Listen closely around shallow backwaters of the Ohio, Allegheny and Monongahela rivers. Those jerky "grunts," often heard from June through August, aren't necessarily coming from frogs.
It's spawning time in Pittsburgh for freshwater drum. In summer, males rise to the surface or shoreline and force air through a special set of muscles that vibrate against the swim bladder. Scientists don't know the meaning of all that croaking or drumming, but because it occurs only among mature males, they suspect it may be drum-speak for "Your place or mine?"
Few anglers target the fish, also called croakers, silver bass or sheeps-head, perhaps because they live low in the water column and fight deep with no surface acrobatics. Their flesh is readily edible but not touted by connoisseurs as a walleye-quality plate fish.
But freshwater drum may be the Three Rivers' most under-appreciated gamefish.
"I really don't know what the prejudice is against them," said Pittsburgh fishing instructor Karen Gainey. "You get a 3 or 4 pounder on and they fight really hard, like a big catfish. I don't know why somebody would not want to catch one."
Among the most wide-ranging species in North and Central America -- common from Hudson Bay to Guatemala, from the Appalachians to Texas -- the drum is native to the Ohio River system and Lake Erie.
In southwestern Pennsylvania waters, drum are naturally reproducing and plentiful, not particularly hard to catch and grow to substantial size. In 2012, the state Fish and Boat Commission gave Angler Awards for drum ranging from 8 pounds, 26 1/2 inches, to 14 pounds, 2 ounces and 34 inches. The state record, set in 1994 on the Monongahela River in Washington County, is a whopping 19 pounds, 14 ounces.
Down South, where drum can reach some 50 pounds, anglers target them using live crawfish, deep-diving crank baits -- even fly rods with sinking line and Clouser minnows. The U.S. commercial harvest of drum exceeds 1 million pounds per year.
Gray or silver in cloudy waters, bronze or brown in clear waters, the freshwater drum has a sharply arched back and two dorsal fins -- the spiny top fin is narrowly attached to a longer soft-rayed fin. The lateral line visibly extends through the tail. Behind a white belly, the large anal fin has two spines.
Deep in the throat, big molar-like teeth are used to crush snails, clams, mussels and crayfish, although the drum's primary spring diet consists of insect larvae, and summer through fall it eats mostly gizzard shad and emerald shiners.
The sole freshwater member of a large family of saltwater fishes, the drum is the only North American freshwater fish with eggs so buoyant they float. When waters reach 65 degrees, females broadcast 34,000 to 66,500 eggs into the water column, and males randomly fertilize. The eggs float off and hatch in two to four days. No parental care is given to the young.
With no need to stock drum and virtually no risk of population depletion, Fish and Boat provides minimal oversight of the fishery. The drum is included in Three Rivers gamefish counts and lumped into a broad regulatory category with panfish, perch, catfish, carp and suckers with no closed season, no size restriction and a 50-fish combined species creel limit. Despite its hefty size and high incidental catch rate, the drum isn't even mentioned in the published regs -- it's covered by the line "and other gamefish not otherwise listed."
Longtime host of the former Venture Outdoors Downtown Tri-Anglers fishing program, which was cancelled this year, Gainey said about 20 percent of the fish caught off the North Shore during the Wednesday afternoon outings were drum. Often, anglers didn't recognize the fish.
Gainey teaches fishing strategies and tactics at Community College of Allegheny County, hosts "Karen's Fishing Corner" on Pittsburgh public access PCTV and is instructor at a new monthly fishing series at Point State Park. She said drum go for live minnows, leaches, crawler-tipped jigs or soft plastics --a sliding sinker or floating jig head keeps the bait near but off the bottom.
"I've caught 4 to 5 pounders at Lake Erie on just about anything fished deep," she said. "You can catch drum just about anyplace on the rivers. Anywhere you're picking up walleye or sauger, expect drum to be there. And when you have a fish on that's fighting like a big catfish, it might be a drum."