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Evaluation of Growth Interruption as a Means of Manipulating Scale Patterns for Mass‐Marking Hatchery Trout
Author(s) -
Bigelow Patricia E.,
White Robert G.
Publication year - 1996
Publication title -
north american journal of fisheries management
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.587
H-Index - 72
eISSN - 1548-8675
pISSN - 0275-5947
DOI - 10.1577/1548-8675(1996)016<0142:eogiaa>2.3.co;2
Subject(s) - hatchery , trout , stocking , oncorhynchus , fishery , fish <actinopterygii> , biology , rainbow trout , scale (ratio) , environmental science , geography , cartography
Despite the importance of marking fish, there is substantial need for improvement in types of marks used, methods of administering them, and means of mark detection. Our study was conducted to assess the possibility of mass‐marking hatchery‐reared cutthroat trout Oncorhynchus clarki by inducing recognizable patterns on scales by manipulating feeding regime and water temperature. Changes in feeding regime and, somewhat less precisely, water temperature effectively altered circulus spacing on trout scales. Models based on scale pattern analysis of fish in experimental groups receiving different amounts of food had mean classification accuracies of 95.6, 80.9, 91.2, and 96.4% correct; in groups exposed to fluctuating water temperature, classifications were 95.2, 79.8, and 78.5% correct. Marks were used to accurately predict fish group origin, making this a simple, inexpensive, efficient, and harmless method of mass‐marking hatchery trout. This technique will be useful in evaluating the suitability of different strains of hatchery trout in management situations, stocking strategies, size of fish at release, and influence of diet on survival. To improve the usefulness of this technique, fish size at marking, duration of marking period, length of the posttreatment period needed for the mark to be reflected in scale patterns. and scale sample selection need additional examination.