Report: Rate of introduced species in U.S. waters continues to rise

A 'game of ecological roulette' is being played along our coasts as hundreds of invasive species arrive each day by way of ships' ballast waters, fishing activities, and other means, a new report presented to the Pew Oceans Commission shows.

Cargo ships, home aquaria contribute to growing threat to coastal ecosystems

Oct. 25, 2001 — The historic battleship USS Missouri is moved from Puget Sound to Hawaii, carrying mussels that recolonize on a nearby submarine. Marina floats are towed from New Jersey to Massachusetts, along with a population of Asian crabs. Atlantic salmon reproduce in the Pacific Northwest after escaping from fish farms. An owner of a home aquarium releases Mediterranean green seaweed into a lagoon near San Diego, to an established population of this green algae.

So begin the latest chapters in the ongoing story of a growing threat to U.S. coastal waters: introduced species. These tales are more than just curiosities. Introduced species crowd out native species, alter habitats, disrupt nature's balance, and impose economic burdens on coastal communities.

In a report entitled Introduced Species in U.S. Coastal Waters presented to the Pew Oceans Commission, James T. Carlton, Ph.D., of Williams College and Mystic Seaport, describes a "game of ecological roulette" playing out along our coasts as hundreds of species arrive each day by way of ships' ballast waters, fishing activities, and other means.

Carlton details that the rate of marine introductions has risen exponentially over the past 200 years and shows no sign of leveling off. He highlights the loss of coastal habitat and biodiversity and the millions of dollars spent each year to research and control introduced species. Carlton recommends a compulsory ballast water management program, an early-warning and rapid-response system, and greatly expanded research and public education programs.

"Once an introduced crab, fish, or seaweed takes hold in a coastal area, it can cause tremendous environmental disruption and result in millions of dollars in damage," said Leon E. Panetta, chair of the Pew Oceans Commission. Panetta is an independent group of leaders on a national review of the policies needed to restore and protect the oceans' living resources. "For coastal areas already threatened by polluted runoff, poorly planned coastal development, or declining fisheries, the effects of introduced species are especially damaging," Panetta added.

Carlton's report begins with a look at why introductions continue to occur along our coasts and how they affect our ability to restore and protect coastal habitats. He then discusses the primary sources of introductions, including ballast water and fouling organisms (those that attach to ships and other structures), maritime activities such as exploration and commerce, fishing activities, and the aquarium industry. He concludes with a review of efforts to prevent, reduce, and control introductions and offers several recommendations for action.

"The management of introductions should be tackled from the point of origin to the point of arrival," concludes Carlton. "We must prevent and reduce invasions, coordinate response to newly discovered introductions, expand research, and improve public awareness of the problem."

To assist in its deliberations, the Pew Oceans Commission has contracted with a number of distinguished scientific and technical experts to prepare reports on key marine resource issues. Authors review the latest information and offer recommendations on how best to address the ecological, economic, political, or social problems they identify.

Carlton's report is the third in a series that includes reports on marine pollution and aquaculture. Additional reports on coastal development, fishing, and marine protected areas are underway.

The Pew Oceans Commission was formed in May 2000 with a grant from the Pew Charitable Trusts and has held public meetings in Washington, D.C.; Monterey, Calif.; Maui, Hawaii; Charleston, S.C.; Rockport, Maine; and Anchorage, Alaska. The commission's next meeting will take place in New York City on November 28-30. The commission includes leaders from ocean research, fishing, conservation, industry, and government. In addition to introduced species, the commission is reviewing coastal development, marine pollution, fishing, aquaculture, ocean governance, and marine protected areas. The commission will issue its formal recommendations to the President and the Congress next year.

Introduced Species in U.S. Coastal Waters: Environmental Impacts and Management Priorities is available online at or by calling 703-516-0624. To receive a PDF version, e-mail Jessica Riordan at

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