Opvolging van het visbestand van de Zeeschelde: resultaten voor 2012
Breine, J.; Van Thuyne, G. (2013). Opvolging van het visbestand van de Zeeschelde: resultaten voor 2012. Rapporten van het Instituut voor Natuur- en Bosonderzoek, INBO.R.2013.13. Instituut voor Natuur- en Bosonderzoek (INBO): Brussel. 66 pp.
Part of: Rapporten van het Instituut voor Natuur- en Bosonderzoek. Instituut voor Natuur- en Bosonderzoek: Brussel. ISSN 1782-9054
In researchers of the Research Institute for Nature and Forest (INBO) performed three fish surveys in theZeeschelde estuary. Fish assemblages were surveyed in six locations nearby the banks during spring, summer and autumn using paired fyke nets.In total 33 fish species were caught. Largest numbers of fish were caught mainly in spring. In summer we caught the highest number of individuals. Fish assemblages in each location are different.Flounder is the most abundantly caught species in the Zeeschelde. In spring smelt and three-spined stickleback are caught in large numbers. In summer flounder and common goby are the most abundant species. In autumn we mainly caught flounder and smelt.Statistical analyses indicated a significant temporal and spatial difference in fish assemblages. Even within one location seasonal and yearly changes occur.The presence of large numbers of twaite shad and smelt was remarkable.The fish-based index indicated that the mesohaline zone is no longer in the “moderate” status but in a “poor” status. The decrease in number of individuals caught is an indication of ecological degradation. The oligohaline zone remained in a “poor” status. The freshwater zone now has reached the “GEP” status.The length frequency distribution indicated that the following species use the estuary as a nursery: flounder, seabass, herring and sole. Other species spawn in the estuary: roach, bream, smelt and twaite shad.Data obtained from the volunteers added nine more species to those caught by the INBO.
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