Effects of Ultraviolet Radiation (UVR) on Fin Health in Pacific Salmon

Description

Most salmon aquaculture facilities rear fish in indoor tanks or in outdoor tanks covered to reduce levels of natural light. While this is usually done to reduce aquatic plant growth or to discourage predators, it is known that natural lighting can be important in the rearing of fish. A frequent complaint from indoor fish culture operations however, is the presence of severely abraded fins. Fin erosion is normally attributed to aggressive interactions between fish and/or physical contact with the walls in over crowded tanks. We now have a new explanation for this common phenomenon in aquaculture facilities that renders fish unattractive to discerning buyers and negatively impacts public acceptance of these fish - the absence of sufficient exposure to ultraviolet radiation (UVR).

While we have consistently observed that exposure to UVR prevents the physical deterioration of the fins of juvenile coho salmon in fresh water, we do not know the amount of exposure required to maintain fin health. This is important because excessive amounts of UVR can have detrimental consequences. We also need to determine if it is possible to remediate damaged fins by subsequent UVR exposure. The potential for use of artificial UV sources for prevention and remediation must be evaluated. The physiological mechanism involved in UVR-fin development needs to be elucidated.

Program Name

Aquaculture Collaborative Research and Development Program (ACRDP)

Year(s)

2007 to 2010

Ecoregion(s)

Pacific: Vancouver Island West Coast

Principal Investigator(s)

L. Blair Holtby
Email: HoltbyB@pac.dfo-mpo.gc.ca