It's a bird! It's a plane! It's...a krill SUPERSWARM!

As a "low-trophic level" species, krill get a lot of attention. They're at the base of the food web, so scientists have to know what drives them to be able to understand the rest of the ecosystem. Krill tend to group together in huge swarms, but the swarms very in size, with some so large they are considered superswarms (sounds almost ominous, doesn't it?). Superswarms are bigger and more dense than normal swarms, and are at least 1 km long and 30 m deep. Notice I said at least - some are 10 kilometers long! Superswarms are thought to account for the majority of the entire biomass of krill in the Southern Ocean, meaning that 60-70% of all krill could be represented by 10 or so swarms. A new study by the British Antarctic Survey, reported by the BBC, claims to have discovered some (but not all) of the secrets of the superswarms. Some highlights:

-Superswarms are made up of juvenile krill. Adults form smaller, less dense swarms.

-Superswarms are more likely to form when there is less food.

-Superswarms are more likely to form at night.

The researchers posit that because juveniles need to eat less, the protective benefits of swarming with billions of other krill outweigh the negatives of having more competition for food. More urgently, however, the research points to the need to manage krill fishing cautiously. If most krill are concentrated in just a few swarms, fishing from the largest swarms could have a greater impact on krill populations and krill predators than previously thought - even if catches aren't a large proportion of the estimated overall population. ASOC has been encouraging CCAMLR to subdivide the krill catch among several geographic areas to ensure that harvests are evenly distributed. Hopefully this study will provide more momentum for that effort!