Aside from eating up millions in salmon recovery dollars, hatcheries and hatchery fish pose two challenges to wild fish.
"The science is clear and unambiguous -- as they are currently operated, hatcheries and hatchery fish cannot protect wild stocks".
Thus, some breeder facilities that supply eggs to hatcheries, and hatcheries that ultimately produce "organic" chicks, do not have to meet any organic standards and can therefore use antibiotics among breeder stocks and inject antibiotics into eggs.
In experiment II, the effect of physical environment and nutritional competition on the expression of survival and growth of farmed, hybrid and wild salmon was investigated under standard hatchery conditions, hatchery conditions with restricted access to feed, and in a predator-free semi-natural environment.
In addition to relatively lower survival and reproductive success of hatchery fish, hatchery release numbers may have been sufficiently low to avoid genetic homogenization via increased gene flow between hatchery and wild fish (Slatkin 1985; Adkison 1995; Eldridge and Naish 2007).
Half of the broodstock crosses were wild × wild, and the other half were hatchery × hatchery, resulting in an average of 50% wild contribution to broodstock.
The parental cross groups were pooled by cross type (wild mother x wild father, wild mother x hatchery father, hatchery mother x wild father, hatchery mother x hatchery father) for analysis of body-size differences within each rearing environment.
Differences between hatchery and wild populations are not always found; Dahl et al. [74] found no significant differences between wild and hatchery brown trout (Salmo trutta); however, hatchery conditions and length of time the broodstock has been maintained in hatcheries may have an effect on these variables.
Reviews of the genetic impacts of hatcheries on wild populations (e.g., Hindar et al. 1991; Waples 1991; Busack and Currens 1995; Ryman et al. 1995; Naish et al. 2008) have identified three important processes: (i) effects of hatcheries on the fitness of hatchery fish, and (ii) direct and (iii) indirect effects of interactions between wild and hatchery populations.
Counterintuitively, the relationship between the number of hatchery-produced adults on the spawning grounds and hatchery smolt proportions was consistently negative, suggesting that more hatchery-produced adults on the spawning grounds produced fewer hatchery descent smolts.
