To Breach or Not

First, a few words about escaped salmon from fish farms:

The reason the issue of escaped salmon deserves our attention is that there are legitimate environmental concerns that result from a farmed fish escaping. In British Columbia, both Atlantic and Pacific salmon are being raised in farms and each of these two species poses unique risks once they do escape. For Atlantic, there's hybridization, which is basically Atlantic and salmon crossbreeding -- Atlantic and Pacific salmon crossbreeding. The other is predation and competition. This involves the Atlantic feeding on wild Pacific salmon, as well as other food supplies, and then the taking of space and the wild habitat in general.

Another major concern is spawning site disruption by Atlantic salmon. The stems from the fact that Atlantic salmon spawn later than Pacific salmon so there's a risk that they enter the same streams that the Pacifics have already spawned in and then they disrupt the eggs that the Pacific salmon have already placed. And also, Atlantic salmon mature faster than Pacific salmon, and so they have a competitive, or they give to the Pacific salmon a competitive disadvantage due to their smaller size. Another concern is colonisation of Atlantics in BC, which would have severe impacts on the wild stocks -- mainly because they would be using the same streams that wild Pacific stocks presently use to spawn. And finally, there is the issue of the spreading of diseases from the farmed salmon to the wild Pacific salmon.

Current Status of Salmon Migration and Survial Rates as measured by the National Marine Fisheries Service