EVALUATION OF OLYMPIA OYSTER (OSTREA LURIDA CARPENTER 1864) STATUS AND RESTORATION TECHNIQUES IN PUGET SOUND, WASHINGTON, UNITED STATES

The Olympia oyster of Washington State, USA (Ostrea lurida dagger) was heavily exploited (1850 to 1940), declined dramatically. and has subsequently failed to recover, although it Still Supports small aquaculture operations. This paper documents the distribution and abundance of O. lurida in one of the last remaining locations where it forms extensive beds: the North Bay Oyster Reserve in South Puget Sound. We monitored recruitment every 2 wk between May and September 2004 and found a small recruitment peak in late July, Which Was Much later than reported for these oysters when they were abundant throughout Puget Sound, We also experimentally tested two factors that could influence recovery: tidal elevation and substrate type. We established 1 m(2) plots at three tidal elevations (-0.3, 0, +0.3 m MLLW) with six Substrates: bare. gravel. Crushed shell of Crassostrea gigas (Pacific oyster), whole C. gigas shell, whole shell of O. lurida, and live O. lurida. The Plots Were Set LIP May 21 2004 and measured for recruitment oil October 16, 2004 and April 11, 2005 by collecting material from a 0.0125-m(2) area of each plot. Recruitment improved at low tidal elevations and differed across substrates. Ostrea lurida shell consistently provided a better recruitment substrate than gravel or bare plots, but shell treatments could not be distinguished statistically. Postrecruitment mortality Occurred in all treatments; however the rates of mortality were not significantly different by elevation or substrate treatment. Habitat restoration (low intertidal and subtidal shell areas) should promote the recovery of O. lurida where natural recruitment still occurs.