[alecthomas]

This paper [1] (PDF) indicates it is likely a complex interaction between multiple parts of the ecosystem. One example is that large cod are apex predators, competing with seals and when those cod were removed, seal populations increased, and predation on small cod increased correspondingly.

[1] https://oceansfirstjournal.files.wordpress.com/2016/08/ocean...

[morkalork]

Thanks, that was surprisingly interesting. It also talks about capelin the sibling comment mentioned.