Omega-3 nutraceuticals, climate change and threats to the environment: The cases of Antarctic krill and Calanus finmarchicus

The nutraceutical market for EPA (eicosapentaenoic acid) and DHA (docosahexaenoic acid) is promoting fishing for Euphasia superba (Antarctic krill) in the Southern Ocean and Calanus finmarchicus in Norwegian waters. This industry argues that these species are underexploited, but they are essential in their ecosystems, and climate change is altering their geographical distribution. In this perspective, we advocate the cessation of fishing for these species to produce nutraceuticals with EPA and DHA. We argue that this is possible because, contrary to what this industry promotes, the benefits of these fatty acids only seem significant to specific population groups, and not for the general population. Next, we explain that this is desirable because there is evidence that these fisheries may interact with the impact of climate change. Greener sources of EPA and DHA are already available on the market, and their reasonable use would ease pressure on the Arctic and Antarctic ecosystems.

A warming Southern Ocean may compromise Antarctic blue whale foetus growth

After declining in abundance due to commercial whaling during the 20th Century, populations of the Antarctic blue whale (Balaenoptera musculus intermedia) have failed to recover to pre-exploitation levels. Using historical whaling data from 1926-1954, in combination with temperature data for the Southern Ocean, a gamma GLMM with temporal dependency was fitted to 20,144 records of B. m. intermedia foetus size using Bayesian inference. There was a negative relationship between antecedent winter sea surface temperature (SST) in the Southern Ocean on foetus size. This relationship is proposed as being mediated by a positive effect of the extent of winter sea ice on Antarctic krill (Euphasia superba) abundance on which B. m. intermedia feed. There was also a positive density-dependent effect of a ‘krill surplus’ at low whale population sizes. However, the positive effect of a ‘krill surplus’ at low B. m. intermedia population size on foetus growth was reversed at elevated winter SST due to a negative impact on E. superba recruitment. Projected increases in temperature in the Southern Ocean are predicted to compromise the growth rates of B. m. intermedia foetuses, with implications for the capacity of the subspecies to recover from overexploitation.