In August of last year (2022) we reported about kelp being produced to – indirectly – feed salmon with omega-3-rich food. In this case, the humble ragworm was used as an intermediary: the ragworms fed on kelp, producing omega-3 fatty acids, and the ragworms were then fed to the salmon.
In a new publication, Napier and Betancor discuss the use of genetic engineering of plants used as sustainable feedstock in aquaculture. The existing challenge is that, while aquaculture delivers key nutrients such as omega-3 long chain polyunsaturated fatty acids, it also relies on marine products as key feed ingredients, which can be adversely impact the ecosystems in the long run. There is the need to transition away from unsaturated oils derived from marine sources as feed ingredients and towards alternative supplies of these important fatty acids.
The authors postulate that the use of transgenic plant sources containing these fatty acids could present an alternative to fish oils in aquafeed diets. Two plant candidates have been identified for this endeavour: Camelina and Canola. Recently, gene editing has been used in conjunction with transgenesis to enhance the accumulation of EPA DHA in Camelina via the inactivation of a competing endogenous pathway to achieve the production of polyunsaturated fatty acids. Also, Brassica species (canola) has been identified as excellent hosts for the transgenic accumulation of omega-3 polyunsaturated fatty acids and the oils derived from these crops have been used in multiple aquafeed trials. The performance of these crops has also been demonstrated in ﬁeld trials on different continents.
Based on this review, genetically engineered crops accumulating high levels of polyunsaturated fatty acids have a high potential to become sustainable aquafeed ingredients in the future, lessening the impact on marine environments.