Omega-3 (Docosahexaenoic acid -DHA- and eicosapentaenoic acid -EPA-) provides benefits on health for humans and animals in general. EPA and DHA are essential for proper fetal development and healthy aging. Global recommendation for these two acids intake is around 500 mg day for adults and 250 mg day for infants. Considering the 2020-year world inhabitants (7.7 billion) we can estimate around 1.23 million tonnes of omega-3 global requirements.

Currently, the supply of these acids is coming from wild and cultured fishes and other sea products (e.g. algae and molluscs). Once we discount the aquaculture demand for fishmeal and therefore, for omega-3, we can stablish that around 86 % of these omega-3 necessities are covered. Based on our own estimates, fishmeal and algae wild production provides the 69 % of current omega 3 supply and cultured production 31 %.

In this situation of net deficit, considering that wild traditional fisheries catches cannot be increased, and that this net deficit is likely to increase due to the world population growth, the mesopelagic fishes provide an opportunity to produce omega-3 rich fatty acids. This is because mesopelagic fishes are rich in lipids. Approximately, half of their dry matter are lipids and between 10 to 20 % (depending on the species) of these lipids are EPA and/or DHA.

Mesopelagic fishes’ high abundance estimates present an opportunity to reduce the differences between omega-3 requirements and supply of these essential fatty acids. At around 10.000 million metric tonnes of total biomass, a 0.5 % harvest rate and using the latest acids composition of the mesopelagic species, could cover between the 30 % to 80 % of the omega-3 necessities or around 27 % to 71 % if the energy transfer necessities through the trophic chain are considered (the range is based on the big uncertainty on the lipids and DHA-EPA contents of mesopelagic fishes, and the differences between species).

Therefore, only from the omega-3 point of view, mesopelagic fishes provide an opportunity to inflate the blue growth economy through, for example, the expansion of cultured fishmeal production. They are also a source of protein and furthermore, an option for new pharmaceutical, nutraceutical products development and as DNA sequences. These opportunities are based on current and future markets and will therefore have to compete with other omega-3 natural sources (e.g. algae and bacteria) or other uses (biofuels). Also considering costs and consumer preferences and attitudes.

A question from the SUMMER project is: what are we trading off by fishing this 0.5 %? Currently, the unexploited mesopelagic layer is providing supporting services (nutrient regeneration and cycling), cultural (charismatic species support), regulating services (Diel Vertical Migration and its influence in the carbon pump), and also provisioning services by increasing the ecosystem resilience and ensuring provision of other (commercial) species. These services can be altered by starting a commercial fishery of mesopelagic, aiming to supply omega-3 for humans (directly or through cultured fish) or any other nutraceutical and/or pharmaceutical product.

The mesopelagic ecosystem can provide possibilities from a human wellbeing point of view that this is characterized by the services (known and unknown) that the ecosystem is currently providing. Therefore, we consider that this is the last chance to do things right. Let’s explore the benefits and the trade offs and inform managers to help them take well informed decisions.

Text by: Raúl Prellezo, AZTI