Low fat contents in female silver eels: Indications of insufficient energetic stores for migration and gonadal development

Abstract

The main energetic stores at the silver eel stage were studied by analysing muscle fat concentrations and hepatosomatic indices in female silver eels from various habitats in Sweden. Muscle fat concentrations varied both within and between localities and lean eels with muscle fat concentrations <20% occurred at all study sites. Furthermore, no correlation could be found between muscle fat content and internal or external maturation indices, neither was the relative liver size related to the maturation process, as the correlation between the hepatosomatic and gonadosomatic indices was very weak. Consequently, it was concluded that silvering and the spawning migration may begin also at low muscle fat concentrations. However, most of the energy reserve is stored as muscle fat in eel, and it is highly unlikely that female silver eels with such low fat contents, as were observed occasionally in this study, will ever recruit to the next generation. Therefore, it is suggested that the maturation process in eel is more flexible than previously recognized, and that this process might be temporarily arrested and feeding resumed during the first part of the migratory phase. (C) 1997 The Fisheries Society of the British Isles.

Keywords

Anguilla anguilla; maturation; muscle fat content; hepatosomatic index; energetic status; spawning migration

Published in

Journal of Fish Biology
1997, volume: 50, number: 3, pages: 475-486
Publisher: ACADEMIC PRESS LTD

UKÄ Subject classification

Developmental Biology
Evolutionary Biology
Ecology


Publication identifier

DOI: https://doi.org/10.1111/j.1095-8649.1997.tb01943.x

Permanent link to this page (URI)

https://res.slu.se/id/publ/42022