In a finding that could change trout-stocking practices in Pennsylvania, the U.S. Geologic Survey has unveiled research that shows stocking of brown trout in brook trout habitats could drastically decrease brook trout numbers.
"There is great potential for brown trout stocking to reduce native brook trout populations," said James McKenna, USGS scientist and lead author of the study, which is published in the *North American Journal of Fisheries Management and is available online at http://www.tandfonline.com/doi/full/10.1080/02755947.2013.830998#.UrDAtHC-pKA>
The findings of the study are especially interesting in Pennsylvania, where brown trout have been stocked for many decades in waters harboring wild brook trout, and where many wild brown trout populations were created long ago by stocking in formerly wild brook trout waters.
The USGS study found, of course, that human-induced degradation of trout habitats – from dams, roads and the construction of shale-gas infrastructure, such as well drilling pads and pipelines – is the biggest threat to wild brook trout.
Because brook trout do better in forested watersheds and brown trout can thrive in more agricultural environs, degraded watersheds and/or the elimination of forests may affect brook trout more than brown trout.
That's a grave concern in the Keystone State where shale gas development is occurring at a torrid pace in the public-land forests of the Northern Tier, where most of the vulnerable wild brook trout populations exist in small streams.
In New York, where the research was conducted, the brook trout has been declining within its native range in recent decades, and there has been concern that the stocking of brown trout has caused these declines.
But in Pennsylvania, with the shale-gas onslaught threatening so many wild-trout streams across the Northern Tier, fisheries managers have way more to worry about right now than if brown trout are outcompeting and interfering with native brookies.