Dr. Cathal Gallagher:

They come back to the same river each year and the same populations go out. Some rivers are still at a reasonable conservation status, although not as many as we would like, while some are really poor. That contributes to the overall population. The big issue is what has happened in the ocean. In the 1970s, for every 100 juveniles that went out into the ocean, 20 adults would come back. Now, for every 100 that go out, you will generally get five back.