Modest_Man said:
Single biggest hatchery fish issue is the loss of genetic diversity that hedges against natural disasters (and human caused disasters). With the introduction of cookie cutter hatchery strains alternate life history strategies have disappeared. It's going to take more than 15 years (7 generations) for that depressed genetic diversity to make a comeback. Can it come back? Sure. Not going to happen overnight though. It took several million years to produce it, and humans (almost) destroyed it in 130.
If you guys are seriously interested check out books by Jim Lichatowich (Salmon Without Rivers and Salmon, People, and Place: A Biologist's Search for Salmon Recovery) or David Montgomery's King of Fish. (They're all depressing but Montgomery's is more depressing).
I have been thinking on this issue for a while now so here goes:
first, it seems there are methods to mitigate potential harm to wild fish when planting the hatchery smolts, these methods are not free and require planning, but it seems we can get in lots of hatchery smolts by using multiple locations, spreading out the plantings over time also, basically avoid ever overloading the system with too many hatchery fish so as to avoid having them over compete the wild fish for available food.
now to the genetics- if the fish being planted in a system are born from wild fish returning to that system, I need help to understand the problem.
Let me use the Siuslaw program as an example- returning wild winter steelhead adults are trapped each year and only wild fish are used to generate the hatchery smolt that get planted back into the Siuslaw. So the smolt being planted all come from parents that were born wild and were returning to the Siuslaw to spawn.
Now we need to assume that some hatchery fish will get into the spawning festivities but remember that their parents were fish born wild in the system. So genetically, they are wild fish with just one hatchery/fin-clip/planting cycle..
..so the fish spawning in the river each year could be a mixture of mostly wild born fish and a few hatchery born fish
but genetically they are all Siuslaw steelhead, essentially no genetic difference between 'high fin' and 'clipped' because the hatchery born fish are the direct offspring of wild born Siuslaw fish? I mean, the term 'cookie cutter hatchery strain' just doesn't seem to apply if the clipped fish are first born from wild fish.
did I miss something in the science or is 'cookie cutter' just code for 'cheap'?
cheers, roger