Recapture rate, growth and sex of stocked cultured eels Anguilla anguilla (L.)

Abstract

A total of 84,791 Alcian blue marked eels, size range 15-33 cm, were released in a lake, a fjord and an open coastal area. Recaptures were made by fishermen up to 4 years following release. Recaptures were most successful at the freshwater lake where 12.6 % were recaptured, 2.7 % in the fjord and 0.2 % at the open coast. Length increment was estimated to be between 2.5 and 6.5 cm annually. The sex ratio (female/male) of yellow eels increased in subsequent years of recaptures, possibly as a result of environmental sex determination following release. The use of Alcian blue for a long-term marking experiment, based on samplings by fishermen, are concluded to be questionable.