Native species of Sardinian brown trout (Salmo trutta) have declined drastically because of the introduction of non-native salmonids, overharvesting, and habitat degradation. One approach to conservation of declining species is to establish new populations through repopulation with genetically certified fish. In this study, samples of brown trout from seven rivers in Sardinia were analysed to look for the presence of pure individuals of the endemic Sardinian trout. Analyses of the mitochondrial DNA control region and the LDH-C1* gene revealed the presence of non-endemic and hybrid individuals in four of the seven rivers analysed. In addition, we reared a stock of native Sardinian trout at the experimental fish farm of Sadali and had them reproduce artificially. This experiment provided more knowledge about the incubation phase, hatching, reabsorption of the vitelline sac and the initial phases of growth, which can be used to develop more optimal management of this resource.
suMMArY: We investigated the spatial distribution, size structure, shell orientation and valve colonization by epibionts of the endangered Mediterranean bivalve Pinna nobilis in three continuous but different habitats in the Gulf of oristano (sardinia, western Mediterranean). the sampling stations chosen were: an estuarine area (e) of coastal salt-marshes characterized by unvegetated sea-bottoms; and two areas in a seagrass meadow characterized by an extensive Posidonia oceanica meadow (M w ) and patched mixed meadows of P. oceanica and Cymodocea nodosa (M e ). We found significant differences in mean densities among stations and the highest value was found in the estuarine area. shell orientation showed that there was uniform circular distribution of specimens in the M w station and a unimodal distribution in the M e and e stations, where specimens were set at 0°n and 10°nne, which is a pattern related to sea drift. shell epibiosis displayed differences between habitats. the highest valve colonization was in the estuary, with filamentous dark algae and Ostrea edulis reaching almost 90 percent of shell coverage. this study provides new information on habitat preferences and data for assessing local populations of P. nobilis that is useful for its conservation and improving the knowledge of its ecology.
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