Farmed
fish, taking advantage of
extremes in tidal flow, leave the confines of their
sea cage, and take to the
open sea and
rivers.
Documented big breaks:
Escapees may carry
disease, such as
ISA, or
parasites, and spread them to
wild populations. They also subject
native populations to
competition and
genetic pollution.
Interesting tidbit: 5 million Atlantic salmon are being farmed off the coast of Maine, near wild rivers. If aquaculture farms prevent 99.99 percent of their salmon from escaping, that leaves 400-500 salmon escapees, which exceeds the total number of wild salmon returning to Maine's seven Downeast Rivers in recent years (under 200 salmon). The actual number escaping each year is unknown, as the State of Maine does not require documentation or reporting of escapees. Escapees have been found in Maine rivers since 1990.