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Estimation du stock naturel d'ormeaux du golfe du Morbihan

The Gulf has very tiled sea beds, and the surface areas of habitats suitable for ormer populations are rather reduced (1.56km2). Three zones have ormer densities of interest from the point of view of profitability, Brannec, lrus and Creizig. But since their surface area is not great, the exploitable biomass, that corresponding to individuals of a size greater than 80mm (legal catch size), is average. These three zones would be exploitable but following a limited fishing effort. The sectors of Ile aux moines and Jument and Henn Tenn show average to low densities and are not therefore exploitable in a profitable way. Finally, Gavrinis and le Logeo have revealed low densities of ormers, this could be due to an intensive illegal exploitation. In fact, many overturned blocks were observed during sampling dives at the le Logeo sites. Moreover, it must be noted that there is an almost complete absence of the size class 75/85mm, which probably corresponds to the age class born in 1998. From this fact, a great deal of attention must be paid to it. Indeed, this deficit will in the next few years affect a part of the individuals of the exploitable population (size greater than 80 or 90mm). Finally, with the goal of place the Gulf of Morbihan in a wider context, some sampling points were done on Belle Ile and the wild coast of Quiberon. These observations revealed fine ormer densities generally greater than those of the Gulf populations. Thus, as far as the site studied as is, it seems difficult to imagine setting up sustainable exploitation there. On the other hand, according to observations made outside the Gulf, it seems that the area covered by the ormer populations is rather large. It would therefore be judicious to think about the question of setting up exploitation in a larger zone including, in particular, the Quiberon coasts, and Belle Ile. The fishing effort would in theory find itself more diffuse but the Gulf's protected enclosure would remain the most accessible.

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