In 2011 the GWI undertook a pilot project to survey the subtidal population of the native Olympia oyster (Ostrea lurida) in the Gorge and Portage Inlet. This is a federally designated “species of special concern” and one of the few remaining populations on the BC coast occurs in the Gorge Waterway.

Several survey methods were tested to determine the most accurate way to assess population densities and to map the distribution of the oyster. Densities were found to be among the highest recorded on the BC coast, at 450/m2. The survey methods tried were surface viewer, underwater video, free swimming divers and scuba divers. The most accurate method turned out to be using scuba divers; this reduced the error from counting dead oysters whose shells can remain attached to the substrate for many years.

In 2020 and 2021, World Fisheries Trust/Coastal Collaborative Sciences carried out further surveys of Olympia oysters in the Gorge and Portage Inlet, and added 11 new sampling sites, including some in the Inner Harbour. Olympia oysters were found at 35 of 46 sites, with presence increasing as the survey moved from the Inner Harbour to Portage Inlet. For more information, view the final report from 2021.

These projects are adding to our understanding of the habitat needs of Olympia oysters, potential threats posed by invasive marine species and other factors that affect the distribution and abundance of the Olympia oyster in the waterway.