Yes, absolutely, but man's not a natural marine predator. The natural marine predators are integrated into perpetuating the life processes in the sea in a way that man is not. Man is a parasitic predator on the marine animals. The marine animals are interconnected, and the function of the ecosystem necessarily involves predation. Fish have been on the planet for 400 million years, never without predators. They're practically without predators now.
You pointed out that when there were fewer seals a few decades ago, the fisheries were healthier. That's true. There were more predators then because there were sharks and big hake and big cod. There were actually more predators.