Staff Publications

Staff Publications

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    'Staff publications' is the digital repository of Wageningen University & Research

    'Staff publications' contains references to publications authored by Wageningen University staff from 1976 onward.

    Publications authored by the staff of the Research Institutes are available from 1995 onwards.

    Full text documents are added when available. The database is updated daily and currently holds about 240,000 items, of which 72,000 in open access.

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Record number 340693
Title North Sea Elasmobranchs: distribution, abundance and biodiversity
Author(s) Daan, N.; Heessen, H.J.L.; Hofstede, R. ter
Source Copenhagen : ICES (ICES CM 2005/N:06) - 15 p.
Department(s) RIVO Biologie en Ecologie
Publication type Research report
Publication year 2005
Abstract Based on data from various international and national surveys, an overview is given of the fine-scale distribution (resolution of 20¿longitude * 10¿ latitude; ¿ 10*10 nm) and trends in abundance of elasmobranch species reported from the North Sea. Presence-absence maps are produced based on 4 surveys, which help to delineate distribution limits of the less common species, while maps in terms of catch rates (International Bottom Trawl Survey data only) are given for the seven most common shark and ray species. While the results largely confirm published information, the higher resolution helps to delineate actual concentrations, which should prove useful when trying to relate abundance to habitat requirements. Trends in abundance do not reveal a consistent pattern across species. Some have markedly increased over the last 30 years, some have markedly decreased and some have remained remarkably stable. In a separate analysis, the information on number of species is integrated in a spatial biodiversity index for the elasmobranch community, by applying a novel method of correcting for differences in sampling effort. Although there are conceptual scientific problems in applying such biodiversity indices because of arbitrary choices of the level of effort for which the index is calculated, a highly consistent pattern emerges: a strong east-west gradient, with the species-richest elasmobranch community being largely restricted to the area off the British coast from the Channel to the Shetlands and virtually no elasmobranch species along the continental coast. This has clear implications for management, because any measure aimed at their conservation should take these spatial effects into account
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