Back to reality here folks.

The technology to clone fish does not presently exist. Assuming the cost were similar to cloning mammals (cats dogs, sheep, people), something in the range of $200k to $1000K per animal is the expected price tag.

For a low tech solution to the problem, to achieve more genetic diversity in hatchery fish, why not select for it directly. In a sense hatchery steelhead and salmon are just domesticated animals. Why not do what animal breeders have been doing for thousands of years and select for desirable traits. Why not only spawn those hatchery fish that have desirable traits? ie stronger, bigger or more aggressive fish?

Just my $0.02