Aquaculture  - Biotechnology topics

Canada’s Fish Health Protection Regulations are designed to reduce the risk of fish pathogens spreading to new areas. The regulations require an import permit to bring live salmonids (fish of the Salmonidae family: salmon, trout, charr and whitefish), their eggs, or the eggs of wild salmonids, into one province from another or into Canada from another country. The commercial, recreational, research, and aquaculture sectors move live fish or their eggs from one water body to another.

Obtaining a transfer licence requires certification that the source of the fish or eggs has been inspected and is free of infectious diseases of concern to the importing waters. The Fish Health Protection Regulations, therefore, allow for transfers of salmonids or their eggs, if their pathogen profile matches that of the recipient area. The idea is that, if the pathogen is already present in the new area, there is no point barring the import of live salmonids or eggs just because they have the same pathogen. This is called the "like-to-like" policy.

What is the issue?

While a species of a pathogen may be the same in two areas, it may not be the same strain – i.e., have an identical genetic composition or infectious capability. It is, therefore, important to determine and define "similar" pathogens, in order to accurately assess their risk to fish under culture in different regions of the country, as well as from outside Canada. The first step is to gather information about the genetic makeup of fish pathogens. And researchers from Fisheries and Oceans Canada (DFO) are doing just that.

The research plan

In this three-year study, DFO researchers will look at seven microorganisms:

- two viruses

i) viral haemorrhagic septicemia virus (VHSV) and

ii) infectious haematopoetic necrosis (IHNV)

- two bacteria

i) bacterial kidney disease (Renibacterium salmoninarum) and

ii)Furunculosis (Aeromonas salmonicida)

- three parasites

i) PKX myxosporean,

ii) Nucleospora salmonis and

iii) Kudoa thrysites.

These were chosen because they are important salmonid pathogens. Some are present in both Atlantic and Pacific Canada, and some may be transmitted with eggs.

Researchers will collect representational samples of these pathogens from a wide range of areas to be studied at the biomolecular level. They will use the molecular genetic information they gather to map out gene patterns from the microorganisms from different areas. This will help them focus on areas of the genetic code that reveal differences within the same species, and map out any differences, if they exist, between samples from different parts of the country… or world.

Once the scientists have this information, they can analyse the physical characteristics that develop in the pathogens as a result of their interactions with their environment. These studies will assess and compare the capacity of the various strains of each pathogen to infect salmonids, alternative, or carrier (non-diseased) hosts, in different areas.

Benefits of this research

The results of this research will be important in:

preventing the transfer and establishment of strains of important salmonid pathogens into areas where they do not now occur in Canada;
providing greater accuracy in health risk assessment of security in the salmonid aquaculture, commercial, and recreational fisheries sectors; and,
increasing knowledge about salmon pathogens, their infective dynamics, the potential impact of environmental factors on them, and their geographic / host species distributions.