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Mass marking of stocked E uropean glass eels ( A nguilla anguilla ) with alizarin red S
Author(s) -
Caraguel JeanMarie,
Charrier Fabien,
Mazel Virgile,
Feunteun Eric
Publication year - 2015
Publication title -
ecology of freshwater fish
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.667
H-Index - 55
eISSN - 1600-0633
pISSN - 0906-6691
DOI - 10.1111/eff.12158
Subject(s) - stocking , otolith , fishery , zoology , fish <actinopterygii> , marsh , electrofishing , biology , ecology , wetland
This study describes a mass marking method suitable for E uropean glass eel A nguilla anguilla , avoiding osmotic shock and reducing fish stress. During a single day, 360,000 glass eels intended for a stocking operation were bathed into an alizarin red S ( ARS ) solution, at a density of 346 ind.·l −1 before being released into a freshwater marsh along with unmarked glass eels. After 15 days, examination of marked and unmarked eels kept in enclosures in the marsh showed 100% of otoliths had been successfully marked and that no excess deaths related to marking process had occurred. Seven months after stocking, results from biometric measurements and otolith analysis, carried out on a sample of 53 elvers caught by electrofishing and belonging to the size class of the 0 + cohort, suggest that: (i) the proportions of marked and unmarked remained unchanged, hence suggesting that the marking process had not caused excess mortality, (ii) there was no difference in length, body mass or condition factor between marked and unmarked individuals, demonstrating that marking had caused no harmful effect after 7 months, and (iii) ARS marks in otoliths remained clearly visible. The benefits of this ARS mass marking technique are discussed through a stocking operation.