Breeding strategy and early rearing environment affect the immune response in Chinook salmon (0ncorhynchus tshawytscha).

BECKER, LA; HEATH, JW; HEATH, DD; DIXON, B

Waterloo, Ontario, Canada

Workshop; Canadian Comparative Immunology and Pathology Workshop; 2010

University of Waterloo

Salmon aquaculture practices are fundamentally based on artificial mating, which in time can lead farmed stocks to diverge genetically and phenotypically from wild fish. In this context, the fish immune system can also be affected and is of extreme importance for commercial fish production. The work presented here aims to increase our general knowledge of the biology of this species by taking an immunological approach. A disease challenge using Vibrio anguillarum was performed on four groups of fish which combined two different breeding strategies (artificial vs. semi-natural) with two rearing environments (indoor artificial tanks vs. outdoor gravelled channels). Results including mortality rates and MH class II β1 genotyping indicate that fish immune responses are affected by breeding strategies and early rearing environments. In particular, differences in mortalities are accentuated in artificially-spawned fish, while semi-naturally-spawned fish does not seems to be severely affected by different rearing environments. Moreover, there are no clear associations of survival or mortality to particular alleles or genotypes of the MH class II antigen-presenting molecules. Gene expression analysis employing a 700-gene chip cDNA microarray on samples from control and infected fish is currently being undertaken which will hopefully help to assess the fish immune response at the transcriptome level. The use of semi-natural spawning procedures may improve the quality of the farmed fish by providing them with a better chance to face diseases in spite of environmental changes.