NOAA issues modified marine mammal permit for Sitka cutter dock

Pile driving for the Coast Guard's new cutter dock in Sitka will use plastic fender piles instead of steel, shrinking the underwater zones where marine mammals could be disturbed. NOAA Fisheries finalized the modified incidental harassment authorization on Aug. 3. It is good for one year and no later than Aug. 3, 2027.

The original authorization ran from Sept. 1, 2026, through Aug. 31, 2027. The new expiration date cuts nearly a month off the back end, even though in-water work at Moorings Sitka is still expected to continue into September 2027.

The main construction change is the fender piles. The contractor switched from 16-inch steel to 14- to 16-inch plastic, which put out 162 decibels at 10 meters, 1 decibel less than steel. That shrank the Level A and Level B harassment zones. Installation time drops from 30 minutes per pile to 15. The daily rate rises from five piles to six, with a ceiling of eight.

The count of 60 fender piles, the vibratory method, and the species and stock scope are unchanged. So are the mitigation, monitoring and reporting requirements, including the previously established shutdown and harassment zones.

The pile substitution itself did not change the take estimates, because NOAA Fisheries estimated take from species occurrence rather than noise footprint. Separately, the agency corrected a rounding error that had put total Level B humpback harassment at 61 instances, reducing it to 60, and set the Hawaii stock's share at 59 instances. It also revised its killer whale math, now assuming all 106 authorized takes could fall on any one of four stocks.

The agency found negligible impact on affected species and no unmitigable adverse impact on subsistence. It categorically excluded the modification from further review under the National Environmental Policy Act.

The NOAA Fisheries Alaska Regional Office issued a Biological Opinion on July 28 finding no jeopardy to the endangered Western distinct population segment of Steller sea lion or the threatened Mexico-North Pacific humpback whale stock. No public comments were received.

The Marine Mammal Commission, in a July 2025 letter on a related Fish and Wildlife Service rule for Coast Guard work in Seward, Sitka and Kodiak, said the injury thresholds regulators use "are outdated." The commission also noted the Coast Guard would need to consult potentially affected Alaska Native communities.

Alaska Native communities in Southeast Alaska, including Sitka-area subsistence users, have an identified interest in the work. Construction noise and access restrictions can alter the distribution and behavior of marine mammals they rely on, the basis for the federal consultation and plan-of-cooperation requirements. Commercial and subsistence users in the Sitka marine area could likewise see changes in marine mammal presence from pile driving and drilling.