Invasives destroying Great Lakes food
By Lester Graham
The Environment Report
Published November 13, 2006
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
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
And sport fishing is multi-billion dollar industry in
the Great Lakes. Back at the Boat Bar, charter fishing
boat captain Wayne Banicky says fishing is still good
in Lake Michigan, but he worries when he thinks about
what happened in Lake Huron.
"I think that the fishery as a whole in the Great
Lakes is in serious jeopardy right now. Something's got
to be done."
But the question is what? What can be done when invasive
species are changing an entire ecosystem to the point
the fishery collapses?
"I don't know to be honest with you. I don't think
any one of us knows. It's scary, that much I will admit
to you. It is scary right now."
And guys like Captain Banicky aren't the only ones worried.
Jim Johnson at Alpena Fisheries Research Station says
you can't undo the damage that's already done. It's just
a matter of waiting to see how nature responds to the
invasive zebra and quagga mussels and other invaders.
Johnson says the key is to prevent more invasive species
from being introduced to the lakes.
"The best we can do right now, I think the single
most effective thing we as managers can do, is to make
it understood by the decision makers just how disruptive
the invasive species are and try to put a stop to those."
The source of many of these invasive species is the ballast
tanks of foreign ships entering the Great Lakes. Some
regulations have reduced the chance that more invasive
species will hitchhike to the Great Lakes, but more are
still getting in. In the meantime, agencies such as the
US Environmental Protection Agency and the US Coast Guard
say Congress hasn't given them the authority to regulate
foreign ships strictly enough to stop new invasive species
So, fishery managers can only watch the other Great Lakes
for more signs of a collapse of the fisheries as they've
only been able to stand by and watch happen in Lake Huron.
For the Environment Report, this is Lester Graham.