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Lowering treatment temperature reduces salmon mortality: a new way to treat with hydrogen peroxide in aquaculture
Author(s) -
Overton Kathy,
Samsing Francisca,
Oppedal Frode,
Stien Lars H,
Dempster Tim
Publication year - 2018
Publication title -
pest management science
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.296
H-Index - 125
eISSN - 1526-4998
pISSN - 1526-498X
DOI - 10.1002/ps.4751
Subject(s) - hydrogen peroxide , bathing , aquaculture , mortality rate , zoology , fish <actinopterygii> , biology , fishery , fish mortality , toxicology , medicine , surgery , biochemistry , pathology
BACKGROUND Hydrogen peroxide (H 2 O 2 ) baths are widely used to reduce numbers of salmon lice on farmed Atlantic salmon. Fish mortalities often occur after baths, with warmer temperatures increasing lethality. We tested whether mortality could be reduced and lice removal efficacy maintained by lowering bath temperatures relative to ambient temperatures. Post‐smolt salmon infected with lice were held at 10, 13 or 16 °C, and treated with 1.5 g/L H 2 O 2 for 20 min at equal or lower bath temperatures of 7, 10 or 13 °C. RESULTS Salmon mortality decreased as ambient and bath temperatures decreased. No mortality occurred when fish at 13 °C were treated at 7 °C. For ambient temperatures of 16 °C, the number of lice remaining was reduced by four‐fold when treated at 7 °C compared with 13 °C. All treatments in which mortality was zero had similar efficacies regardless of bath temperature. CONCLUSION We took salmon from warmer to colder temperatures to determine the optimum bathing temperature to prevent mortality. A temperature of 7 °C was optimal when treating with 1.5 g/L of H 2 O 2 , as mortality was zero and pre‐adult lice removal was unchanged. By manipulating temperature, we developed a new method of H 2 O 2 bathing that reduces mortality. When ambient temperatures are >10 °C, we recommend that the industry decrease H 2 O 2 bath temperatures. © 2017 Society of Chemical Industry