Genetic Escapes

'Genetic escapes' are plants or animals that are either not native to an area or have been selectively bred or genetically modified and have escaped from mariculture enclosures.

Escapes pose a threat to ecological and socioeconomic stability if they compete with or prey upon native species.

Even if native species are cultivated, they are often bred to emphasize traits that could reduce the fitness of wild populations if escapees interbreed with wild specimens.

Escape of non-native species could also introduce foreign parasites into the local ecosystem. 

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?


How Was It Measured?

Measurement of the potential for harmful genetic escape was based on whether the species being cultured is native or introduced. Data came from the Mariculture Sustainability Index (MSI), which reported data for 359 country-species combinations (53 countries represented). In the MSI analysis each species  grown received a score from 1 to 10.  Low scores indicate lower potential for ecological harm.  Native 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. Native but non-local species received intermediate scores, based on the assumption that they could negatively affect local genetic biodiversity but to a lesser extent than foreign or introduced species.  In regions where multiple species are grown, each species was scored and the yield- weighted average of all scores was used. Scores for all regions were then rescaled from 0 to 1, using the maximum raw score of 10 and minimum of 1.

All pressures are ranked for their differing affects on different goals. For each goal, the effect of each pressure is weighted 'low' (1), 'medium' (2) or 'high' (3). The actual data-derived value of the pressure is then multiplied by the weight assigned to it for that goal. That process is repeated for each pressure-goal combination.  The sum of those values divided by 3 (the (the maximum pressure-goal value) expresses the total affect of pressures on the goal.

Genetic escape affects three goals, Food Provision (Fisheries), Livelihoods & Economies (Commercial Fishing) and Biodiversity (Species). Its impacts on all of them are low (weight = 1).



What Has Been Done?


References




PHOTO(S): © Keith A. Ellenbogen
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