Pacific Coho marine survival in the Strait of Georgia (SOG) has declined from 10% in the 1980’s to approximately 1% in recent years. Several approaches have been taken to gather data to help explain this decrease. This project would look at factors affecting wild Coho health as a possible contributing factor.
Two common salmonid pathogens are Renibacterium salmoninarum (causative agent of Bacterial Kidney Disease – BKD) and Vibrio anguillarum. The treatment of these two diseases differs in the approach taken. BKD needs to be identified in broodstock to help prevent the passing of bacteria to progeny and Vibrio infection is best prevented with immunization.
The first portion of the trial is to determine the occurrence of Bacterial Kidney Disease in Coho broodstock. By testing each Coho for BKD levels, a baseline infection rate can be established. While regular sampling for BKD exists, a screening of all broodstock in a year class has not been undertaken before.
The second objective of the trial is to do intraperitoneal (into body cavity) injections against Vibrio in a group of pre-smolt Coho held in freshwater at Quinsam Hatchery in Campbell River, BC. It is hypothesized that Coho would be better protected against V. anguillarum in the marine environment and this would reduce early marine mortality, potentially an important factor in reduced survival rates to adult return.
To establish health of the fish before vaccination, numbers of pre-vaccinated fish would be tested for two common diseases that can be found in freshwater; BKD (by qPCR) and furunculosis (causative agent Aremonas salmonicida). The health check would be repeated pre-release. Vaccinated fish are marked with Coded Wire Tags and survival will be monitored at the hatchery. The project would be repeated for 5 years so a significant amount of return data can be established.