[user104658]

Originally Posted by arista

Sadly, they are looking for fish
but go out of range into warm waters

That’s not wot is sez arista.

It says the fish they eat (sardines and anchovies) prefer colder water, and because the water is getting warmer, the fish are settling deeper in the water (as it’s colder the deeper you go) and they’re now too deep for the penguins to get to them as they can only dive to about 30m. So basically the fish are still there - but the penguins can no longer reach them.

It’s quite a good illustration of how even a tiny change in average temperatures can disrupt a food chain.