CANADA-ONTARIO AGREEMENT RESPECTING
THE GREAT LAKES BASIN ECOSYSTEM
Since
the 1800s, scientists have identified more than 160 invaders – fish,
crustaceans, aquatic plants and species of plankton – that have successfully
infiltrated and found a permanent home in the Great Lakes. On average,
that is one new species successfully integrating into a delicately-balanced
ecosystem every 11 months. Some are so common, the carp, the alewife,
the lamprey, that many people think they must have always been here. While
some invaders co-exist peacefully with the native inhabitants, about one-in-ten
explodes on the scene like an environmental bomb.
The scientists call them aquatic non-native invasive species (nis). With
no natural predators, parasites or pathogens, aquatic NIS can spread quickly
throughout a water body. Once firmly established, a prolific aquatic NIS
like the zebra mussel can permanently disrupt an ecosystem’s biological
integrity. Aquatic NIS can wrest habitat, food resources and spawning
sites from native species, driving their competitors into retreat or even
extinction.
Although the governments of Canada and the United States, along with
the Government of Ontario and state governments have had some success
in managing the sea lamprey, other aquatic NIS are out of control, and
new invaders continue to reach the Great Lakes Basin every year.
On average, another aquatic non-native invasive species
grabs a niche in the Great Lakes ecosystem every 11 months.
Portrait of a typical aquatic NIS
“The successful aquatic NIS is usually a colonizing species in its
own home environment as well ours,” says Dr. Doug Dodge, a retired
Ministry of Natural Resources biologist specializing in Great Lakes issues.
During his career, Dr. Dodge worked with the International Joint Commission
and the Great Lakes Fishery Commission on the control of aquatic NIS.
Aquatic NIS are very accommodating, very hardy, and very adaptable plants
and animals, says Dr. Dodge. The animals tend to be voracious eaters and
are extremely prolific, quickly grabbing a huge chunk of a lake’s
productivity for themselves and starving out their competitors. The plants
are typically aggressive colonizers that spread quickly, crowding out
the meeker indigenous vegetation.
“It’s one of the great ironies, that invading species weren’t
a major problem when the lakes were heavily polluted,” says Dr. Dodge.
Once we collectively began to improve sewage treatment, clean up industrial
wastewaters and reduce nutrient loadings, the native species took too
long to reoccupy their former range. “Non-native invasives quickly
took advantage of the opening and moved right in,” he says.
Like the proverbial unwanted house guest, aquatic NIS can be nearly impossible
to get rid of once they’ve got a fin firmly lodged under the dinner
table. The best way to control an aquatic NIS is to bar the door tightly.
“There is usually some futile attempt to find a biological predator
to control the invasive,” says Dr. Dodge, “but then, who will
tame the tamer?”
Musseling in to the Great Lakes
Look
up “non-native invasive” in the encyclopedia and you’ll
likely find a picture of the tiny zebra mussel. Much like the ruffe, the
goby and the spiny water flea, the zebra mussel arrived as a stowaway
in a ship’s ballast tanks from its original home in the Caspian Sea.
Since the first zebra mussels were discovered in Lake St. Clair in 1988,
they have spread throughout the Great Lakes and across Ontario, Quebec,
as far west as Kansas and down to the Gulf of Mexico.
Thick clusters of zebra mussels have caused extensive and costly damage,
clogging water intakes at treatment plants and hydro stations, and blocking
fire protection piping and cooling systems. In a single season, colonies
of 32,000 mussels per square metre can cover any suitable hard surface,
like a ship’s hull. Small marker buoys can even sink under the weight
of the encrusting mussels. Maintenance becomes a grueling and never-ending
chore.
Extremely efficient filter feeders, zebra mussels can remove much of
the plankton, detritus and other essential food sources at the bottom
of the food web. While they have undoubtedly helped clear murky water,
they have also devastated native populations of mussels, clams, small
fish and everything else that feeds on them. There is even evidence that
zebra mussels increase the availability of PCBs and other pollutants,
leading to higher contaminant levels up the food chain.
Boats and ballast
How do aquatic NIS get here? In less environmentally-enlightened times
some species were released intentionally to improve the local fishing
or to remind a homesick settler of the old country. The coho and chinook
salmon, the rainbow trout and the brown trout were introduced to improve
sports fishing and counter an earlier invasion of alewives. Fish have
escaped from fish farms and hatcheries. Some aquatic NIS are dumped into
the nearest lake along with the other contents of an aquarium or a bait
bucket.
At least one-third of the aquatic NIS that have entered the Great Lakes
did so in the ballast water discharged by ocean-going ships. Once they
have unloaded, large cargo ships refill their ballast tanks with the local
harbour water which includes a complement of the local aquatic life, to
help maintain stability, especially on rough seas. When this ballast
is discharged at the final destination, all of the organisms are released
into the receiving waters.
The Great Lakes-St. Lawrence Waterway is a major international shipping
route that stretches 3,700 kilometres into the heartland of North America.
Some 145 ports and terminals in the basin handle more than 250 million
tonnes of cargo each year. A growing global economy may mean even more
foreign ships docking at Great Lakes ports … and even more aquatic
NIS knocking at our door.
“This is the trickiest issue the commercial shipping industry has
to deal with,” says Captain Rejean Lanteigne, vice president of
operations for the Canadian Shipowners Association. “It affects not
just us, but cruise ships, tour boats, the navy, anybody who sails in
international waters.” The association represents bulk carriers,
tankers and cargo vessels which ply the waters of the Great Lakes and
St. Lawrence Seaway, as well as the Arctic, Maritimes and Eastern American
Seaboard.
A single bulk cargo vessel in the Great Lakes can carry up to 20,000
tonnes of ballast water and contain several hundred different aquatic
species. “The invasion of non-native species is one of the United
Nation’s top five environmental concerns,” says Captain Lanteigne.
“All ship owners recognize this as a serious issue. Once these (species)
are introduced, you can’t prevent their spread, so you have to prevent
their release.”
Flushing and refilling a ship’s ballast tanks with mid-ocean saltwater
while still at sea is currently the most accepted method of control, but
even it is not 100 percent effective. A ship can carry tonnes of unpumpable
slop and sediments in the bottom of its tanks.
Even a vessel that declares it has “no ballast on board” (NOBOB)
can hold a thriving load of aquatic NIS. If such a ship takes on ballast
water in the Great Lakes, it becomes mixed with the unpumpable sludge
and can be released in another part of basin without any treatment or
control. The majority of the ships entering the Great Lakes are NOBOB
– they come in loaded – discharge cargo, then load Great Lakes
ballast on top of the sludge and unpumpable slops.
“You have to worry about the muddy sediments,” says Capt. Lanteigne,
“and, at this point, there is no known (treatment) technology that
is effective and practical. So the testing goes on.” Private and
public sector researchers are investigating a number of promising methods,
including filtration, hydrocyclonic separation, chemical and physical
biocides to eliminate aquatic NIS.
Shipowners are involved in a number of cooperative technology development
programs with the Department of Fisheries and Oceans, Transport Canada,
the U.S. Coast Guard and the International Maritime Organization. The
primary goal is to identify ballast treatment options that might be rapidly
developed for interim application in the Great Lakes, and others more
suited to long-term use internationally.
Battling the sea lamprey
The sea lamprey is a primitive jawless fish that was originally
native to both sides of the Atlantic Ocean. Eel-like in appearance
and growing to almost a metre in length, the lamprey attaches itself
to its prey with a sucking disk and cuts through the scales and
skin to suck out the bodily fluids within. It is estimated that
only one fish in seven survives the attack of the parasitic lamprey.
By the 1940s, the sea lamprey had invaded Lake Erie and the upper
Great Lakes, and quickly precipitated the collapse of the lake trout
and whitefish populations.
In 1954, Canada and the United States signed the Convention on
Great Lakes Fisheries creating the Great Lakes Fishery Commission
to protect the fast-disappearing fish resource base. The Department
of Fisheries and Oceans is the Commission's primary Canadian agent
and has undertaken extensive (and expensive) lamprey control projects
on the gravelly streams and rivers where the lamprey spawn each
spring.
Selective lampricides are used to kill lamprey larvae where they
have burrowed into the stream bed, sterile males are released to
reduce spawning success, and barriers are built to block the upstream
migration of spawning adults. These efforts have helped reduce sea
lamprey populations in the Great Lakes to just 10 percent of their
peak levels in the 1950s. However, it has proven impossible to rid
the basin of the sea lamprey. Once an invading species like the
lamprey has taken hold, the best that can be done is manage its
numbers and, hopefully, lessen its effect on the ecosystem.
Tighter controls on the way
In 1989, the Canadian Coast Guard implemented voluntary guidelines that
require any ocean-going vessel planning to enter the Great Lakes to first
exchange its freshwater ballast with saltwater taken from beyond the continental
shelf. Water in the open ocean contains comparatively fewer organisms
and they are not likely to survive in a freshwater environment.
Similar, though mandatory, requirements based on Canadian guidelines
have been enacted in the United States under its Non-indigenous Aquatic
Nuisance Species Prevention and Control Act in the Great Lakes in 1993.
Every ship entering the Great Lakes system is tested to ensure that its
ballast water has a salinity content of at least 30 parts per thousand.
Canada is currently working to harmonize its regulations with those of
the United States.
Aquatic non-native invasive species are likely to be a growing problem
in the Great Lakes as trade and globalization increase the worldwide spread
of species. Under the new Canada-Ontario Agreement Respecting the Great
Lakes Basin Ecosystem (COA), the Government of Canada will work with the
shipping industry to reduce the entry and spread of aquatic NIS through
regulations targeting the vessels entering the Great Lakes, and new technology
to rid these ships of their unwanted aquatic stowaways.
The individual boat owner and angler has an important role to play in
preventing the further spread of invasive species. Once in the Great Lakes,
aquatic NIS quickly move on to more remote ecosystems and inland lakes
by hitch-hiking on smaller boats and travelling along canals and connected
waterways. Under COA, the Government of Ontario will support outreach
and education programs that will be designed to reduce the movement and
spread of aquatic NIS throughout the basin.
Prevention remains the key. We have to learn our lesson from the zebra
mussel and take strong preventative action now, warns Dr. Dodge, “or
there could be something much worse carried into the Great Lakes tomorrow.”
What you can do!
Whenever you move your boat from one waterbody to another, aquatic
NIS may tag along for the ride. Learn how to identify zebra mussels
and other non-native invasives, and then take the steps to eliminate
unwanted stowaways. To get the latest information and report sightings,
call the Ontario Ministry of Natural Resources’ Invading Species
Hotline 1-800-563-7711,or check out their website at: www.mnr.gov.on.ca/fishing/threat.html.
Since
the 1800s, scientists have identified more than 160 invaders – fish,
crustaceans, aquatic plants and species of plankton – that have successfully
infiltrated and found a permanent home in the Great Lakes. On average,
that is one new species successfully integrating into a delicately-balanced
ecosystem every 11 months. Some are so common, the carp, the alewife,
the lamprey, that many people think they must have always been here. While
some invaders co-exist peacefully with the native inhabitants, about one-in-ten
explodes on the scene like an environmental bomb.
Look
up “non-native invasive” in the encyclopedia and you’ll
likely find a picture of the tiny zebra mussel. Much like the ruffe, the
goby and the spiny water flea, the zebra mussel arrived as a stowaway
in a ship’s ballast tanks from its original home in the Caspian Sea.
Since the first zebra mussels were discovered in Lake St. Clair in 1988,
they have spread throughout the Great Lakes and across Ontario, Quebec,
as far west as Kansas and down to the Gulf of Mexico.