Invasive Species 101
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Great Lakes / St. Lawrence Seaway entities are working together to combat the entrance of invasive species into the waterway's ecosystem. To view a newsreport on this effort CLICK HERE. For more information on the threat posed by invasive species, read on.
FAQ - INVASIVE SPECIES
What are aquatic invasive species and why are they a problem?
An aquatic invasive species (AIS) is an aquatic species that is not native to the ecosystem under consideration and whose introduction causes, or is likely to cause, economic or environmental harm or harm to human health. Invasive species are considered a nuisance because they may alter the existing biological, chemical, or physical processes of an ecosystem in a way that reduces our ability to derive important benefits from that system. 
What is the cost of invasive species in the Great Lakes and St. Lawrence Seaway (GLSLS) System?
The total environmental and economic cost of invasive species in the GLSLS system is difficult to assess, though it is generally accepted that there is considerable environmental cost associated with AIS and the problem requires aggressive management measures. There is no standardized protocol for measuring the costs of AIS, and therefore estimates vary widely.
What is ballast water and how is it related to the problem of invasive species?
Ships use ballast water to adjust their stability and trim when sailing without cargo or only partially loaded. Ships that are laden with cargo carry little or no ballast water in their ballast tanks, and are referred to as “NOBOBs” (NO Ballast On Board). Ships with no cargo on board need ballast water to help stabilize the ship during transit, and are referred to as “BOBs” (Ballast On Board). The use of ballast water therefore is critical for the safe operation of a vessel.
At the same time, it has been established that both ballast water and the sediment in NOBOB tanks are vectors for AIS, - meaning they can serve as mechanisms by which AIS organisms move from place to place. Recognizing the importance of controlling the spread of AIS, commercial shipping interests are highly motivated to find ways to drastically reduce or eliminate the introduction of these organisms through ballast water. To that end, ship operators have been following Best Management Practices, regulations, and other guidelines for many years.
Is ballast water the only vector for AIS introduction into the GLSLS ecosystems?
There are many vectors besides ballast water that have been identified as significant mechanisms for AIS introduction into the GLSLS. Other vectors include recreational activities, such as boating; opening new waterways between previously separate ecosystems, such as through the creation of canals; intentional stocking; and the release of live animals or plants from aquaria.
How many AIS have been introduced into the GLSLS system through ballast water?
Because most species are detected only after they have already established a successful population, it’s practically impossible to know exactly where or when a species was introduced. Determining the vector by which a species was introduced requires analyzing a variety of factors, including an organism’s physical characteristics, its growth and development stages, and the vectors available to it. Speculation on whether a species was introduced via ballast water usually relies in part on the existence of the organism in an area from which transoceanic vessels come into the Great Lakes. Since the opening of the Seaway in 1959, it is estimated that as much as 65% of aquatic non-native species entering the Great Lakes have been introduced via ballast water.
Has the rate of species introduction into the GLSLS been increasing?
While documentation of the introduction of new species has been increasing, it is difficult to objectively determine the actual rates of introduction. The rate of discovery of new species in the Great Lakes has increased, but this may in part be an artifact of the natural time lag between a species introduction and its discovery, coupled with an increasing amount of attention being paid to looking for undocumented species and understanding the native environment .
What is VHS and how is it related to ballast water?
Viral Hemorrhagic Septicemia (VHS) is a fish virus that recently has been recorded within the Great Lakes. Genetic research has suggested that coastal Canadian and U.S. fish populations are the likely source of the Great Lakes strain. Scientists believe the most common means of transmitting the virus is by fish-to-fish contact. Although ballast discharge is one of several possible mechanisms for further dispersal of VHS, it is not considered the most effective vector. To date, no scientific studies have shown that VHS or any other viral diseases were introduced by ballast water.
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