For Earth Day 2016, I wrote about how growth of palm oil plantations has removed habitat for many tropical species, and that plantations are expanding globally as demand for cheap oil increases. But if demand for these cheap oils does not decrease, what other sources are available? Some consider krill oil a potential replacement or new renewable oil source particularly for human supplements.
What is krill?
Krill is a general term for the 100+ species of invertebrates in the order Euphausiacea. Krill are incredibly important because they form the base of many marine food webs. They are omnivorous but mostly eat phytoplankton and algae, thereby getting nutrients from these primary producers into marine food webs. Krill often forage under sea ice or at the sea surface, making multiple daily migrations up-and-down the water column to feed and rest. Krill then become food for birds, fishes, seals, and whales. Further, their feces sink and provide a carbon source for ocean floor dwelling detritivores. Scientists estimated that the Antarctic krill (Euphausia superba) alone has an annual biomass between 342-536 million tons! Given both the large biomass and important ecological role, krill are a keystone species in the ocean.
People began fishing krill in the 1970s. In 1982 the Convention for the Conservation of Antarctic Marine Living Resources was established in part to protect Antarctic krill and other species from over-harvest. The FAO reported that 316,000 tons of krill were harvested in 2014 with an increasing trend in annual amount harvested. Once harvested, krill is dehydrated after which it has a high protein content (40-80% of dry weight). The dehydrated product is then turned into fishing bait, aquaculture feed, and human food (direct krill products and omega-3 oil supplements). Krill is difficult to harvest because it is so small (<6cm) thus needs a very fine mesh net which has high drag; however, technology for harvest and on-boat processing is improving and expected to increase yields in the future.
The increasing harvest of krill (even though it is less than harvest limits) has intersected with climate change, thereby decreasing the amount of krill in the oceans. Specifically, sea ice loss during the winter both decreases areas to forage and places to hide from predators. Ocean acidification is another concern. In an experiment on larval krill, scientists observed that increasing dissolved CO2 disrupted larval development. Additionally, the krill exoskeleton contains carbonate which dissolves under acidic conditions. Scientists project that Arctic ecosystems may be resilient to krill loss due to the ability for changing species composition which maintains trophic balance in food webs. However, Antarctic systems do not appear to have this resiliency due to strong temperature gradients which may exclude new species from entering the ecosystem.
Thus as krill decrease, there are fewer food resources supporting marine mammals and sea birds. It’s in this way that krill may be the new palm oil. As demand for cheap products increases, krill is harvested or palm plantations are planted; thereby removing the support system from the bottom of each ecosystem. We’ve seen the cascading effects related to palm plantations. Now the question is, will we observe similar cascades in marine ecosystems? In 2009, the US banned krill fishing off the Pacific coast to protect the animals that feed on krill, including endangered species. So krill conservation is not really about krill, it’s about all the cute things (e.g. penguins, blue whales, etc) that need krill to survive. This is another similarity with palm oil, as opposing the product is mostly about loving orangutans! But these specific conservation issues require us to see the whole ecosystem (especially from the bottom up), and not just the megafauna at the top.