A recent study has identified hot spots along the Aleutian Islands where the potential is high for large numbers of seabirds to be harmed by shipping-related oil pollution.
It's well documented that the Aleutians are home to millions of seabirds. It's also no surprise that the region sees thousands of ships travel through its waters each year, many carrying large quantities of fuel, and, as a result, the potential for an oil spill at sea. But until recently, the overlap of where ships travel the most and where seabirds live had not been studied.
Martin Renner of Tern Again Consulting has spent the last two years looking at seabird and shipping data, creating maps that show the places in the Aleutians where there is the highest likelihood for a shipping disaster to impact a large number of birds.
"When everything comes together, and you have lots of seabirds and lots of ships, there is a high likelihood for birds to get exposed to oil," Renner said.
Renner noted that the risk from oil exposure isn't just from a large oil spill but also from chronic oil pollution caused by small amounts of oil being pumped into the ocean through illegal activities such as ships cleaning their tanks or emptying their bilge water into the ocean. Little monitoring of that chronic oil pollution is being done at this point but data from this study could be used to target areas to watch, he said.
Renner said he used data of seabird observations at sea, gathered for studies and compiled into a large database by the U.S. Geological Survey, going back as far as the 1970s. From this data, he built a model that showed the density of bird populations throughout the year; some regions had bird populations year-round but others were more seasonally populated by seabirds.
Determining shipping activity in the region required some creative data collecting, as radar tracking of vessels is not possible in many areas along the Aleutians. Renner used data from automatic weather monitoring devices that are placed on many vessels traveling the region. These automated weather reports -- made every few hours from the ships -- allowed Renner to extrapolate shipping traffic density in various locations.
When all the data was entered, Renner found some expected spots where large seabird populations were being passed by high numbers of large vessels, as well as some areas that were more of a surprise.
Unimak Pass east of Dutch Harbor was an obvious hot spot, Renner said, since the vast majority of ships traversing the chain go through the region. In addition, high densities of birds are found along Unimak Pass throughout the year, though the summer months are particularly busy.
"It's a well-known bottleneck," he said.
But a lesser-known point of interest found in the study was south of Sanak Island, where the ships that leave Unimak Pass cross over waters at the edge of the continental shelf. Here, Renner said, there is a lot of seabird activity because of nutrients coming up from the deep waters of the ocean floor into the shallower waters surrounding the Aleutians.
"There is a lot of biological activity here," Renner said. "That spot wasn't really known."
Other areas, such as the western Aleutians near the north end of Attu and Kiska islands, were at high risk only in the summer, he said.
The study, funded by a grant from the Fish and Wildlife Service, could be used to assess where to place response equipment, Renner noted. Placing response equipment in a location like Adak, for example, would mean response times of several days to those critical areas with high concentrations of shipping traffic. Sand Point, where response times are only a few hours to many of these high-risk locations, would be better based on this study, he said.
Renner said all the data from the study will be available online soon.
This story first appeared in The Bristol Bay Times/Dutch Harbor Fisherman and is republished here with permission.