It showed that the daily production is well determined by the model.An important series of observations on the environmental and meteorological conditions has been carried out during the surveys. Sexual maturity seems to require a certain temperature of sea water. The distribution of eggs as well as the vertical and horizontal distribution of the adult anchovy may be influenced by the different moves of the water masses. No correlation between temperature, salinity and spawning intensity is evident.The genotypic and phenotypic characters of the Bay of Biscay anchovy have been thoroughly studied. 2 different groups seem to form the population although the results do not support the pure or discrete stock concept.The study of the variability of sexual maturity in space and time was done by the observation on the gonosomatic index. The variation of maturity can be modelled by the combined influence of several variables (ie sea water surface, salinity and fish weight). The observations have made evident the existence of maturity waves, and a different timing of the maturation of large and small anchovy.The relationship of meteorological and environmental conditions with respect to recruitment has been analyzed. Upwelling is the only factor that seems to be positively correlated with recruitment.The field work will be accomplished by a series of cruises named DAAG (Distribution et Abondance de l'Anchois dans le golfe de Gascogne) and BIOMAN (biomasa de la anchoa). Simultaneously, several aspects of the reproductive biology of the species will be taken into consideration. Success in reproduction is most important for the stock of anchovy, whose very short life span makes the stock most sensitive to weak year classes or cohorts. Environmental factors are also to be taken into consideration. Their study is hoped to give some explanations on the vertical and horizontal distribution of the population, as well as about its availability to fishing gears. Data on this item will be collected and analyzed over the whole period covered by the project, along with a historical series of hydrological parameters and data on catch by size. Champ scientifique agricultural sciencesagriculture, forestry, and fisheriesfisheriesnatural sciencesphysical sciencesacousticsagricultural sciencesagricultural biotechnologybiomassnatural sciencesbiological sciencesreproductive biology Programme(s) FP2-FAR - Community research and coordination programmes (EEC) in the fisheries sector, 1988-1992 Thème(s) Data not available Appel à propositions Data not available Régime de financement Data not available Coordinateur Instituto Espanol de Oceanografia Contribution de l’UE Aucune donnée Adresse Apartado de Correos 240 Promontorio de San Martin 39080 Santander Espagne Voir sur la carte Coût total Aucune donnée Participants (2) Trier par ordre alphabétique Trier par contribution de l’UE Tout développer Tout réduire AZTI-SIO Espagne Contribution de l’UE Aucune donnée Adresse Donostia-San Sebastian Voir sur la carte Coût total Aucune donnée Institut Français de Recherche pour l'Exploitation de la Mer (IFREMER) France Contribution de l’UE Aucune donnée Adresse Station de Nantes Rue de l'Ile d'Yeu 44037 Nantes Voir sur la carte Coût total Aucune donnée
