(WBNG Binghamton) Summertime in the Twin Tiers means anglers are out on riverbanks hoping to land the big catch.
Lifetime angler Mark Moll travels all the way from his home in Pennsburg, Pa., to Montrose if he wants to catch bass.
He says the small mouth bass are mostly gone around his hometown.
"I'm not so sure (why), there's just not near as many as there were," Moll said. "I mean we got good large mouth (bass), but the small mouth are really deplenishing bad."
Scientists begnan noticing the decline in the species about 10 years ago.
"In 2005, that's when we really started to notice the decline in the adult bass, and then the underlings followed after that," said Pennsylvania Department of Environmental Protection Community Relations Coordiator Colleen Connolly. "How big is it, we don't know yet."
Scientists with the U.S. Geological Survey are among those studying the problem, along with the DEP.
Patrick Phillips will be taking samples from waterways in southern Pennsylvania, Maryland and West Virginia all summer.
"There's really a variety of physical, chemical and biological reasons for this occurring." said Phillips, a hydrologist with the U.S. Geological Survey. "And trying to teaseout the particular important ones is very difficult because we don't have a nice, controlled laboratory."
Even more fishy, scientists are finding lesions on .the bass and something called inter-sexing.
"Inter-sexiyng is when the female bass takes on the qualities of a male bass and a male bass takes on the qualities of a female bass," said Vicki Blazer, of the U.S. Geological Survey . "And when there's inter-sexing going on, it raises questions as to how well the fish, the bass themselves, can reproduce."
The culprit could be estrogenic compounds that get into waterways.
Animals naturally excrete estrogen, and there are synthetics used in birth control and hormone replacement therapy.
"It's certainly made me aware of all the chemicals we use as pharmaceuticals and chemicals that are in personal care products," Blazer said. "It's not just industry or agriculture, it's our lifestyle and how things have changed and what we are contributing."
The compounds can get into the water through sources like wastewater treatment plants, storm water run off and even farms.
"Ag of course, can be a big contributor," Blazer said. "As you have confined animal feeding operations that have more and more animals, they are naturally excreting hormones."
But Blazer said there may be no single factor or fix.
She and Phillips hope their study can be the hook that brings the bass population back.
"Our study is really trying to give people the scientific information where they can make the management decisions to help protect fish species and fish health," Phillips said. "Better wastewater management, better management of our unused pharmaceuticals, better management of land and other resources."
The New York Department of Conservation reminds people to not flush pharmaceuticals down the drain or toilet.
While there is no evidence the decline is happening in New York, Phillips says if it's happening regionally, it could happen in the Empire State.
"I think we need to keep an eye on what's going on in New York waterways."
Phillips said it will be a few more years until the study is published due to the complex nature of the situation.