Cet ouvrage fait partie de la bibliothèque YouScribe
Obtenez un accès à la bibliothèque pour le lire en ligne
En savoir plus

… diverses populations: adaptations comportementales …

De
4 pages

… diverses populations: adaptations comportementales …

Publié par :
Ajouté le : 21 juillet 2011
Lecture(s) : 0
Signaler un abus
1/4
THESE (PhD)
Présentée devant L’Ecole Nationale Supérieure Agronomique de Rennes
pour obtenir le titre de docteur de l’Ensar
Spécialité: HALIEUTIQUE
par
Patrice Brehmer
«
Analyse comparée des caractéristiques dynamiques et spatiales des bancs de
Sardinella
aurita
(Valenciennes, 1847) de diverses populations: adaptations comportementales face à
l’environnent et à l’exploitation ; effet sur la capturabilité
»
Directeur: François Gerlotto (IRD, Valparaiso)
Rapporteur: Thang DoChi (CNRS-Université de Montpellier II, Montpellier)
Rapporteur: Jacques Sacchi (Ifremer, Sète)
Examinateur: Andrew Bakun (Université de Miami, Floride)
Examinateur: Didier Gascuel (Ensar, Rennes)
Examinateur: Denis Reale (Univsersité du Québec, Montréal)
Examinateur: Jean Guillard (INRA, Thonon-les-bains)
Abstract
The behaviour of fish school, functional unit on which the fishing pressure focus in general, is
the major source of bias of the biomass index obtained by the methods of stock assessment
(echo-integration, scientific fishing etc..). This work, want to measure the possible relation
between the fishing effort and the fish school avoidance reaction. In this goal, we have made a
comparative approach from three genetically independent stock of
Sardinella aurita
, with a
similar environment but a different historical fishing exploitation. The avoidance behaviour
generated by the boat perception (acoustic, visual and tactile), can be measured by the
in situ
school kinematic. We have developed
Infobancs
software for the exploitation of
omnidirectional sonar data and an observation methodology, considering the boat in cruise or
in drift. The environment, (biotic, abiotic) and the intrinsic characteristics of the population
have a direct impact on this behaviour, which is expressed by morphological deformation and
three distinct wave of avoidance. We present the hypothesis of a innate of acquired of the
avoidance reaction. Our results show for a same fishing effort, catches more important in
Venezuela than in Senegal and Ivory Coast. More over the spatial and kinematics
in situ
observations of school show an avoidance behaviour different in Venezuela, in front of the
two Africans stocks. This indicate the existence of a link between fishing effort and the
avoidance, and so the adaptative response to the fishing pressure. This behavioural adaptation
comes from a Darwin selection process and/or a learning of the
Sardinella aurita
populations
to the fishing exploitation. In order to measure the bias engendered by the avoidance on the
stock management, we discuss of the conception of virtual fish school and the possibilities of
a continuous three-dimensional recording of the avoidance reaction.
Un pour Un
Permettre à tous d'accéder à la lecture
Pour chaque accès à la bibliothèque, YouScribe donne un accès à une personne dans le besoin