In:
Ecology of Freshwater Fish, Wiley, Vol. 25, No. 2 ( 2016-04), p. 281-294
Abstract:
As a key parameter in the management of fish populations, individual growth rate ( GR ) variations were examined in the E uropean eel ( A nguilla anguilla ; 〉 150 mm) using extensive mark–recapture surveys in the lotic habitats of two small rivers of western F rance: the F rémur, supposed to be saturated, and at the same latitude, the O ir with densities fivefold lower than those of the F rémur. In both systems, generalised linear models were used to test whether spatiotemporal factors such as dominant habitat type or local density affect GR variability. In the presumed unsaturated system, the O ir, GR variability is mainly explained by a set of habitat suitability drivers (density, dominant habitat type). In the F rémur, GR s appear independent of differences in habitat density or productivity. Below saturation, an increase in density will decrease the GR through intraspecific competition. At saturation, intraspecific competition reaches such high levels that regardless of eel density and productivity, the resources available by individual are similar throughout the system. In these circumstances, the effect of density on growth was presumed undetectable. Despite these contrasted results, mean GR s observed in both catchments were closed (~20 mm·year −1 ). This is an unexpected result as GR is expected to be higher in unsaturated systems. This similarity could be explained by the difference between the two systems in terms of: (i) sex ratio (the Frémur is dominated by male, whereas the female is dominant in the O ir), (ii) habitat type distribution or (iii) possible interspecific competition (important salmonid populations in the O ir).
Type of Medium:
Online Resource
ISSN:
0906-6691
,
1600-0633
DOI:
10.1111/eff.2016.25.issue-2
Language:
English
Publisher:
Wiley
Publication Date:
2016
detail.hit.zdb_id:
2028166-3
SSG:
21,3
SSG:
12
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