Genetic Escapes

Genetic escapees are fish or invertebrate species that are non-native, or have been selectively bred or genetically modified, and have escaped from mariculture enclosures.

Escapees pose a threat to ecological and socioeconomic stability as they may cause “biological pollution” within an ecosystem. Non-native species, if accidentally released, may compete with or prey upon native species, eventually driving them to extinction. Even if native species are cultivated, they are often bred to emphasize traits that may outcompete local wild populations, including disease resistance, high growth rate, and decreased spawning activity. The release of these modified breeds may reduce the presence of native populations through competition or, if they interbreed, by diluting the native genotypes, or by causing the spread of foreign parasites.

Improving standards for containment methods, limiting the cultivation of exotic species, and restricting mariculture to sterile populations may effectively minimize the risk of genetic escapes.

Which Goals Does This Affect?

Coastal Livelihoods
& Economies

Food
Provision

Biodiversity

How Was It Measured?

Genetic escapes represent the potential for harmful genetic escapement based on whether the species being cultured is native or introduced. Data came from the Mariculture Sustainability Index (MSI), which reports data for 359 country-species combinations (53 countries represented). In the MSI analysis, negative species received the highest score (10), while foreign and introduced species received the lowest (1), based upon the premise of potential impacts to local biodiversity if these species were to escape. Uses of native but non-local species were scored intermediately, based upon the assumption that potentially negative alterations to genetic biodiversity can occur from non-local sources, but to a lesser degree. Where multiple scores exist for a country the weighted average of all scores (0-10) was used. All country scores were rescaled from 0 to 1, using the maximum raw score of 10 and minimum of 1.

See Raw Data

What Has Been Done?

Increased Standards Lead to Decrease in Escapes

In 2004, the Norwegian government introduced a new technical standard, NS 9415, which increased standards for aquaculture equipment to help prevent escapes. While the population of farmed salmon has increased since 1994, the number of escapes from salmon farms has dramatically decreased since the implementation of the new standard (Jensen et al. 2010).

References

Beardmore, John A. & Porter, Joanne S. Genetically Modified Organisms and Aquaculture. 40 (Food and Agriculture Organization of the United Nations: Wales, United Kingdom, 2003).

Bekkevold, D., Hansen, M. M. & Nielsen, E. E. Genetic impact of gadoid culture on wild fish populations: predictions, lessons from salmonids, and possibilities for minimizing adverse effects. ICES J. Mar. Sci. 63, 198–208 (2006).

Hindar, K., Fleming, I. A., McGinnity, P. & Diserud, O. Genetic and ecological effects of salmon farming on wild salmon: modelling from experimental results. ICES J. Mar. Sci. 63, 1234–1247 (2006).

Jensen, Ø., Dempster, T., Thorstad, E.B., Uglem, I & Fredheim, A Escapes of fishes from Norwegian sea-cage aquaculture: causes, consequences and prevention. Aquaculture Environment Interactions 1, 71–83 (2010).

Skaala, Ø., Wennevik, Vidar & Glover, Kevin A. Evidence of temporal genetic change in wild Atlantic salmon, Salmo salar L., populations affected by farm escapee. Journal of Marine Science 63, 1224–1233 (2006).

Statistics Norway. 378 Fish farming. Stocks and loss of fish due to escape and disease. Salmon and rainbow trout. 1 000. (2011).

Trujillo, Pablo A Global Analysis of the Sustainability of Marine Aquaculture. (Resource Management and Environmental Studies: University of British Columbia, 2007).

Trujillo, P. Using a mariculture sustainability index to rank countries performance, In: Alder, J. and D. Pauly (eds.) A comparative assessment of biodiversity, fisheries and aquaculture in 53 countries’ Exclusive Economic Zones. Fisheries Centre Research Reports. (Fisheries Centre, University of British Columbia, 2008).