About half of this comes from forage fish, such as anchovies, while 53 percent now comes from aquaculture and fisheries byproducts
The review led by Dr Brett Glencross, along with a team of renowned fish and human nutrition experts, explains how long-chain omega-3 polyunsaturated fatty acids (LC-PUFAs) like eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA) have a wide range of effects both on fish and human physiology: cell membrane structure, regulation of inflammation and disease resistance.
Key findings
- Current estimates of EPA and DHA production are around 160,000 tonnes per year, with more than 90 percent of this coming from fishery and aquaculture resources:
- Estimates of global fish oil production are around 1.2 million tonnes per year with an increasing contribution of by-products from various fisheries and aquaculture (53 percent). Among these oils, EPA and DHA can make up from <2 percent to almost 60 percent of the total fatty acids.
- Aquaculture is a net producer of EPA + DHA relative to its inputs and a greater contributor to human EPA + DHA supplies than the direct consumption of wild fish.
“Among the aquaculture sectors that are the largest users of LC-PUFA resources (salmonids, shrimp, and marine fish), there are varying degrees of capacity by each to synthesize LC-PUFA: this affects the degree to which they must be obtained via the diet,” Glencross explains.
Limited capacity for additional growth
Prospects for expanding the volumes of available EPA and DHA are limited and include:
- Improvements in circular-resource thinking. The scale of the losses of the omega-3 LC-PUFA resources through food wastage alone is equivalent to about 50% of that consumed. The model used by the scientists in this review estimates that a total pool of 272 ktonnes of EPA + DHA is available from the combined unutilized by-product resources.
- The development of other sources of these fatty acids, including those produced from zooplankton, algae, and genetically modified (GM) plants. So far though, only algal oils contribute any significant volume, with an estimate of 12,000 tonnes for 2023.
Knowledge gaps
“Much remains to be done to both improve the understanding of the physiological roles of omega-3 LC-PUFA in aquaculture species and better define their requirement for the myriad of species now being farmed in aquaculture,” Glencross states.
For instance, the prior nutritional history of an animal and how this affects subsequent requirement responses have not yet been examined. Additionally, dietary formulation strategies have changed significantly over the last decades and should be considered to determine intake levels of all the nutrients needed by the fish. Finally further research is needed to elucidate the multi-faceted role that it is likely that LC-PUFAs play, including interactions among the different PUFAs.
