I have to admit that I'm not very familiar with the Norwegian data you've referenced. What I will say is that humans have been culling or conducting predator control of pinnipeds for at least a hundred years, yet there's not a single scientific study or any evidence that it has ever benefited fish stocks. If you have one, I would like to see it. However, from my review of the scientific literature, I have not come across that. I think that says something.
Even studies, for example, on the southern Gulf of St. Lawrence cod, where they said a 65% reduction could prevent the local stock from going extinct, clearly specified that there is the potential for unintended consequences. It did not address that. That's just a very common feature of the discussion about significant reductions in pinniped populations to benefit a fish stock. We simply cannot predict the outcomes of those actions.