People cutting back on seafood--moving to livestock
I would not be surprised to hear fish stocks in the worlds oceans are coming under pressure from a variety of reasons including over fishing. Given that fish is a relatively cheap source of protein for many nations, we might see an increase in fish farms. Fish farms use ag feeds to grow the fish crop.
I would add that i have seen some documentaries that indicate fish population/catch declines in several areas of the ocean, but i dont know about the over all big picture. So i say i would not be surprised to hear fish populations world wide are under pressure/decline. In fact i think this is the case. So we have a growing world population while a decline in fish population/catch. This is a condition for increased fish farming or switch to other proteins based on feeding from ag crops.