Age et croissance de Pagellus bellottii (Sparidae) des cotes Mauritaniennes
The red Pandora Pagellus bellottii is one of the most important demersal species in the fisheries of Mauritanian coasts. Several gears and fleet traditionally exploit it. The studies concerning this fish and particularly those of its age and growth are rare and haven't used the adequate method, which uses hard pieces like scale and vertebra. The objective of the present work is to contribute to the knowledge of the growth parameters of the red Pandora using the scales method not yet used in the studied area. To determine the age and to study the growth of Pagellus bellottii in Mauritanian coasts, we have used the scales of 544 individuals. We have taken, 8 scales under the fin pectoral and we have read the age using a binocular magnifying glass provided with an ocular micrometer. The ray of scale (R) and the rays of different slowing down of growth ring are raised along a centerline. For the determination of number of slowing down of growth rings annually formed and to determine their appearance period, we have analyzed the monthly variations of marginal lengthening (AM). To study the linear growth, we have established the relations binding size (FL) and total ray of the scale (R). Using the software "FSAS" based on the nonlinear adaptation of Maquardt, we have arranged the growth curve and determined the linear growth parameters of the Von Bertalanffy model. To check the obtained results, we have used the method of Ben Salem and Daget. Finally we have described mass growth, by the Von Bertalanffy equation, which expresses the mass evolution depending on the time. The study of age and growth of Pagellus bellottii of the Mauritanian coasts by the scalimetry method showed a minimal value of marginal lengthening in December for males and females. The graphic representation of marginal lengthening showed two principal decreases: the first in June-July coincides with the period of spawning; the second in December correspond to slowing down of growth ring. The estimate of the age using the slowing down of growth rings, allows distinguishing 8 age groups for males and 7 age groups for females The values of theorical length obtained by the Von Bertalanffy equation were nearly similar to those calculated by retrocalcul. We announce consequently that the model of Von Bertalanffy applies perfectly to the growth of Pagellus bellottii in Mauritanian coasts. The linear growth is practically the same for the two sexes while the mass growth is in favor of the males.Original Abstract: L'etude de l'age et de la croissance de Pagellus bellottii des cotes mauritaniennes par la lecture des ecailles (scalimetrie) montre que la valeur minimale de l'allongement marginal est enregistree au mois de Decembre pour les males et les femelles. L'examen des representations graphiques de l'allongement marginal montre deux principales chutes : une chute en juin-juillet qui coincide avec la periode de ponte, une deuxieme chute apparait en decembre et correspond a la formation de l'anneau de ralentissement de la croissance. Les parametres de la croissance lineaire L~ ! , K et t sub(0) relatifs a l'equation de Von Bertalanffy ont ete calcules a partir de deux methodes basees sur des iterations. Une courbe de Von Bertalanffy a ete ajustee aux donnees observees. Les valeurs des longueurs theoriques calculees a partir de l'equation de Von Bertalanffy sont tres proches ou egales a celles determinees par le retrocalcul, aussi bien chez les males que chez les femelles. Concernant la croissance massique, nous avons etabli d'une part les relations taille-masse et d'autre part, les relations masse-age. Ces dernieres ont ete deduites de l'equation du modele de Von Bertalanffy.
| Main Authors: | , , |
|---|---|
| Format: | Journal Contribution biblioteca |
| Language: | French |
| Published: |
INSTM
2004
|
| Subjects: | Pagellus bellottii Sparidae, Pagellus bellottii, Sparidae, Age, Age determination, Growth, Scale reading, |
| Online Access: | http://hdl.handle.net/1834/4245 |
| Tags: |
Add Tag
No Tags, Be the first to tag this record!
|