Scientists Probe Whether Zebra, Quagga Mussels Behind Lake Huron Fishery Collapse

[hatrack]

Although zebra mussels have been affecting the ecology of the Great Lakes since they were first found in 1988, researchers are continuously surprised at how much damage they've caused. Now, biologists are wondering if zebra mussels and the more recently arrived quagga mussels are to blame for a collapse of the fishery in one of North America's largest lakes. Lester Graham reports the researchers are also wondering if this collapse is a preview of what will happen to all of the Great Lakes:

It's off-season for charter boat fishing and Captain Wayne Banicky asked if we could meet at a local watering hole called the Boat Bar. Captain Banicky takes people out fishing on Lake Huron. Well, he used to. The past few years he's been charter boat fishing in Lake Michigan. He says fish started to become more scarce on Lake Huron, and he was forced to make the move. "Economics, pure and simple. Dollars and cents. Once you start seeing a decline and being on the water every day and you see those declines in your numbers, it's just a matter of time before financially you can't afford to stay there. Those dock fees aren't given up free. That's an expensive tab to pay every year."

Fishing for most species in Lake Huron is not good. But the story is not just a matter of not stocking enough fish or just a bad year, it's a matter of a collapse of the bottom of the food chain. It's not just the fish sport fishers like to catch that are down, it's their prey: the smaller fish those big game fish eat. Prey fish stocks have collapsed, and supplies of the food those small prey fish eat, the plankton, have also collapsed. Jim Johnson is with the Michigan Department of Natural Resources Alpena Fisheries Research Station: "There was a huge decline in the amount of nutrients available to zooplankton and phytoplankton in the middle of Lake Huron. These are the basic nutrient bits that fish eat. And it appears now to most of us in the scientific community that a large portion of the nutrients that used enter Lake Huron are now being trapped by zebra and quagga mussels and not finding their way to alewives and other prey fish."

Scientists from different government agencies and universities in the U.S. and Canada had been noticing changes, but things have gone seriously wrong very quickly in Lake Huron, and it might go wrong other places. Tom Nalepa is with the National Oceanic and Atmospheric Administration's Great Lakes Environmental Research Lab. He says tiny aquatic food sources for fish, such as a shrimp-like organism called diporeia, are declining dramatically in other Great Lakes. "All the players are in place for it to happen in these other lakes too, you know, the loss of diporeia, the expansion of quagga mussels. And maybe Lake Huron is the first to show a collapse in the prey fish. What does it mean? Well basically, you know, there's not going to be many fish out there for the sport fisherman to catch anymore."

EDIT

http://www.glrc.org/transcript.php3?story_id=3213

[Porcupine]

1. So what eats zebra mussels?

You can't put the genie back in the bottle but maybe you can learn to live with it. Something out there eats zebra mussels in preference to everything else. Find it.

[phantom power]

2. And now we're doing the same thing to the oceans.

Crashing the food chain from the bottom up. Not a problem of course, since our land-based agriculture is in great...

oh, never mind.