Bulkhead Removal Forage Fish Spawning Survey

King Conservation District has implemented a novel bulkhead removal project along the Puget Sound shoreline near Three-Tree Point in Burien, WA to improve habitat for forage fish species critical to the Puget Sound ecosystem. The project treatment included the removal of an existing timber bulkhead, followed by the installation of boulders, partially embedded large wood, and the planting of native vegetation. It is anticipated that this form of soft-shore armoring will allow for more natural sediment processes to occur, thereby improving site potential for forage fish spawning. Wild Fish Conservancy designed and implemented a Before-After-Control-Impact assessment of the project, sampling for presence of forage fish spawn, and changes in habitat characteristics such as sediment deposition.

Sampling occurs once a month, from late August through April, at a site with soft shore armorment and a site with a traditional bulkhead. Two transects are laid at each site encompassing the typical range of spawning habitat utilized by both surf smelt and sand lance. The surface sediment is collected along each transect and the samples are processed by sieving the contents to remove larger sediment while retaining egg-sized materials. The remaining mix of finer materials and any potential existing eggs are added to a vortex device which is designed to separate and lift materials lighter than the sediment. The lightweight material is collected and examined under a microscope to identify eggs, their species, and their development stage.