ISSN:
1573-5117
Keywords:
eels
;
salmonidae
;
competition
;
chalk streams
Source:
Springer Online Journal Archives 1860-2000
Topics:
Biology
Notes:
Abstract The age, growth, annual production and diet of the eel Anguilla anguilla were examined in a chalk stream in southern England. Growth in length fitted the von Bertalanffy model: L t = 708(1 − exp( − 0.064(t + 0.625))), where L t is the mean length (mm) at age t years. Annual length increments over the first 10 years averaged 31 mm, and annual production was 3.43 g m−2 y−1 (range 3.13–3.75). This fell to 2.09 (1.75–2.34) over two years as result of successive eel culls. Comparisons of eel diets with those of juvenile salmon Salmo salar and trout S. trutta showed that eels preyed more on benthic invertebrates, whereas the salmonids took more mid-water and surface prey. Piscivory was most marked in eels 〉400 mm, but few salmonids were eaten; most fish prey were the sculpin Cottus gobio. Attempts to reduce the eel population by successive eel culls were only partly successful because of the upstream immigration of elvers and downstream migration of silver eels into the study area. We conclude that, in this salmonid nursery stream, eels do not have a measurable effect on the salmonid population through predation or by utilizing the same food source.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1007/BF00006419
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