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Grand Haven students participate in annual fishing event
Grand Haven Tribune (5/15)
In Michigan, Grand Haven Area Public Schools partnered with a nonprofit organization called Pursuing a Dream to give about 300 students with special needs the opportunity to fish and enjoy the outdoors.

NYPA funding aids three St. Lawrence River projects
Watertown Daily Times (5/10)
The St. Lawrence River Research and Education Fund has provided funding for three projects that support environmental education in and around the riverís ecosystem.

Lake Michigan Academy students learn from 'Salmon in School' project
MLive (5/9)
About 100 schools throughout Michigan are selected to take part in the Lake Michigan Academy program that aims to help stock local rivers and support fishing as a leisure activity.

Huron Perth students find Lake Huron threats
Blackburn News (5/1)
Nearly 60 high school students from the public and separate boards in Huron and Perth counties spent one day at the Oakwood Inn in Grand Bend, Ontario, where they were learning about the environmental threats and challenges to Lake Huron.

Bay City tall ship sets sail for season of education, fun
The Associated Press (4/24)
An educational tall ship is back for another season on the Lake Huron waters off Bay City, Mich.

Salmon raised in Guelph classroom soon to swim in Lake Huron
Guelph Mercury (4/22)
Schools in Ontario are participating in the Lake Huron Fishing Club's salmon hatchery program, which aims to rejuvenate a salmon population that has been severely diminished.

TEACH Calendar of Events
What's going on in your neighborhood this month? Meet other people and learn together at recreational and educational events! Our new dynamic calendar is updated daily with current educational events.
TEACH Invasive Species

4 | How do invasive species get here?

Ballast transport
Ballast water is fresh or saltwater (sometimes containing sediments) held in tanks and cargo holds of ships. Ballast water is pumped onto ships at different ports of call to add weight to ships that may be carrying little or no cargo. These ships are considered to have "ballast on board" (BOB). Ballast water release. Click to see larger image.The added weight of the ballast water causes the vessel to sit lower in the lakes or ocean, thus providing stability and maneuverability during voyage and clearance under structures, such as bridges, in waterways. Even ships that have "no ballast on board" (NOBOB) may have water and sediments that could not be completely pumped out of the ballast tanks.

Once NOBOB and BOB ships arrive in another port of call, the water held in ballast tanks is discharged, exchanged or water is added. This ballast exchange may occur at multiple ports of call during a vessel's long journey. Larger vessels often carry millions of gallons of ballast water and, with more than 80 percent of the world's commodities carried on ships, that is a lot of water traveling around the globe every year!

But it is not only water or sediments that goes into ballast tanks. When ballast water is pumped into the ship at a port, it includes organisms found in that port. These organisms range in size from microscopic phytoplankton and zooplankton to crabs and fish. According to MIT Sea Grant, it is estimated that as many as 3,000 exotic species are carried in ships' ballast every day around the globe.

Those organisms that survive the trip are ultimately released when the ballast water is discharged at the final port destination. In many cases, the nonindigenous species are not kept in check by the indigenous predators and competitors they might find in their native waters. Therefore, they have a very good chance of increasing their population and out-competing native organisms for food and space. Though not all species brought in ballast water have disastrous effects on the Great Lakes (or even survive the trip), zebra mussels are a good example of the ecological and economic damage ballast-borne invasive species can cause.

Other routes of invasion
Although ballast water is considered the primary pathway of invasion into the Great Lakes, nonindigenous species have been introduced to the lakes in the following ways:
  • removal of physical barriers during the building of canals (such as the Chicago Sanitary and Ship Canal)
  • accidental introduction or unintential release of organisms through aquaculture ("fish farming"), the aquarium trade, or the use of exotic bait for fishing
  • through the stocking of sport fish

Graphic: Ballast water release. Courtesy L. David Smith/MIT Sea Grant.

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