Overfishing of salmon has caused populations of wild salmon to decline. To combat this decline, salmon are raised in hatcheries, and then released to the wild. However, researchers have found that hatchery-raised salmon have reduced reproductive success in the wild, compared to wild salmon. They have also identified many genetic differences between hatchery-raised and wild salmon.

Which statement describes the most likely reason for the differences between hatchery-raised and wild salmon?

A.

Hatchery-raised salmon develop into stronger swimmers than those raised in the wild.

B.

The pressures of a hatchery environment and of the wild environment select for different traits.

C.

Hatchery-raised salmon have evolved to have completely different genomes from those of wild salmon.

D.

The pressures of a hatchery environment promote convergent evolution between hatchery-raised and wild salmon.

The hatchery bred salmons do have different traits as compared to the wild salmons because of the environmental effects it does have on their maturity.

Option B.

Explanation:

The wild varieties of salmons do live in natural streams and rivers and do have to collect their own food themselves. They face the struggle for their existence as well as they have to compete with each other for getting food. So their adaptation is very high and specialized.

Whereas the hatchery bred salmons get their food from what is supplied to them. They get perfect conditions for living artificially. They also doesn't face wild traits of diseases which do often attack the wild varieties, so lacks the immunities against them. Thus these differences lead to the different traits between them. Thus they cannot survive together and it will lead to a divergent evolution, or the survival of the fittest and natural selection will eliminate the hatchery bred varieties because if their incapabilities.