Krill is a keystone species. Lose krill and the food chain collapses — at least krill is thought to hold such a role in the Southern Hemisphere. There, it is harvesting for omega 3 supplements that’s causing the decline. https://www.theguardian.com/environment/2008/mar/23/fishing....
I think mostly the krill is used as fish and animal feed as a source of protein. Supplements are probably a small part of the consumption.
It seems like a bad idea to overfish the base food chain species. But then pretty much everything we do with the ocean is a bad idea.
The only thing that has been positive where the oceans are concerned is creating marine reserves where commercial fishing is prohibited, and enforcing that.
