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Consistent melanophore spot patterns allow long‐term individual recognition of Atlantic salmon Salmo salar
Author(s) -
Stien L. H.,
Nilsson J.,
Bui S.,
Fosseidengen J. E.,
Kristiansen T. S.,
Øverli Ø.,
Folkedal O.
Publication year - 2017
Publication title -
journal of fish biology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.672
H-Index - 115
eISSN - 1095-8649
pISSN - 0022-1112
DOI - 10.1111/jfb.13491
Subject(s) - salmo , biology , operculum (bryozoa) , spots , melanophore , fishery , fish <actinopterygii> , zoology , chromatophore , botany , genus
The present study shows that permanent melanophore spot patterns in Atlantic salmon Salmo salar make it possible to use images of the operculum to keep track of individual fish over extended periods of their life history. Post‐smolt S. salar ( n = 246) were initially photographed at an average mass of 98 g and again 10 months later after rearing in a sea cage, at an average mass of 3088 g. Spots that were present initially remained and were the most overt (largest) 10 months later, while new and less overt spots had developed. Visual recognition of spot size and position showed that fish with at least four initial spots were relatively easy to identify, while identifying fish with less than four spots could be challenging. An automatic image analysis method was developed and shows potential for fast match processing of large numbers of fish. The current findings promote visual recognition of opercular spots as a welfare‐friendly alternative to tagging in experiments involving salmonid fishes.