Stress and survival of small pike-perch Sander lucioperca (L.) after trawling and chilling |
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Authors: | P Hyvärinen † V Leppäniemi ‡ K Johansson ‡ P Korhonen P Suuronen |
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Institution: | Finnish Game and Fisheries Research Institute, Kainuu Fisheries Research, Manamansalontie 90, FIN-88300 Paltamo, Finland; and Department of Biological and Environmental Sciences, Faculty of Biosciences, Viikinkaari 9, P. O. Box 56, FI-00014 University of Helsinki, Finland |
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Abstract: | The mortality and stress responses (plasma cortisol concentration) of undersized (total length, L T, <370 mm) pike-perch Sander lucioperca caught as by-catch in a trawl fishery were assessed. The effects of three different holding methods on pike-perch caught by trawl were compared: (1) fish that were transferred to ambient-temperature water (15·0–21·4° C) immediately after capture and not exposed to chilling water, (2) fish held in chilling water for 10 min and (3) fish exposed to chilling water for 2 h. The sample fish were held and monitored in individual plastic restrainers at ambient-water temperature for 48 h after each of the handling procedures. Total mortality was similar for fish held in chilling tanks for 10 min (27·2% total mortality) compared to fish that were only held in ambient-temperature water (28·2% mortality). Total mortality reached 91·3% when fish were held in chilled water for 2 h. Mortality and plasma cortisol concentrations correlated inversely with size (96–368 mm L T) and directly with lake-water temperature (15·0–21·4° C) after treatment. In addition, the effect of chilling was observed in elevated cortisol concentration and delayed start of recovery. The results show that quickly removing (<10 min) undersized pike-perch from chilled water could markedly improve the survival of released fish. Due to delayed recovery, however, fish should be allowed to recover (30–40 min) in a deck tank before release. |
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Keywords: | by-catch chilling mortality pike-perch Sander lucioperca trawling |
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