Vessel Traffic Overview

Updated:October 9, 2009 14:52

Summary

 

Vessel tracking data provided by the automated identification system (AIS) receiver at Scotch Cap, Unimak Pass has allowed us to significantly revise and improve the original Aleutians Vessel Traffic Study published in April 2005. In addition we have increased our confidence in vessel profiles by type (container, bulk cargo, etc.) by expanding the number of vessels used to develop this profile. However, this is not an exact vessel traffic study and our estimations have some limitations. No single data set contains all the current information needed regarding number, type, size, and fuel capacity or casualty history for vessels transiting the Aleutians Subarea. Information gathered from the many sources used in this report is presented in various forms that are not always comparable. For example, the U.S. Coast Guard and State of Alaska use dissimilar vessel classification schemes. In some cases, similar, but not exact, datasets were compared or combined in order to provide the best possible estimates. Despite these limitations, it is possible to make some summary statements about Aleutian vessel traffic.

Figure 16 shows a combination of many vessel traffic elements presented in the other figures. Clearly, a wide variety and large number of vessels transit the Aleutians Subarea. We estimate that over 3,100 ships pass through the Aleutians each year on trans-Pacific voyages. Over a third of these transits are by container ships with a typical fuel capacity of 1.6 million gallons of fuel oil. Over 40% are bulk and general freight ships with a median fuel capacity of 470,000 gallons or a capacity similar to the amount of fuel carried by the Selendang Ayu when it broke apart in December 2004. The predominant fuel type in these large vessels is persistent fuel oil, which represents a significant environmental threat if spilled. Few tank ships sail through the area, about 20 voyages a year, and some are in ballast.

About 400 Aleutian port calls are made by ships. About 130 of these port calls are container ships with a typical fuel capacity of 1.6 million gallons of persistent fuel oil. About 110 port calls are made by refrigerated (reefer) ships with a typical fuel capacity of about 320,000 gallons of mostly persistent fuel oil. The remaining port calls are mostly tugs towing barges. Passenger vessels represent a very small component of the Aleutian vessel traffic.

About 300 million gallons of non-persistent fuel oil is moved into and through the Aleutians as cargo for use in Alaska in about 130 voyages onboard tank barges and in a single tank ship.

About 400 fishing vessels operate in the rich Aleutian fisheries that are valued in excess of 1.5 billion dollars. Fishing vessels typically have a fuel capacity about 30,000 gallons and almost all carry non-persistent fuel.

There are four ocean-going tugs resident in the Aleutians and almost 200 tug voyages each year that transit the area with barges in tow.

Four hundred and eighty-six (486) casualties affecting seaworthiness of US vessels were reported in the Aleutians from 1990 through July 2006. US vessels reporting casualties were usually smaller than foreign vessels and primarily fishing vessels.
Forty-eight (48) casualties affecting seaworthiness of foreign vessels were reported in the Aleutians from 1991 through July 2006. These reports included 17 loss of maneuverability incidents. We believe that foreign vessel casualties are under reported.

Data was assembled from 43 oil spill events that occurred between 1981 and 2006. These spills totaled almost one million gallons. Sixty-two percent of the amount spilled was non-persistent oil and 38 percent was persistent oil.

Most of the 400 vessels calling at Aleutians ports and many of the larger fishing vessels hold State oil spill contingency plans and certificates of financial responsibility. However, the great majority of the 3,100 vessels transiting the Aleutians have no State oil spill contingency plans and no State certificate of financial responsibility, because they are traveling in innocent passage. Most of these unregulated vessels carry persistent fuel oil, which unlike diesel fuel, will persist as floating or beached oil for days to months.

Recommendations for Additional Study

After reviewing the information available on marine vessels transiting the Aleutians, we have the following recommendations for additional investigation:

• Conduct a more detailed review of Coast Guard casualty reports, particularly foreign vessel reports, to determine the underlying root-cause of accidents; particular attention should be given to incidents involving loss of maneuverability and whether timely communication and intervention could prevent vessel groundings;
• Categorize the fishing vessels operating in the Aleutians by relative risk. For example, fish processors are typically large, relatively under-powered, and operate for long periods close to shorelines.