Dungeness crab survey for the Southwest Ocean Disposal Site and addtiional sites off Grays Harbor, Washington, June 1991

Abstract

As part of the Grays Harbor Navigation Improvement Project, the US Army Corps of Engineers, Seattle District (USACE), has made active use of the Southwest Ocean Disposal Site off Grays Harbor, Washington. Disposal site boundaries were established to avoid an area where high densities of Young-of-the-Year (YOY) Dungeness crab, Cancer magister, were observed during the site selection surveys. To monitor possible impacts of disposal operations on Dungeness crab at the site, USACE recommended a crab distribution survey prior to disposal operations in the February 1989 environmental impact statement supplement (EISS) as part of a tiered monitoring strategy for the site. According to the tiered monitoring strategy, a preliminary survey is conducted to determine if the disposal site contains an exceptionally high density of YOY Dungeness crab. The trigger for moving to a more intensive sampling effort is a YOY crab density within the disposal site that is 100 times higher than the density in the reference area to the north. This report concerns a 1991 survey that was designed to verify that the density of YOY Dungeness crab present at the disposal site was not exceptionally high. Another objective of the survey was to estimate Dungeness crab densities at nearshore areas that are being considered as sediment berm sites by USACE.