viii
e. Le nombre moyen d'individus par estomac pour la proie « Nmt » ································ ··· 14
5. Paramètres de croissance ··················································································· 14
5.1. Croissance linéaire par analyse des structures de taille ··············································· 15
5.1.1. Estimation des paramètres de croissance L∞, K et t0 ··············································· 15
a. Méthode de Pauly (1985) ··················································································· 15
b. Méthode de Powell (1979) -Wetherall (1986) ································ ··························· 15
c. Méthode ELEFAN I (Pauly et Devid, 1981) ····························································· 15
5.2. Croissance relative (relation taille-poids) ································ ······························· 17
5.3. Croissance pondérale······················································································ 18
6.Exploitation ·································································································· 18
6.1. Estimation des paramètres de l’exploitation ································ ··························· 18
6.1.1. Mortalité totale (Z) : méthode de Pauly (1984) ····················································· 18
6.1.2. Mortalité naturelle (M) : méthode de Pauly (1980) ································ ················· 19
6.1.3. Mortalité par pêche F ·················································································· 19
6.2. Les modèles d’exploitation ································ ································ ············· 19
6.2.1. Modèle rétrospectif de Jones (1983) ································ ································ ·· 19
6.2.2. Le modèle prédictif de Thompson et Bell (1914) ··················································· 21
Chapitre 3 : Résultats et discussions
1.Quelques notions du stock ················································································· 22
1.1. La formule radiaire ······················································································· 22
1.2. Branchio-spines ································ ································ ··························· 22
1.3. La moyenne vertébrale ································ ································ ··················· 22
2.Les indices biologiques ································ ································ ···················· 23
2.1. Sex ratio ································ ································ ································ ··· 23
2.2. Coefficient de condition de Fulton Q································ ································ ··· 24
3. Etude du régime alimentaire································ ································ ··············· 25
3.1. Analyse qualitative du bol alimentaire de Coelorinchus caelorhincus ······························ 25
3.2.Analyse quantitative des habitudes alimentaires de Coelorinchus caelorhincus ··················· 27
3.2.1.Coefficient de vacuité ··················································································· 27
3.2.2.Fréquence et pourcentage en nombre ································································· 27
3.2.3.Nombre moyen (Nm et Nmt) ································ ································ ·········· 30
3.2.3.1.Variation du régime alimentaire en fonction de la taille chez les mâles ························ 30
3.2.3.2.Variation du régime alimentaire en fonction de la taille chez les femelles ····················· 32
3.2.3.3.Variation du régime alimentaire en fonction de la taille chez les indéterminés ..............···· 33
4. Etude de la croissance ······················································································ 37
4.1.Test de comparaison de la taille moyenne des mâles et des femelles ······························· 37
4.2. Détermination des paramètres de la croissance linéaire L∞ et K···································· 37
4.2.1. Cas des femelles ························································································ 38
4.2.2. Cas des mâles ··························································································· 41
4.2.3. Cas de la population globale (sexes confondus) ···················································· 43
e. Le nombre moyen d'individus par estomac pour la proie « Nmt » ································ ··· 14
5. Paramètres de croissance ··················································································· 14
5.1. Croissance linéaire par analyse des structures de taille ··············································· 15
5.1.1. Estimation des paramètres de croissance L∞, K et t0 ··············································· 15
a. Méthode de Pauly (1985) ··················································································· 15
b. Méthode de Powell (1979) -Wetherall (1986) ································ ··························· 15
c. Méthode ELEFAN I (Pauly et Devid, 1981) ····························································· 15
5.2. Croissance relative (relation taille-poids) ································ ······························· 17
5.3. Croissance pondérale······················································································ 18
6.Exploitation ·································································································· 18
6.1. Estimation des paramètres de l’exploitation ································ ··························· 18
6.1.1. Mortalité totale (Z) : méthode de Pauly (1984) ····················································· 18
6.1.2. Mortalité naturelle (M) : méthode de Pauly (1980) ································ ················· 19
6.1.3. Mortalité par pêche F ·················································································· 19
6.2. Les modèles d’exploitation ································ ································ ············· 19
6.2.1. Modèle rétrospectif de Jones (1983) ································ ································ ·· 19
6.2.2. Le modèle prédictif de Thompson et Bell (1914) ··················································· 21
Chapitre 3 : Résultats et discussions
1.Quelques notions du stock ················································································· 22
1.1. La formule radiaire ······················································································· 22
1.2. Branchio-spines ································ ································ ··························· 22
1.3. La moyenne vertébrale ································ ································ ··················· 22
2.Les indices biologiques ································ ································ ···················· 23
2.1. Sex ratio ································ ································ ································ ··· 23
2.2. Coefficient de condition de Fulton Q································ ································ ··· 24
3. Etude du régime alimentaire································ ································ ··············· 25
3.1. Analyse qualitative du bol alimentaire de Coelorinchus caelorhincus ······························ 25
3.2.Analyse quantitative des habitudes alimentaires de Coelorinchus caelorhincus ··················· 27
3.2.1.Coefficient de vacuité ··················································································· 27
3.2.2.Fréquence et pourcentage en nombre ································································· 27
3.2.3.Nombre moyen (Nm et Nmt) ································ ································ ·········· 30
3.2.3.1.Variation du régime alimentaire en fonction de la taille chez les mâles ························ 30
3.2.3.2.Variation du régime alimentaire en fonction de la taille chez les femelles ····················· 32
3.2.3.3.Variation du régime alimentaire en fonction de la taille chez les indéterminés ..............···· 33
4. Etude de la croissance ······················································································ 37
4.1.Test de comparaison de la taille moyenne des mâles et des femelles ······························· 37
4.2. Détermination des paramètres de la croissance linéaire L∞ et K···································· 37
4.2.1. Cas des femelles ························································································ 38
4.2.2. Cas des mâles ··························································································· 41
4.2.3. Cas de la population globale (sexes confondus) ···················································· 43