Growth, feed conversion, sexual maturation, and cataract formation in coho (Oncorhynchus kisutch) and Atlantic (Salmo salar) salmon post-smolts reared at different salinities in recirculating aquaculture systems for over one year

• Published in: Canadian journal of zoology Vol. 99; no. 11; pp. 984 - 994
• Main Authors: Fang, Yuanchang, Emerman, Joshua D, Chan, Victor K.S, Stiller, Kevin T, Brauner, Colin J, Richards, Jeffrey G
• Format: Journal Article
• Language: English
• Published: 1840 Woodward Drive, Suite 1, Ottawa, ON K2C 0P7 NRC Research Press 2021; Canadian Science Publishing NRC Research Press
• Subjects: Aquaculture; aquaculture en parc clos; Atlantic salmon; Body mass; Cataracts; closed containment aquaculture; coho salmon; conditions ambiantes optimales; Conversion ratio; Feed conversion; Freshwater fish; gonadosomatic index; indice gonadosomatique; Maturation; maturation précoce; Oncorhynchus kisutch; optimal environmental conditions; osmoregulation; osmorégulation; Physical growth; precocious maturation; RAS; Salmo salar; Salmon; Salmoniformes; SAR; saumon atlantique; saumon coho; Seawater
• ISSN: 0008-4301; 1480-3283; 1480-3283; 0008-4301
• DOI: 10.1139/cjz-2020-0288

There is increasing interest in defining optimal conditions for rearing salmon to market size in recirculating aquaculture systems (RAS). Salinity, however, as a parameter that can be potentially manipulated, has been poorly studied. To address this knowledge gap, we reared coho (Oncorhynchus kisutch (Walbaum, 1792)) and Atlantic (Salmo salar Linnaeus, 1758) salmon from smolt to market size over ∼460 days at five different salinities (0, 5, 10, 20, and 30 ppt) and examined their growth performance. We found that both species reared at intermediate salinities (5–10 ppt) started to show significantly larger body mass than fish reared either in freshwater or full-strength seawater at around days 250–300. These growth-enhancing effects were maintained until day 460. The higher growth in Atlantic salmon at intermediate salinities was associated with a reduced economic feed conversion ratio, but this was not observed in coho salmon. The all-female coho salmon showed no incidence of sexual maturation and negligible cataract formation, while the mixed-sex Atlantic salmon showed high levels of sexual maturation (up to 50%) and presence of cataracts (up to 60%). Our results indicate that all-female coho salmon may be better suited to RAS than Atlantic salmon in some aspects. However, in both species, long-term rearing at intermediate salinities improved growth in RAS.