Shenango River Lake assessment brings good, bad fish news
The story of the fishery at Shenango River Lake is a good one, especially as relates to bass.
But you might wanna get 'em while you can.
Trouble's brewing at the U.S. Army Corps impoundment.
Biologists from the Pennsylvania Fish and Boat Commission surveyed the Mercer County lake earlier this summer, assessing its bass population. There was good news, different news and bad news.
The good news relates to bass. Things look pretty good where they're concerned.
Crews electroshocked three areas. The total number of bass collected was 57.8 per hour, which is slightly above the long-term average, said Freeman Johns, a biologist in the commission's area 1 office in Linesville.
“For a large reservoir, that's a good number,” said Tim Wilson, another biologist there.
The catch rates per hour of fish exceeding 12 and 15 inches is also good, he said.
The fish seen included largemouths and an almost equal number of smallmouths. But the largemouths are typically larger.
Biologists handled one 20-inch largemouth, along with lots of fish between 13 and 18.
The smallmouth population, by comparison, is dominated by fish that go 6 to 11 inches.
“We saw a few bigger smallmouths,” Wilson said, pointing to one that stretched nearly 18 inches. “But most of the trophy bass in Shenango are largemouths.”
As for the different news — neither good nor bad, necessarily — it's about catfish.
Shenango long has had a nice population of channel catfish. That remains true, Wilson said.
It also now is home to a growing population of flatheads.
“We got a few when we surveyed there in 2014. We got quite a few of them this year,” Wilson said. “And we saw some big ones. Giant, whopper flatheads.”
They're an apex predator, Johns said. But whether their presence will impact the channel cats or the lake's panfish remains to be seen.
What is perhaps likely — and here's where the bad news comes in — is that another fish that turned up in this year's survey will spell problems.
Alewives, sometimes called alewife, are a kind of herring. Originally a species that lived in salt water and migrated into tributaries along the East Coast to spawn, they since have spread into any number of freshwater lake and river systems.
Shenango is the latest water to get them.
“We've had them in Pymatuning Lake for quite a while. It seems like they finally made their way down the (Shenango) river, and now there appears to be an established population at Shenango Lake,” Wilson said.
“I have no idea what that's going to mean.”
There's cause for concern, though.
For starters, once alewives get into a waterway, it's impossible to get rid of them, Wilson said.
They can upset ecosystems, too. They often outcompete native panfish, leading to stunted populations of crappies and bluegills. That's happened at Pymatuning and Lake Wilhelm, Wilson said, and could prove troubling for Shenango's popular crappie fishery.
Predatory fish can be impacted, too, though in a different way.
In the early 1990s at Pymatuning, for example, the walleyes caught averaged just 14 to 16 inches, Wilson said. But anglers got lots of them.
These days, there are still plenty of walleyes in the lake — the commission's trap-net catch this spring was its second highest ever — and they're bigger, averaging 19 inches. But they're also much harder to catch.
The lake's gigantic population of alewives is the reason.
“The walleye population is actually showing signs of under-exploitation,” Wilson said. “But when they're able to eat to their hearts content, they're just not interested in a nightcrawler or a minnow.”
For a while, Lake Wilhelm's bass were hard to catch for the same reason.
Whether the bass fishing at Shenango is likewise headed for an era of plentiful and big but hard-to-catch fish isn't certain.
A lot will depend on whether the alewife population explodes or merely survives at some low level, Wilson said. And there's no telling which scenario might come true.
“There's really no way to predict what might happen,” Wilson said. “We'll just have to wait and see.”