[Europan Ocean (OP)]

Do fish in icy waters move slower than fish in hotter waters?

Looking at metabolic rates... how does it work?

[Rasull]

Fish don't have to breathe as fast in cold water because their metabolism has slowed down and simply doesn't require as much oxygen. Furthermore, cold water contains more dissolved oxygen than warm water so they don't have to work as hard to extract the oxygen.

[evan_au]

Creatures take longer to reach maturity under these conditions.
So commercial fishing can't take many of the adult fish, as it takes a very long time for the young ones to reach maturity.