Many fear the carp would unravel food webs supporting a $7 billion Great Lakes fishing industry. Silver carp, the ones that leap from the water with enough force to break boaters’ noses, could give the region’s tourism a black eye.
Knowing how damaging carp can be is important because the fight against them is costing big bucks — and could get lots pricier.
Government agencies have spent more than $150 million on technology to repel the invaders, including an electric barrier in a Chicago-area canal linking Lake Michigan with the carp-infested Illinois River. Five states are suing the federal government to blockade the canal, which would take years and cost billions. Shipping and tour boat groups say that step would be as ruinous to them as Asian carp would be to the fishing industry.
‘‘This kind of research gives an early warning and justification to do everything possible to keep them out,’’ said Marc Gaden, spokesman for the Great Lakes Fishery Commission. ‘‘The more understanding you have of what makes these fish tick and what’s happening in the ecosystem where they've already invaded, the closer you get to maybe discovering ways to get them under control.’’
A U.S.-Canadian team is expected soon to release a Great Lakes risk analysis following an 18-month study. Some experts question whether the lakes have enough warmth and food to support Asian carp. But most say if the hardy fish establish a foothold, they’re likely to find hospitable conditions in bays, nearshore areas and tributary rivers. Warm, shallow Lake Erie, with the most abundant fish numbers, is an especially ripe target.
Scientists are also digging through online databases for clues about how Asian carp have affected lake ecosystems in other countries. Duane Chapman, a U.S. Geological Survey biologist, says silver carp have driven down populations of native species in Europe similar to the Great Lakes’ prized walleye and yellow perch.
Chick offered one possible explanation for why the carp’s impact hasn’t been more dramatic so far: There may be still enough food — for now — to ward off starvation in the Illinois and Mississippi rivers, which are richer with algae and zooplankton than most of the Great Lakes. So the expected die-off of other fish could take years to develop, until a tipping point is reached.
Calculating damage from Asian carp is slow and often frustrating work, thanks in part to the ever-changing nature of rivers. Fluctuating water levels, nutrient runoff and temperatures also affect fish numbers. But researchers are working to solve the mystery before the fish proliferate in the Great Lakes, determined to beat the clock and prevent the feared disaster damage.
‘‘No one knows for sure what would happen,’’ Garvey said. ‘‘But we don’t want to get to that point. We’re looking at some really scary scenarios.’’