zebramussels

Grant Township, Cheboygan County, Michigan
www.granttwp.com

Zebra Mussels Are Here to Stay in Black Lake

Bad News For Fish and Fisherman:

What We Know:

A single zebra filters algae and plankton (food sources
for fish from egg to 4 mo. old) from between one quart
and one gallon of water per day.
The number of zebra mussels in the lake will grow and
shrink to maintain a constant, very low level of food for
fry.
Availability of food is only one of the actors affecting
survival of young fish, but even years with favorable
spring conditions will produce fewer surviving fish.
It has been 9 years since we have had a strong year of
naturally reproduced walleye (zebra mussels were first
detected in 2003)
Stocking alone will not return fish populations to "pre-
zebra" levels due to size of lake and availability of
fingerlings.

What We Can Do:

Continue to stock fingerlings (fish beyond plankton
feeding age)
Gather data regarding food for fingerlings and mature
fish (e.g. are populations of shiners and bugs stable or
decreasing?)
Increase harvesting restrictions on Black Lake.
Improve upstream spawning grounds.
Is Black Lake more impacted as a fishery than other
lakes because much of the lake is shallow? (where
zebra mussels live)

It Could Get Worse!

What We Know:

We don't have the VHSv virus in Black Lake.
Introduction of this virus (minnow buckets, stocking
infected fish) could collapse the walleye population.
We don't have Quagga mussels in Black Lake. They
feed year round and at greater depths than zebra
mussels. Again, this could be devastating to the
walleye population.
We may see continued growth of weeds and bottom
muck as nutrients are transferred from free floating to
waste matter on the bottom and the water clarity allows
more sunlight to greater depths.

What We Can Do:

Monitor changes in weed growth and bottom muck.
Improve controls over introduction of additional
invasive species and diseases into the lake.

What We Know:

The European community has been unable to find a
control after two centuries of infestation.
The only chemicals that are available to eradicate them
are carcinogenic and eliminate all marine life along with
the zebra mussels.
Very high reproductive rate: A female releases 30 million
eggs into the water at a time.
Even if zebra mussels were eliminated from Black Lake,
they would return through movement of boats, bait
buckets and birds.

What We Can Do:

Monitor what others are doing about management
(sterilization disease, predator research)
Educate BLA members about controlling migration of
new invasive species (e.g. Quagga Mussels)

Reasons To Be Thankful:

What We Know:

Bass, perch, and sturgeon, have, so far, fared better
than walleye (little is known of affects on or counts of
muskellunge)

Survival rates of stocked fingerlings have been better
than expected (or feared), though they may feed on
naturally reproduced fry.
The filtering function of the zebra mussels makes for a
very clear, pretty lake that couldn't be more pleasant for
swimming.
The affect of increased nutrients in storm water runoff
(from farms, lawns, roads) are offset by zebra mussels,
although these nutrients still accumulate on the lake
bottom and promote weed growth.
Fish survival may improve as numbers by class and the
affect of predation balances out. Today, there are more
mature fish in relation to young.

What We Can Do:

Control sources of new nutrients from fertilizers, pets,
soaps, detergents, septic systems and storm water.
Monitor changes in weed growth and bottom muck.
Continue to monitor fish counts by class every year. Are
stocked fish surviving only because of past weak year
classes?