There is a concern we have. When a salmon goes to sea, there's a big selection happening. Let's not kid ourselves. A lot of fish are dying, for a number of reasons, but it's not random. The fish that are coming back are the ones that have the right package to survive the conditions. They'll come back, spawn, and potentially pass that on to their progeny.
If you take the smolts and exclude the freshwater-and-marine cycle, a lot of them survive. All kinds of fish survive: the fish that have the right characteristics. Fish that would have the wrong characteristics survive in the ocean, but they survive, and they will spawn. That's what we want them to do. We want to raise them to adults, release them back to the river, and let them spawn.
We probably have fish that don't quite have the right fitness, but they are all spawning in the river. When they spawn in the river, they have juveniles, and juveniles will fight for space. There's only so much space in the river. They will compete with each other, and some die from that. We have a lot of unfit juveniles from less fit parents that are competing with fit wild juveniles, and some are dying, so then we have effects on the wild fish as well.
It's that issue about how the ocean is filtering the fish and letting the ones that have the right package come back and spawn, but by cutting out the ocean, we're putting fish back in that have all kinds of characteristics, and probably not necessarily all the ones we need for ocean survival of the next generation. That's the issue.