European eel (Anguilla anguilla): prediction of spawner escapement from continental population parameters
This paper describes the assessment of silver European eel (Anguilla anguilla) escapement based on a “sedentary” population fraction analysis in a 60-km2 watershed of northern Brittany (France). Downstream migration fluxes were monitored using eel traps and related to environmental factors. Intensiv...
| Published in: | Canadian Journal of Fisheries and Aquatic Sciences |
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| Main Authors: | , , , |
| Other Authors: | , , |
| Format: | Article in Journal/Newspaper |
| Language: | English |
| Published: |
NRC Research Press
2000
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| Subjects: | |
| Online Access: | http://oatao.univ-toulouse.fr/6151/ http://oatao.univ-toulouse.fr/6151/1/feunteun_6151.pdf https://doi.org/10.1139/f00-096 |
| Summary: | This paper describes the assessment of silver European eel (Anguilla anguilla) escapement based on a “sedentary” population fraction analysis in a 60-km2 watershed of northern Brittany (France). Downstream migration fluxes were monitored using eel traps and related to environmental factors. Intensive electrofishing and fyke-net fishing were conducted to assess eel biomass, densities, and population structure. A total of 564 eels, including 81 silver eels, were PIT tagged. In 1996, 616 eels were caught in the catchment including 68 silver eels (11%). During the following downstream migration period, 12 of the PIT-tagged silver eels, among a total of 678, were recaptured in the downstream traps. Seven were recaptured in the catchment in 1997. It was shown that (i) only about 20% of the silver eels present in the catchment emigrated during the following year, (ii) 12% stayed in the catchment including two (3.4%) that recovered yellow eel characteristics, and (iii) the other eels either died or settled in the catchment but were not recaptured. It was also estimated that 2% (650 eels) of the population (34 000 eels) among 3000 silver eels considered “emigration candidates” emigrated each year. |
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