I remember talking to an alaska commercial netter. He claimed that a big salmon run up there could spell doom for area steelhead, as they would take quite a few in the nets.
With so many expanded fisheries, it does not take long for a few fish here and there to cause some real trouble. One year I was talking to a tribal friend who was working on a boat that was taking whiting off the coast. I asked about by catch and he stated it was quite low. They were taking a 3 or 4 chinook a night, out of several metric tons of fish. The problem I saw, was that they were one of 3 or 4 four boats that were going to fish for over a month. (The Makah's alone were taking up to 25000 metric tons a year). That would mean their by catch, though small, could be up to 3 - 4 hundred fish. The entire sports fishery for area four was 350 fish.
Imagine how how many steelhead could be taking in herring fisheries, shrimp, all the draggers, purse seiners and others mining the ocean. Just a few per season per boat would probably doom many of our seasons. As one of them and they would say, it was tiny, less than 1/1000th of a percent of their catch. Keep pounding away and in the end, nothing is left. *** just for an added note, it looks like up to a high of 450,000 metric tons of whiting a year have been taken lately. Imagine if they took just one by-catch fish per ton.