Fish Help in Restoration of Mussel Population
25 July 2013
By John McCoy
CHARLESTON, W.Va. -- To help restore mussel populations wiped out
by two major chemical spills, West Virginia fisheries biologists
have sought assistance from a few finny friends.
"Most mussel species require a fish host to reproduce
successfully," said Janet Clayton, the Division of Natural
Resources biologist in charge of the agency's mussel-restoration
"So, to make sure the mussels we want to restore get the fish
hosts they need, we take larvae from [recently spawned] mussels
and we put them in the gills of the fish."
The process sounds simple, but it's anything but.
Clayton and her colleagues first must spend untold hours
snorkeling and scuba diving, probing creek and river bottoms to
find mussels that have bred. Once they've captured their brood
stock, they gently pry the mussels' shells open and flush the
larvae out with water from a hypodermic syringe.
They then inoculate the fish hosts by allowing the fish to swim
through a tank teeming with salt grain-sized larvae, or by using a
syringe to inject larvae-rich water into the fishes' gills. When
the larvae mature, they drop off the fish and sink to the bottom
of the holding tank. Biologists collect the mature larvae and
distribute them along the river bottom.
"While the larvae are living in the gills of the fish, they're
essentially parasites," Clayton said. "But they don't harm the
fish at all."
The propagation process is expensive and labor-intense, but
Clayton said it's necessary if natural resources officials ever
hope to correct the damage wrought by a 1999 chemical spill on the
Ohio River near Parkersburg and a 2009 spill on Dunkard Creek
north of Morgantown.
"We could try to restore damaged populations by relocating them
from places where they're plentiful to places where they were
wiped out, but that's just robbing Peter to pay Paul," she said.
"Ideally, we'd prefer to restore populations through propagation."
It will take quite a bit of propagation to restore the mussel beds
wiped out by the 1999 Ohio River spill. According to the U.S. Fish
and Wildlife Service, chemicals from the Eramet Marietta metals
plant in Marietta, Ohio, killed 990,000 mussels along 30 miles of
Resource agencies eventually reached a settlement with the company
and its affiliates that earmarked $2.04 million for mussel
restoration efforts. Biologists began the restoration work in
The Dunkard Creek kill, while not as far-reaching as the Ohio
spill, was no less devastating. It killed everything -- fish,
mussels, crustaceans and even insects.
Inspectors officially placed the blame on a bloom of golden algae,
most likely created by salt-laden water escaping from a large
underground coal mine.
"There was no [mussel] brood stock left on Dunkard Creek," Clayton
said. "Left to its own, it would never have recovered."
Clayton and her colleagues devised a way to restore the creek's
mussels and fish populations at the same time.
"Rather than spend a lot of time in [mussel] propagation, we
collect our brood stock, extract the larvae, inoculate fish with
them, and then stock the fish into the creek," she said. "We're
also relocating some adults into the creek. We did our first
inoculation and release last year, and we did one again this
Some mussel species can use a variety of fish species as hosts,
while others require specific hosts.
"The species-specific ones definitely complicate the process,"
Clayton explained. "When a host fish is commercially available --
bluegills, for example -- we just raise them in one of the state's
hatcheries or go out and buy what we need.
"For other species, such as creek chubs and stonerollers, we go
out and seine them from creeks. One mussel species, the pink
heelsplitter, requires us to go out and capture freshwater drum.
So even getting the fish hosts involves a lot of work."
Restoration efforts on the Ohio have centered on nine mussel
species: three-ridge, Ohio pigtoe, pimpleback, maple leaf,
washboard, black sandshell, sheepnose, pocketbook and fat mucket.
"So far we've had limited success with five of those species,"
Four species -- the creeper, giant floater, fluted shell and
fatmucket -- are being reintroduced to Dunkard Creek.
Collecting larvae from breeding mussels can involve some pretty
"There are two basic types of mussels -- long-term brooders and
short-term brooders," Clayton said..
"Long-term brooders hold their larvae for several months, so
they're pretty easy to collect from. Short-term brooders aren't as
"We know the general time frame when their larvae become mature,
so we collect some adults, put them in containers and wait for
them to release their larvae. When we see lots of mature larvae,
we go out and collect more adults and continue the propagation
process from there."
Sometimes, though, knowing the right time isn't enough.
"Last year, [streams'] water warmed so quickly that the mussels
spawned early and we just about missed our first species," Clayton
said. "This year was the opposite. We got very few larvae off our
first species, and the water since then has been too high to
collect more brood stock."
So why go to all this trouble to restore creatures many people are
unaware even exist? In a word, ecology -- the way creatures
interact with their environment. Clayton said mussels are
important to streams' ecosystems because they filter impurities
from the water.
"A bed containing 200,000 mussels can filter a million gallons of
water a day," she said. Imagine how much money we could save in
water-treatment costs if our native mussel communities were
Reach John McCoy at johnmc...@wvgazette.com or 304-348-1231.