The initial selection of farmed Atlantic salmon took place from fish drawn from forty different river systems.
(A)
But whatever the manifestation of difference that occurred in different species of salmon, the first salmon farmers realized that crossing and recrossing the specific families from the original forty rivers would result in salmon that grew faster.
(B)
And because salmon, unlike cattle and sheep, can produce many thousands of offspring in the course of their lives, once favorable individuals were found, just a few strong males and females could form the basis of a whole new race of highly productive fish. A domestic population could be created quickly that would be quite different from the initial wild ancestors.
(C)
Every salmon river has its own unique set of challenges to which fish must adapt. Some rivers are very long, like the Yukon, and require animals that can build up massive fat reserves in order to survive the extended journey. Others are very far north, with only a short season of warmer temperatures, and require a fish that can maximize growth, particularly during its younger phase.
* manifestation: 표현 ** offspring: 자손
