The effect of stressors on immunocompetence and susceptibility to Kudoa thyrsites as a measure of smolt quality


The Project has two objectives. The first is too determine whether the interval between the two stressors, intraperitoneal (IP) vaccination and saltwater (SW) entry (smoltification), affects the susceptibility of a populations to infection by (Kudoa thyrsites) and secondly to determine if different intervals between IP vaccination and salt water entry has a measurable effect on immune responsiveness. Immune responsiveness will be measured prior to SW entry and at two intervals post SW entry.

The experiment will be carried out using both the Cascade and Mowi stocks to determine whether differences in susceptibility and immune responsiveness occur between stocks of Atlantic salmon.

The experiment will consist of four different treatments plus a control for the stress of IP vaccination. The immune responsiveness of fish from each treatment will be measured prior to SW entry/challenge to determine whether the various intervals following IP vaccination has a measurable effect on the immune response. Immune responsiveness will again be measured on 10 fish from each treatment 96 hours and 3-4 weeks post SW entry to determine whether the added osmoregulatory stress of SW entry significantly affects the immune response.

The final report will provide the following information:

  • the importance of the number of accumulated thermal units (ATU's) post IP vaccination prior to SW entry on the susceptibility of the fish to Kudoa thyrsites will be determined;
  • whether differences in immune responsiveness can be measured as a function of the number of ATU's post IP vaccination prior to SW entry;
  • whether significant differences in immune responsiveness and/or disease resistance exist between Mowi and Cascade Atlantic salmon.

Project Start Date: April 01 2002
Project End Date: May 31 2004

Contact: Simon Jones (JonesS@pac.dfo-mpo.gc.ca)