CONTRIBUTION TO THE BIOLOGICAL STUDY OF THE BLUE SHARK “PRIONACE GLAUCA” IN MOROCCAN WATERS.

Abstract

The pelagic blue shark “Prionace glauca”, forming the top of the trophic chain gill is essential to the balance of the marine ecosystem. Overfishing, pollution and climate change in recent decades were certainly the causes of the decline in the number of pelagic sharks including blue shark. The latter is classified as Near Threatened "NT" in the red list of the IUCN (International Union for Conservation of Nature). In this context and in order to achieve biological and ecological studies used as elements required for better preservation of this shark, scientific monitoring was initiated in Morocco. Since February 2015 biological sampling sessions were conducted in Casablanca wholesale market receiving landings of blue shark of all Moroccan ports. The size distribution of structures showed a modal class of 130 cm in males as well as females. The size at first maturity of males is 188.54 cm. Analysis of sex ratio showed that females slightly dominate males generally with a rate of 52%. The female dominance is much clearer in the spring-summer season while preponderance of males is noted during autumn-winter seasons. On growth, the coefficient b was above 3 showing that the growth of the blue shark weight is more important than size.

Keywords

• Prionace glauca
• demographic structure
• size
• first maturity
• growth
• Morocco