An eight-year study of the region’s three rivers, the most comprehensive ever, found the Allegheny River was home to the highest number of fish species while the Ohio and Monongahela had the most so-called “game” fish.
The Allegheny was the cleanest of the three rivers, hosting the greatest number of pollution intolerant fish species, indicating a higher environmental quality, which bodes well for the river remaining a major drinking water source for more than 300,000 customers in the region.
Although a patchwork of fish studies has been done over the years, there wasn’t any one study to serve as a baseline for the region’s three rivers, specifically the tailwaters created by 17 locks and dams.
The Pennsylvania Fish and Boat Commission conducted the survey from 2008 through 2016 at night, electroshocking fish to gather information on game and other species, comparing their presence in different tailwaters.
Game fish are those most sought after by anglers.
Commission workers collected 16,361 individual fish representing 69 species and four hybrids, with the highest number, 61 species, in the Allegheny, and the lowest, 41, from the Ohio.
“The real guts of the study will come into play 10 years from now when we have follow-up data,” said Rick Lorson, area fisheries manager in Somerset for the commission.
In the event of pollution sullying the rivers, the commission will have baseline population information to assess any losses.
With the survey, the commission will be able to monitor efforts “toward abatement and control of industrial pollution, sewage, industrial discharges, mine drainage, frack water and nonpoint source pollution,” Lorson said.
The survey will be used by the state Department of Environmental Protection and the federal Environmental Protection Agency.
DEP described the survey as “consistent with DEP’s own data showing improving health of the Allegheny, Monongahela, and Ohio rivers,’ said Lauren Fraley, DEP spokeswoman.
The Allegheny River has more diversity and richness in its fish populations because of its history of lower pollution levels than the other two rivers.
But, while the Monongahela and Ohio rivers were heavily polluted in the past, their fish numbers have been rising steadily and enough for game fish to prosper, according to the survey.
The “big three” game fish — smallmouth bass, walleye and sauger — of all sizes were most abundant in the Ohio River.
While Lorson said he can’t draw a specific conclusion from that, he said, generally, “bigger water provides more area and is appealing to the game fish.”
The survey looked at total catch and size: The larger walleye were found in the Allegheny.
In the category of pollution-intolerant fish, researchers found anywhere from 11 to 16 species in the nine samples collected from the Allegheny River.
Samples from the Monongahela included six to 10 pollution-intolerant species and, in the Ohio, researchers found six to nine species in samples, according to Lorson.
Species diversity increased as researchers sampled farther down each river.
A native brook trout stream in Westmoreland County that serves as tributary of the Allegheny River might have only two species of fish.
“That’s what you see as you come out of the mountains, approaching the Allegheny River. Going downstream, you pick up more species,” Lorson said.
For example, the Allegheny’s Kittanning pool was found to have 38 species of fish but the Harmar pool, farther down river, was found to be home to 41 species — the highest number found in the survey’s 17 tailwaters.
Fish and Boat Commission crews will return to the rivers this spring to start the next cycle of surveys.