Point, alpha and beta diversity of carnivorous fish along a depth gradient
In: Aquatic Living Resources = Ressources Vivantes Aquatiques. Elsevier: Montrouge. ISSN 0990-7440; e-ISSN 1765-2952, more
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| Keywords |
Characteristics > Diversity
Fisheries > Demersal fisheries
Fishing > Catching methods > Line fishing > Longlining
Probability distribution
Properties > Physical properties > Density
Species diversity
Canary I. [Marine Regions]; Canary I., Lanzarote [Marine Regions]
Marine/Coastal |
| Abstract |
The catch from bottom longline stations sampled from a series of research cruises around Lanzarote and Fuerteventura (Canary Islands,NE Atlantic) was analysed in terms of fish distribution, density and diversity. The distribution of the number of species and individualscaught per station appeared to fit well the Poisson and Exponential distribution function, respectively. In particular, the parameter of thePoisson’s distribution appeared to provide an index of the point (at station scale) diversity, and its confidence interval, allowing for statisticalcomparisons. The relationships between point diversity, the alpha diversity (in the depth strata) and the beta diversity (along the depthgradient) were investigated. Around the islands, the density and the point diversity of the predator fish declined with depth down to about800 m and then increased in the deeper stratum. The alpha diversity was the lowest in the deeper stratum but the taxonomic distinctnesswas similar to that of shallower strata. The beta diversity showed some faunal breaks along the depth gradient. The carnivorous fish faunacan be understood as comprised of three major assemblages: shelf, upper slope and mid-slope that are different both in terms of speciescomposition and point, alpha and beta diversities. The relevance of this simple method for ecological studies of fish assemblage in thecontext of non-trawlable grounds is discussed, in particular for the slope and other areas of established or developing deep-water fisheries. |
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