Pittsburg (WKOW) -- Researchers in Pittsburgh have spent a lot of time on a fishing expedition.
The information they've collected is food for thought.
It's a hot, hazy day on the Allegheny River near Pittsburgh.
And this boat load of researchers is fishing for clues about the health of our rivers.
Dr. Conrad Volz said, "fish essentially are the canary in the coalmine for water quality."
Doctor Volz's team takes samples from the bottom of the river bed, plus analyzes fish caught in these waters.
They've found a virtual stew of contaminants left behind by years of pollution from coal-burning plants.
Volz added, "the problem is, not only one of CO2, which you hear about all the time and greenhouse gases, but they give off heavy metals, such as mercury. They give off arsenic which is a metalloid and they give off a toxic element called selenium."
Between those pollutants and the estrogens found in the rivers from sewage, it makes the fish so sick, research suggests humans should avoid eating the fatty layers.
But Volz said that was a problem. He said, "unfortunately, these are the fish that we like to eat."
Doctor Volz doesn't think we need to stop eating fish entirely, but wants us to ask the right questions about the fish we pick.
He said, "I ask at the fish market all the time, where the fish comes from that I'm buying."
You can also trim away the trouble spots.
Volz added, "you can rid yourselves of those contaminants in the fish that are fat-loving by removing this portion of the fish that's essentially the fat."
Doctor Volz would like to see the government force fish sellers to label it, to let us know where it comes from.
Until then, ask, and make your choices educated ones.
Doctor Volz says salt water contains many contaminants.
So he suggests eating smaller fish from the ocean, including snapper, pacific cod, and salmon.