Lake Erie anglers may have less of a clue than usual what lurks below the surface these days, because even the experts aren't sure what's happening to the fish out there.
Fish stocks in the lake are changing, and even the way fish populations are measured is hampered by the changing environment, experts said last week at meetings of the Great Lakes Fishery Commission.
Clearer water, the result of a boom in zebra mussels, may mean fish find it easier to dodge the scientists' sampling nets -- a factor researchers said could be throwing off species measurements at a time when fishery managers want most to know what changes are taking place.
"It's changing rapidly," said Dieter Busch, head of the U.S. Fish and Wildlife Service Great Lakes office in Amherst. "We don't know if it's a recovery, but it's going in a different direction," he added.
The stakes in fisheries management are huge. Sport fishing has an estimated impact of more than $11 billion a year in the Great Lakes, and the commercial fishery is valued at about $500 million.
The change is being powered by shifts at the base of the food chain -- elements such as the decline, in recent years, of such "forage fish" as alewives, preyed upon by larger game and food fish.
Zebra mussels, a foreign invader in the Great Lakes, also are altering the chain by filtering vast amounts of water in search of nutrients -- at a rate that now filters the entire water content of Lake Erie in just a few days.
Lake Erie research reviews at the Buffalo Hyatt Regency conference Wednesday echoed Tuesday's reports on a changing Lake Ontario ecosystem.
In reports to the commission, Lake Erie Unit management officials noted that anglers spent about 13 percent more hours on the open lake last year than they did in 1993.
Estimated catches of the most popular sport fish, walleye, were up 48 percent to 59,345 fish.
An experimental early bass season resulted only in a catch of about 1,000 fish, compared to 22,840 during the rest of the bass season.
Officials reported that 3.3 million walleye fry were stocked in Cattaraugus Creek and 800,000 in Big Sister Creek, and that radio transmitters were attached to six adult walleye shifted from Van Buren Bay to the Buffalo River system in a test of trap-and-transfer potentials.
Two commercial fishermen on the U.S. side of Lake Erie harvested 3,006 pounds of yellow perch last year, down slightly from 1993, and the first small harvest of lake whitefish in recent years was logged.