USE AND EFFECT OF FREEZE BRANDING ON ROACH (RUTILUS RUTILUS L.)
We tested the effects of freeze branding on growth, survival and mark retention in roach Rutilus rutilus L. (82-268 mm in total length). Markings were applied at two positions on the skin: (1) the depressed area above the anal fin, (2) the muscles above the lateral line and between the caudal and dorsal fins. A control group received no mark. The experiment duration was 30 days, and 120 roach were selected and distributed into three lots. Retention rates were high and ranged between 94% for position 2 and 100% for position 1. Survival rate after 1 month was 87% for freeze branded roach at position 2, 90% for position 1 and 92% for unmarked fish. These differences were not statistically significant. A significant decrease of linear growth was observed for individuals marked at position 2 (3.2 mm.month-1), but the implication of the brand itself was unclear. We discuss the short- and long-term properties of freeze branding techniques on roach.
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Mots clés :
Marking technique, Retention, Survival and Growth rates, Cyprinids, Technique de marquage, taux de rétention, survie et croissance, Cyprinidae