Variations in the population dynamics of the European eel Anguilla anguilla (L.) along the course of a Cantabrian river
Abstract– The size, density and production rate of eel were determined at 16 contrasting sites of 4 streams along the course of a Cantabrian river over the years 1990–1993. In addition, the diel cycles of feeding activity were determined monthly in another tributary over the year 1991–1992. Eels in...
Published in: | Ecology of Freshwater Fish |
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crwiley:10.1111/j.1600-0633.1995.tb00023.x 2024-09-09T19:00:44+00:00 Variations in the population dynamics of the European eel Anguilla anguilla (L.) along the course of a Cantabrian river Lobón‐Cerviá, J. Utrilla, C. G. Rincón, P. A. 1995 http://dx.doi.org/10.1111/j.1600-0633.1995.tb00023.x https://api.wiley.com/onlinelibrary/tdm/v1/articles/10.1111%2Fj.1600-0633.1995.tb00023.x https://onlinelibrary.wiley.com/doi/pdf/10.1111/j.1600-0633.1995.tb00023.x en eng Wiley http://onlinelibrary.wiley.com/termsAndConditions#vor Ecology of Freshwater Fish volume 4, issue 1, page 17-27 ISSN 0906-6691 1600-0633 journal-article 1995 crwiley https://doi.org/10.1111/j.1600-0633.1995.tb00023.x 2024-08-01T04:23:33Z Abstract– The size, density and production rate of eel were determined at 16 contrasting sites of 4 streams along the course of a Cantabrian river over the years 1990–1993. In addition, the diel cycles of feeding activity were determined monthly in another tributary over the year 1991–1992. Eels in the Esva were small, short‐lived and mostly males (>99%). The seasonal patterns of eel density, feeding activity and condition were tightly fitted with each other, size‐independent and regulated mainly by water temperature. Mean eel size increased with distance from the river mouth, but at each site, it remained similar between seasons and years. In contrast, density decreased upstream and showed marked seasonal and annual fluctuations. For all the sites, the number of eels increased in spring and summer and peaked by late autumn, coincident with higher water temperature and lower discharge. Mortality and migration rates were correlated with eel numbers for each stream, suggesting a densitydependent regulation. Production rates were correlated with distance from the river mouth, which explained only 10.2% of the variation, but they were also correlated with the initial and mean numbers, suggesting that site‐specific factors acting upon density also influence production. Average production for the first year was 158.6 kg – ha –1 . year –1 (range 56.5–378.0) but decreased to 104.2 and 89.7 in the next 2 years. The reduction in the numbers of eels rather than the later reduction in mean size was responsible for this decrease. Monthly water temperature, distance from the river mouth and the initial number and size of eels for each site explain most of the variation observed in the population parameters along the course of the Esva River. Article in Journal/Newspaper Anguilla anguilla Wiley Online Library Ecology of Freshwater Fish 4 1 17 27 |
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Abstract– The size, density and production rate of eel were determined at 16 contrasting sites of 4 streams along the course of a Cantabrian river over the years 1990–1993. In addition, the diel cycles of feeding activity were determined monthly in another tributary over the year 1991–1992. Eels in the Esva were small, short‐lived and mostly males (>99%). The seasonal patterns of eel density, feeding activity and condition were tightly fitted with each other, size‐independent and regulated mainly by water temperature. Mean eel size increased with distance from the river mouth, but at each site, it remained similar between seasons and years. In contrast, density decreased upstream and showed marked seasonal and annual fluctuations. For all the sites, the number of eels increased in spring and summer and peaked by late autumn, coincident with higher water temperature and lower discharge. Mortality and migration rates were correlated with eel numbers for each stream, suggesting a densitydependent regulation. Production rates were correlated with distance from the river mouth, which explained only 10.2% of the variation, but they were also correlated with the initial and mean numbers, suggesting that site‐specific factors acting upon density also influence production. Average production for the first year was 158.6 kg – ha –1 . year –1 (range 56.5–378.0) but decreased to 104.2 and 89.7 in the next 2 years. The reduction in the numbers of eels rather than the later reduction in mean size was responsible for this decrease. Monthly water temperature, distance from the river mouth and the initial number and size of eels for each site explain most of the variation observed in the population parameters along the course of the Esva River. |
format |
Article in Journal/Newspaper |
author |
Lobón‐Cerviá, J. Utrilla, C. G. Rincón, P. A. |
spellingShingle |
Lobón‐Cerviá, J. Utrilla, C. G. Rincón, P. A. Variations in the population dynamics of the European eel Anguilla anguilla (L.) along the course of a Cantabrian river |
author_facet |
Lobón‐Cerviá, J. Utrilla, C. G. Rincón, P. A. |
author_sort |
Lobón‐Cerviá, J. |
title |
Variations in the population dynamics of the European eel Anguilla anguilla (L.) along the course of a Cantabrian river |
title_short |
Variations in the population dynamics of the European eel Anguilla anguilla (L.) along the course of a Cantabrian river |
title_full |
Variations in the population dynamics of the European eel Anguilla anguilla (L.) along the course of a Cantabrian river |
title_fullStr |
Variations in the population dynamics of the European eel Anguilla anguilla (L.) along the course of a Cantabrian river |
title_full_unstemmed |
Variations in the population dynamics of the European eel Anguilla anguilla (L.) along the course of a Cantabrian river |
title_sort |
variations in the population dynamics of the european eel anguilla anguilla (l.) along the course of a cantabrian river |
publisher |
Wiley |
publishDate |
1995 |
url |
http://dx.doi.org/10.1111/j.1600-0633.1995.tb00023.x https://api.wiley.com/onlinelibrary/tdm/v1/articles/10.1111%2Fj.1600-0633.1995.tb00023.x https://onlinelibrary.wiley.com/doi/pdf/10.1111/j.1600-0633.1995.tb00023.x |
genre |
Anguilla anguilla |
genre_facet |
Anguilla anguilla |
op_source |
Ecology of Freshwater Fish volume 4, issue 1, page 17-27 ISSN 0906-6691 1600-0633 |
op_rights |
http://onlinelibrary.wiley.com/termsAndConditions#vor |
op_doi |
https://doi.org/10.1111/j.1600-0633.1995.tb00023.x |
container_title |
Ecology of Freshwater Fish |
container_volume |
4 |
container_issue |
1 |
container_start_page |
17 |
op_container_end_page |
27 |
_version_ |
1809941705493839872 |