Great Lakes Maritime Act of 1981

Great Lakes Maritime Act of 1981 - Title I: Restructuring the Financing of the Saint Lawrence Seaway Development Corporation - Amends the Act establishing the Saint Lawrence Seaway Development Corporation to require such Corporation to pay excess revenues into the general fund of the Treasury.

Directs the Corporation to establish tolls so that the rate of return on the United States' investment in the Saint Lawrence Seaway will be equal to the rate of return on the Canadian investment in the Seaway.

Cancels the balance owed by the Corporation on bonds issued to the Secretary of the Treasury.

Title II: Equitable United State Flag Service for Great Lakes Ports - Amends the Merchant Marine Act, 1936, to direct the Secretary of Commerce to establish trade routes, services, or lines that take into account the seasonal closure of the Saint Lawrence Seaway and that provide for alternate shipping routes via a different range of ports during such closure.

Title III: Regulation of Common Carriers by Water - Amends the Shipping Act, 1916, to redefine the term "common carrier by water in foreign commerce" to include persons engaged as common carriers in specified ocean transportation of property who: (1) advertise, solicit, or arrange, within the United States, for such transportation; or (2) issue or deliver ocean or through intermodal bills of lading or other contracts of affreightment for such transportation.

Directs that specified contracts or agreements be filed with the Federal Maritime Commission within 30 days after finalization.

Directs such common carriers by water to file their tariffs with the Commission within 30 days of the date of enactment of this Act. Sets forth the effective dates of such tariffs.

Title IV: Environmental Study of the Great Lakes - Creates an interagency task force to study the environmental and ecological effects of a specified program that would extend the navigation season of Lakes Erie, Huron, Michigan, and Superior. Directs the task force to submit reports to specified Congressional committees within certain time constraints.

Directs the Secretary of the Army, through the Chief of Engineers, to study: (1) island transportation needs on the Saint Mary's and Saint Clair Rivers; and (2) the extent of damage related to a specified program extending the navigation season on the Great Lakes. Requires the Secretary to report on such studies to certain Congressional committees by June 30, 1983.

Authorizes appropriations to carry out such studies.

Title V: Study of Shoreline Erosion Related to Regulation of Lake Superior by International Joint Commission - United States and Canada - Directs the Secretary, in cooperation with other departments, agencies, and instrumentalities of the United States, and with State and local governments, to survey the extent of shoreline erosion damage in the United States causally related to the regulation of the waters of Lake Superior by the International Joint Commission - United States and Canada. Requires a report on such findings to Congress before September 30, 1983.

Authorizes appropriations for such study.

Title VI: Amendment to the Great Lakes Pilotage Act of 1960 - Amends the Great Lakes Pilotage Act of 1960 to limit the liability for negligent torts of United States registered pilots to $1,000.