Zoeken
Zoeken kan via de modus 'eenvoudig zoeken' (één veld) of uitgebreid via 'geavanceerd zoeken' (meerdere velden). Zo kan je bv. zoeken op een combinatie van een auteursnaam (auteur), een jaartal (jaar) en een documenttype.
Boekenmand
Nuttige resultaten kan je aanvinken en toevoegen aan een mandje. De inhoud hiervan kan je exporteren of afdrukken (naar bv. PDF).
RSS
Op de hoogte blijven van nieuw toegevoegde publicaties binnen uw interessegebied? Dit kan door een RSS-feed (?) te maken van jouw zoekopdracht.
nieuwe zoekopdracht
North Sea Elasmobranchs: distribution, abundance and biodiversity
Daan, N.; Heessen, H.; ter Hofstede, R. (2005). North Sea Elasmobranchs: distribution, abundance and biodiversity. CM Documents - ICES, CM 2005(N:06). ICES: Copenhagen. 15 pp.
Deel van: ICES CM Documents - ICES. ICES: Copenhagen. ISSN 1015-4744, meer
|  |
| Trefwoorden |
Abundance
ANE, North Sea
Biodiversity
Distribution
Elasmobranchii [WoRMS]
Noordzee [Marine Regions]
Marien/Kust |
| Auteurs | | Top |
- Daan, N.
- Heessen, H.
- ter Hofstede, R.
|
|
|
| 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. |
IMIS is ontwikkeld en wordt gehost door het VLIZ.
