In the ocean, more and more schools of fish are decreasing in number. They will become unprofitable to fish before they become extinct, but either would be a disaster for both the fishing industry and the people that this feeds.
What if we bred common fish in saltwater tanks, tanks that occasionally flushed to the sea? This could improve the wild stock's genetic diversity, increase their numbers, and stabilize the fishing stock. We feed them on cheap things while they're in the tanks, thereby building up the ocean's biosphere.
Also, hypothetically, information is biology. Having complete knowledge of an organism's genome allows you to create one. We could make many variations of fish in the tanks, and see how they work out before introducing them to the wild. Traits like fast growth, large growth, and rapid reproduction would keep the wild stocks in better shape. They would likely breed into the wild population.
Funding is the key. Maybe some of the stocks could be sold to the market instead of flushing out to sea, maybe this would be a government conservation project, publicly funded.