Aquaculture  - Biotechnology topics

Aquaculture is rapidly expanding in Canada and around the world, as global demands for high quality protein increase and many wild aquatic resources are declining. Aquaculture has to the potential to meet both the need for increased fish and shellfish production, as well as reduce harvest pressures on wild stocks.

As aquaculture grows, however, there is an increasing need to diversify and bring new species into ‘domestication’. This parallels the agricultural experience where monoculture is a risky business (‘don’t put all your eggs in one basket’), as well as the fact that consumers appreciate diverse products to match their diverse tastes. One prime candidate for species diversification is the Canadian Atlantic halibut (Hippoglossus hippoglossus).

There are two general challenges in developing new species for aquaculture:

• designing a breeding program that will select desired traits while eliminating/suppressing undesirable traits; and
• avoiding inbreeding – as with any animal, mating between siblings or other close family members reduces genetic variation and can have disastrous health results. In halibut aquaculture, the inbreeding risk is high, because it is difficult to collect and condition the wild halibut needed to produce eggs for aquaculture. As a result, there is only a limited number of broodstock available to provide all the eggs required for commercial halibut production in New Brunswick and Nova Scotia.

Biotechnology can help meet these challenges. Scientists at Fisheries and Oceans Canada (DFO) are undertaking a research program to improve halibut aquaculture by using molecular biotechnology to help select the optimum broodstock. The goal is to identify the factors that improve healthy halibut growth, at the same time as avoiding inbreeding ‘bottlenecks’.

Researchers will map out the parentage and genetic background of halibut produced in recent breeding programs. To do this, they will analyze what are called ‘microsatellite markers’. These are small areas of the genetic makeup of a halibut that are variable and unique to that individual. These markers, therefore, provide a genetic ‘fingerprint’ that allows scientists to identify the offspring of specific parents.

Such tools help the aquaculture industry prevent inbreeding, since they can identify closely related individuals and those that are more distantly related (i.e., have different genetic profiles). This work also allows scientists to identify which parent crosses produce offspring with the best performance features for health and growth under aquaculture conditions. Researchers can then use this information to look more closely at inheritable variables, such as egg quality, parental condition and growth rates, to see if they can identify the genetic factors contributing to these traits in successful offspring.

This research is aimed at developing new, economically and environmentally, sustainable species for the aquaculture industry. This research should also:

• serve as a model for development of other species for aquaculture;
• increase understanding of good breeding practices in aquaculture; and,
• help reduce fishing pressures on wild halibut populations.