Genetic diversity in fish is generally less compromised than in farmed plants and animals, partly because a little over half of fish consumption is still from the wild capture fishery, and partly because the domestication of fish in industrial aquaculture is relatively recent, since the mid-20th century (see Saraiva et al., 2019), though traditional and more ecological aquaculture has been around for millenia. There are of course many threats to wild fish populations and these forces are mostly addressed elsewhere (see Goal 5 Sustainable fishery management) Two things addressed here are: a) fish stocking for wild populations to assure genetic diversity in wild populations; b) genetic manipulation of stocks for aquaculture.
A wider range of species are farmed than in agriculture and because of a short period of domestication, the variability found in wild populations still mostly exists in cultured ones. But Saraiva et al. (2019) adapt the 5 levels of domestication (see Introduction) to farmed fish and find that Common carp, Nile Tilapia, Gilthead seabream, European seabass, Atlantic salmon, rainbow trout, and Siberian sturgeon are already at the highest level of domestication.
Only 23 species comprise 75% of aquaculture global production and North America uses the smallest number of aquatic species of any region of the world. A large number of species used in aquaculture are non-native to their country of production (FAO, 2019), although this is less the case in Canada, where most species used are native. All this is both positive and negative, in that fewer species at this stage face the pressure of domestication. But the worry is that aquaculture will follow the same process that has narrowed the genetic base in agriculture, so whatever species are used in aquaculture will suffer over time comparable kinds of genetic decline. Can governments and industry act now to avoid such an outcome?
Canada's regulatory system for fish genetic resources (aquaculture)
Fish genetic resources (AqGR) are not directly regulated in Canada, but numerous policies, acts and regulations have some bearing on AqGR. Aquaculture regulation is primarily undertaken by Fisheries and Oceans Canada, with licensing provisions for businesses administered by the provinces, including the capture of fish for stocking and hatchery, and stocking operations (see Goal 5 Sustainable food and aquaculture). As part of their effort to protect wild stocks, FOC is also responsible for regulating fish with novel traits (e.g., genetically engineered fish and triploids [infertile fish] used to stock catch and release fisheries or aquaculture, see Goal 4).
Under the Health of Animals Act (Health of Animals Regulations and Reportable Disease Regulations), the CFIA has regulatory authority for limited disease in aquatic organisms. Canada also has a National Code on Introductions and Transfers of Aquatic Organisms which is designed to manage diseases and invasive introductions, all of which can have negative impacts on aquatic genetic resources. The code is applicable to the federal, provincial and territorial governments.
The Species at Risk Act (SARA), proclaimed in June 2003, has some pertinence as all three wolffish species (the Northern, Spotted and Atlantic), and the American Eel are listed as at risk under SARA. See Goal 5, Wildlife Protection and Species at Risk.
Current approaches to protecting genetic resources: strengths and weaknesses
According to the FAO (2019), protecting fish aquaculture genetic resources is less developed and co-ordinated at an international level than the system for farmed plants and animals. Data on many aspects of aquatic resources are weak, particularly for plants and microorganisms in aquaculture.
As with animal genetic resources, there are in-situ and ex-situ strategies (FAO 2019). In-situ is preferred as a conservation strategy but difficult to identify in some ways in aquaculture, especially to distinguish it from ex situ in vivo conservation. In contrast, for wild populations, aquatic protected areas (sometimes multi-use, sometimes conservation habitat only) are widely used to conserve AqGR in situ. About 1% of Canada's oceans are protected to various extents through 797 marine protected areas, 705 managed provincially, 83 federally, and the remaining nine by either non-governmental organizations or co-management arrangements (Fisheries and Oceans Canada, 2016).
Ex-situ in vivo involves keeping breeding stock on site, primarily for genetic improvement in a farmed environment rather than wild population conservation. Aquaria, zoos and botanical gardens are sometimes used but have limited application. Ex situ in vitro conservation is currently only possible for male gametes, micro-organisms and early stages of mollusc development, and not practical for eggs or most embryos.
Canada reports (Fisheries and Oceans Canada, 2016) that the use of genetic data in aquaculture is low. Genetic resources are not generally sourced from wild seed or wild stock. Almost all breeding work is undertaken by the private sector, with no government selective breeding programs though some private ones may benefit from public grants. Genetically improved aquatic organisms, including hybrids, crossbreeds, strains, triploids and other distinct types are a major part of aquaculture production, especially in Atlantic salmon, rainbow trout, arctic char, and scallops. However, there remain problems with many of these "improved" organisms. For example, triploids (infertile) are promoted as a way to reduce chances of farmed fish breeding with wild species, but they are not always popular in the aquaculture sector because their performance appears to be compromised relative to regular diploids (fertile).
There is some in vivo gene banking as Fisheries and Oceans Canada has facilities for endangered units of Atlantic salmon on the east coast (inner Bay of Fundy), and propagates strains of Pacific salmonids in its west coast hatcheries for wild stock enhancement and research. Aquaculture needs are not a priority of these activities. However, hatcheries for salmonid enhancement are controversial, with a significant amount of evidence that they are actually contributing to genetic erosion in wild stocks. Hatcheries have been used for over 100 years in North America, as tools to compensate for our inability to manage for loss of habitat and overfishing, but it appears they have been ineffective. This occurs because the hatchery rearing environment generates young that are less "fit" in wild environments and when they mate with wild species contribute to a reduction in overall stock fitness and survival, effectively then enhancing short term harvest opportunities at the expense of long term survival (cf. Araki et al., 2009; Chilcote et al., 2011; Christie et al., 2012; Christie et al., 2014; Hatchery Scientific Review Group, 2009; Saraiva et al., 2019).
According to Fisheries and Oceans Canada (2016), only to a limited extent are collectors of wild seed and brood stock for aquaculture and culture-based fisheries contributing to the conservation of aquatic genetic resource. Canada has exchanged genetically altered Atlantic salmon, rainbow trout and tilapia embryos with the USA and imported from the US living specimens (no deliberate genetic manipulation) of Japanese scallops and Pacific oyster. FOC claims that federal policy enables qualified researchers and breeders anywhere in the world to have unrestricted access to genetic resources in Canadian gene banks for research and breeding. However, Canada has yet to sign the Nagoya Protocol on Access to Genetic Resources and the Fair and Equitable Sharing of Benefits Arising from their Utilization to the Convention on Biological Diversity, and this places in question the integrity of the claim.
A main focus of the department's work on genetic diversity appears to be the use of genomics to characterize the differences between wild and domesticated stocks and to monitor possible genetic erosion in wild stocks, part of the National Aquatic Biotechnology and Genomics Research and Development Strategy. While this is important, it is not per se a program to protect genetic diversity, especially when contrasted with their biotechnology focus in aquaculture that appears to be similar to what's happened in animal agriculture, using breeding technologies to increase growth rates and overall size of fish species (DFO). In other words, much of their research is about developing high performance genetics.
Overall, the FOC (2016) acknowledges the weakness in the Canadian system. In its report to the FAO, it effectively identifies a high priority need to Improve capacities for conservation of aquatic genetic resources.