EVALUATION OF THREE EXTERNAL MARKING METHODS FOR DIFFERENTIATING FARMED AND WILD ATLANTIC SALMON

摘要

In the recent past, fish escapes from sea cages become one of the major environmental issues (Jensen et al. 2010). To monitor and identify farmed fish escapees an identification system that distinguishes between farmed and wild fish is necessary. Various marking methods, such as fin clipping, genetic marking and external and internal tags have been used to identify individual fish over the decades. Selection of an appropriate marking method is largely dependent on the aim of the study, cost effectiveness, retainability of the mark, effects on fish growth, survival and welfare and logistics such as detectability of the mark and legality of the method. To evaluate the efficiency of external marks we have selected the three external marks; Visible Implant Elastomer (VIE), Adipose fin clipping (AF) and freeze branding (FB) in the current study. The major objectives of this study were to evaluate the effects of; 1. the individual (VIE, AF and FB) marking methods on growth and survival of the fish and durability and readability of the mark, 2. the location of marking (FB and VIE) on growth and survival of the fish and mark retention and readability; and 3. partial and complete removal of AF on the growth and survival of the fish and regeneration of thefin. We report here only the results from 1 & 3.