Thinking Strategically in the Aleutian Archipelago

Each year, thousands of deep-draft vessels transit through the Aleutians along shipping routes between North America and Asia. In December 2004 the M/V Selendang Ayu, a 740-foot bulk carrier, lost power and drifted aground on the north shore of Unalaska Island in the eastern Aleutians. The vessel was broken in two, spilling over 300,000 gallons of heavy fuel oil and cargo of soybeans. The resulting disaster claimed the lives of six crewmen, as well as thousands of seabirds and at least six sea otters. Our comprehensive analysis of North Pacific shipping routes through application of data from the Automatic Identification System (mandated by the International Maritime Organization for these deep-draft vessels), has documented that many of these ships pass perilously close to several of the Aleutian islands. Our results helped inform a proposal by the U.S. Coast Guard to the International Maritime Organization for the establishment of five Areas to be Avoided (ATBAs) in the Aleutians. These ATBAs would apply to ships 400 gross tons and heavier, transiting on the Great Circle Route on either the north or south side of the Aleutian archipelago. The proposal was approved by the IMO in June 2015 and takes effect on January 1, 2016. Further analysis of new vessel routes that would conform to the proposed ATBAs using distance as a proxy for exposure indicates that the new routes would reduce potential risk to seabird colonies by 17% and to endangered Steller sea lions at haulouts and rookeries by 21%, while adding less than 1% to the overall length of the voyage between the two continents. Additional analysis supported by the ABSI/WCS partnership will identify areas most at risk to vessel drift groundings, which can inform spill response preparation efforts. There are enormous economic benefits for vessel operators to reduce the risk of impacts to natural resources such as marine mammals and seabirds.