WWW.WAS.ORG • WORLD AQUACULTURE • MARCH 2023 15 In each issue of World Aquaculture, we highlight exciting papers from the Journal of the World Aquaculture Society. In this issue we highlight the paper “Water quality, waste production, and off-flavor characterization in a depuration system stocked with market-size Atlantic salmon Salmo salar” by J. Davidson, N. Redman, C. Crouse and B. Vinci. The article appears in the Journal of the World Aquaculture Society, volume 54, issue 1, pages 96-112. It is available at: https://doi.org/10.1111/jwas.12920 or under the Publications tab at the WAS website (www.was.org). Many challenges come with land-based finfish aquaculture. This study looks at water quality changes during remediation of offflavor that can accumulate in Atlantic salmon Salmo salar, reared in recirculating aquaculture systems (RAS). To eliminate off-flavor from salmon flesh, depuration may be necessary. Therefore, the authors emphasize the need to understand water quality and waste production in the context of depuration, discharge requirements or repurposing water back into the RAS. This study evaluated these parameters for 311 salmon ranging from 5-6 kg. These fish were reared to this size in a freshwater RAS and then moved to a Recent Research Highlight from the Journal of the World Aquaculture Society depuration tank. Feed was withheld one day prior to transfer and fish remained off-feed for the seven days of the study. Within hours after stocking, levels of total suspended solids (TSS), total phosphorus (TP), and total ammonia nitrogen (TAN) increased sharply and then declined. By the end of the trial TSS and TP were low but TAN plateaued, suggesting catabolism of somatic tissue. Geosmin and 2-methylisoboreol levels were also low throughout the study. This work represents the first comprehensive analysis of water quality and waste production during depuration of RAS-produced Atlantic salmon. Recommendations from this study include extending the duration of preliminary feed withholding prior to transfer into depuration systems and reintroducing depuration system water strategically within RAS to rapidly remove residual solids and ammonia prior to water reuse. These data provide important water quality measures to consider in design or configuration of existing or new RAS facilities. The full issue 54(1) is available at onlinelibrary.wiley.com/ toc/17497345/2022/54/1. — Kenneth Cain, Executive Editor, JWAS
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