This high rate of straying is another good reason why the use of hatcheries should be limited and potentially phased out. Hatchery fish have been shown to stray a good deal more than wild fish (a quick google search for "hatchery salmon strays" will give you hours of reading) and this leads to increased interaction between wild genetics with the hatchery fish. So even in a system with no hatchery program there can be similar problems with competition, dilution of gene pool and increased fishing pressure seen on systems with hatcheries. Hatchery fish have definitely been shown to be less fit and not nearly as good at reproducing as their wild, native counterparts. These wild fish have had selection pressures specific to the river system where they live to mold the gene pool to be most successful, while the hatchery fish have had very little selection pressure at all, other than which ones can swim in the best circle around a tank (obviously this is only pre-release). This looser selection process probably plays a role in their tendency to stray, as there isn't 10,000 years of evolution specifying those fish to a particular system. so, go bonk a hatchery fish!!

Matt Korb