Keeping Invasive Species Out Of The Great Lakes

Both nations should ensure that only vessels adhering to these standards gain access to the lakes, and binational surveillance measures should be in place to monitor the presence of aquatic invasive species.  These actions should be part of a suite of preventive measures designed to evolve over time in response to practical experience and technological advances.  The committee that wrote the report also stated that many of its recommendations could be enacted within the next two to three years.  Delaying beyond this time frame would leave the Great Lakes, which are already home to over 180 aquatic invasive species, in danger of future invasions.

Ships from the Atlantic Ocean and beyond enter the Great Lakes -- Ontario, Erie, Huron, Michigan, and Superior -- via the St. Lawrence Seaway, a series of channels and canals dredged to allow deep-draft shipping vessels access to ports within the lakes.  The seaway, which is managed jointly by the United States and Canada, opened for international maritime trade in 1959, and since that time the number of invasive species in the lakes has risen markedly.  

Many entered the lakes in ballast water, which is taken on board empty ships to provide stability; when ships pick up cargo, they pump out their ballast water, along with any aquatic species it contains.  If conditions are favorable, a foreign species can multiply quickly in its new location and may wreak havoc on the local ecosystem.  Even ships that arrive in the seaway full of cargo, having emptied their ballast water at a previous port, could still be carrying invasive species within their ballast tanks.

Since the opening of the seaway, ballast water has been the source of 55 percent to 70 percent of the aquatic invasive species in the Great Lakes, including the zebra mussel, one of the most successful invaders to date.  In addition, invasive species can enter the lakes via recreational boating, bait fishing, disposal from home aquariums, and many other avenues.  Because there are so many ways that an invasive species can enter the lakes, even closing the St. Lawrence Seaway altogether would not stop future invasions, and closure of the seaway would not enhance regional trade.  Therefore, the best option is to require ballast water management by all international ships entering the seaway as well as ships coming from the coasts of the U.S. or Canada, the report recommends.

Because the Great Lakes are a freshwater ecosystem, one method ships use to kill potential invaders is to either fill or flush out their ballast tanks with saltwater, which kills freshwater species.  Another option is to use water treatment, such as filtering the ballast water or adding chemicals to it.  Although the effectiveness of these water treatment systems is believed to be greater than that of saltwater, most of these technologies are currently either unproven or technically challenging onboard ship, said the committee.

A number of ballast water management regulations are already in place within the Great Lakes region.  However, Canada and the United States have different requirements, and the United States allows states to set their own standards.  Michigan has adopted specific requirements for ships accessing its ports, and other states are considering following suit.  These inconsistencies can create confusion within the shipping industry and make monitoring compliance difficult.  According to the committee, the entire Great Lakes region should have a uniform set of standards for combating invasive species.  The United States should also adopt ballast water management standards identical to those proposed by the IMO, which require specific saltwater exchange or flushing protocols and monitoring for organisms after treatment.  Canada adopted regulations identical to the IMO rules in 2006, but the United States is still considering legislation options.

Although there have been calls for the United States to follow standards even stricter than the IMO's, the committee noted that cost-effective, accurate tools do not yet exist to monitor effectiveness or compliance with standards beyond those of the IMO.  The uncertain and inconsistent nature of the Great Lakes current regulatory environment might even hinder technological development of water treatment and monitoring compliance, said the committee.  Adopting uniform requirements would remove that uncertainty, and innovative technology may develop more quickly if a clear market exists. 

Uniform ballast water standards in the Great Lakes could be the first step in converting a system currently fragmented between two nations and multiple agencies into a comprehensive, cooperative, and coherent binational system of governance.  The committee also recommended that the United States and Canada develop a joint surveillance and eradication program to monitor and eliminate any new invasive species that appear in the lakes.  Invasive species legislation affecting the Great Lakes could then be modified uniformly to strengthen or discontinue policies based upon efficacy, and to adapt legislative policy to technological advances.

The report Great Lakes Shipping, Trade, and Aquatic Invasive Species is available at: http://trb.org/news/blurb_detail.asp?id=9267

The study was sponsored by the Great Lakes Protection Fund.  The National Academy of Sciences, National Academy of Engineering, Institute of Medicine, and National Research Council together comprise the National Academies, which operates under a congressional charter.  The Research Council is the principal operating agency of the National Academy of Sciences and the National Academy of Engineering.