National Aquatic Invasive Species Act of 2003

National Aquatic Invasive Species Act of 2003 - Amends the Nonindigenous Aquatic Nuisance Prevention and Control Act of 1990 to establish aquatic invasive species prevention requirements for all vessels operating in U.S. waters. Requires the Secretary of the department in which the Coast Guard is operating to promulgate regulations for ballast water management standards and certification procedures.

Directs the Aquatic Invasive Species Task Force to establish a priority pathway management program that identifies those pathways that pose the highest risk for the introduction of aquatic invasive species unless further managed.

Prohibits the importation of live aquatic organisms not in trade without specified screening and approval.

Requires the Assistant Secretary of the Army for Civil Works, with the concurrence of the Administrator of the Environmental Protection Agency, to construct and maintain a national dispersal barrier program to prevent the spread of aquatic invasive species in U.S. waterways.

Provides for expansion of the Brown Tree Snake Control Program and Aquatic Nuisance Species Program information, education, and outreach activities. Requires the Task Force to establish a national subcommittee on nutria for its control.

Requires the Invasive Species Council to coordinate with the Task Force to combat aquatic invasive species. Requires the Task Force to recommend to appropriate Federal agencies additions to the list of aquatic invasive species.

Requires the Task Force, the Council, and the Secretary of State to coordinate activities to ensure that international efforts to prevent and manage aquatic invasive species are coordinated with U.S. policies.