The Scope of the National Aquatic Hitchhiker Problem
National Recognition of the Emerging Problem:Since the aquatic hitchhiker issue first gained notoriety in the Great Lakes region, initial efforts to reduce the continued spread were centered in that area. However, subsequent research has indicated that aquatic nuisance species are a problem for many ports and inland waterways of the U.S. In 1996, Congress acted upon these finding and re-authorized the original federal legislation by enacting the National Invasive Species Act. This law expanded the scope of the issue beyond the Great Lakes and required the Coast Guard to establish national voluntary ballast water guidelines. In July of 1999, the National Voluntary Guidelines were implemented for all waters of the United States.
ANS Hotspots around the country:As the issue has emerged and has become better understood by resource professionals, the impacts across are becoming more widely known. As a result, various regions have been identified as areas that are highly susceptible to aquatic hitchhikers.
- San Francisco Bay, a center of extensive international trade, hosts more than 210 introduced aquatic species. For nearly 150 years, this highly disturbed and vulnerable ecosystem has been exposed to continuous, large-scale introduction of non-native species through activities associated with commercial shipping and oyster farming. The importation of commercial oysters has allowed non-native species to hitchhike on the shells of oysters and packing materials shipped from the eastern U.S. coast and Japan. In the last decade, a new species has arrived about every 12 weeks.
- In Chesapeake Bay, an area where large quantities of foreign ballast water are discharged, it is estimated that more than 100 harmful non-native aquatic species are established in the bay.
- Ecosystems of Pacific and Atlantic coastal waters suffer from infestations of the European green crab, a harmful hitchhiker that preys on commercially valuable oysters and clams. In the Pacific Northwest, the list of introductions is growing rapidly due to ballast water.
- In the Gulf of Mexico, the marine brown mussel, displaces native mollusks and threaten mangrove communities. Like the zebra mussel, the brown mussel encrusts hard surfaces. As its range expands, there is rising concern over the economic impacts that could result from fouling of water intake systems, shipping areas and offshore oil platforms.
- Inland waters. Once introduced into the Great Lakes or coastal waters, many hitchhikers spread to inland lakes, rivers, wetlands and waterways by way of barges, recreational users, bait buckets, fish stocking and other human-assistedtransport mechanisms. The zebra mussel, hydrilla, and others have taken great advantage of these opportunities to hitch a ride and have proved to be devastating to freshwater lakes and rivers. (Adapted from the Great Lakes Regional ANS Panel, "Biological Invasions," 1988)
How aquatic nuisance species are introduced and spread
- Maritime Commerce - The single largest introduction source of aquatic hitchhikers is via transoceanic cargo ships originating at foreign ports. Some species attach themselves to the hulls of ships, while others are carried in ballast water taken on by ships in foreign ports for stability. When ships reach their destinations, the non-native species are released with ballast water discharge. Over the past century, as shipping time has become shorter with faster vessels, and as harbors have become less polluted, more species have been able to survive the journey and thrive when introduced into new waters. With continued expansion of international trade, new ANS introductions are likely to occur from waters around the globe.
- Recreational boating and other water related recreational activities - Once established in some U.S. waters, nuisance species can be easily spread to more lakes, rivers and coastal resources by those who use the water. They can hitch a ride on boats, trailers, fishing waders, scuba equipment or clothing, seaplanes, buckets used by children playing in the water or anglers who use them for a variety of reasons, and many other ways. By following a few simple procedures, recreational users can easily eliminate their role in the spread.
- Sportfish stocking - Whirling disease, a potentially fatal condition that manifests itself in young salmon and trout, is caused by a non-native parasite that infects the fish cartilage and nervous system. Ultimately, the parasite causes these fish to swim in a circular pattern making them susceptible to predation. Transmitted by infected stocked trout, whirling disease has damaged hatchery-reared fish stocks across the country as well as wild stocks in inland water of the United States.
- Accidental releases from the Aquaculture and Horticulture industries, the Aquarium trade and the Live Bait business - Each of these specialized economic sectors depends partly upon the importation and/or movement of live, non-native fish and aquatic plants for their bottom line. As the fastest growing agriculturally-related segment of our economy, fishery researchers and managers have expressed an increased level of concern about these commercial shipments. Aquarium fish, wild-caught fish, aquaculture and horticulture products are all transported using water as a medium. While the various live species are a concern, the water used to transport these shipment also could serve as a pathway for the spread of aquatic nuisance species.
This infomation was provided by the U.S. Fish and Wildlife Service. For more information, go to their campaign website www.protectyourwaters.net.