brook trout

A wild brook trout.

The debate among anglers about whether stocking hatchery-raised brook trout in Pennsylvania streams is harmful to wild brookies already there is likely to continue after a new Penn State study.

On one hand, the research showed that hatchery brook trout stocked in streams in the Loyalsock Creek watershed in Lycoming and Sullivan counties rarely passed their genes to the wild trout already there.

That’s good news since hatchery fish are generally less resilient, fit and less likely to adapt to changing habitat and climate.

It also might mean the Pennsylvania Fish and Boat Commission can stock brook trout — increasing angler opportunities — without worrying about tampering with truly wild native brook trout.

Even with frequent stocking in some 30 different sites in the Loyalsock watershed, 93 percent of wild-caught brook trout showed no signs of the genes of hatchery fish swimming in their midst, according to the study by the College of Agricultural Sciences.

The likely reason: Hatchery fish die within a few months of stocking because of low fitness levels, notes Shannon White, lead researcher and Penn State doctoral degree student in ecology.

Most seem to die in warmer water and few appear to be around for the October-November spawning season.

But wait.

The researchers also warned that the study should not be used for a no-holds-barred endorsement of stocking brook trout anywhere wild brookies exist.

White urges state agencies and private groups to make stocking decisions on a watershed basis, rather than a stream basis.

“In our research, we saw evidence that hatchery trout — and their genes — traveled farther than we would have expected, into small tributaries far from stocking points,” White said.

The research was supported by the R.K. Mellon Freshwater Research Initiative, the National Science Foundation and the U.S. Fish & Wildlife Service.