Aerial Surveys for Vessel Density

Healthy, flourishing eelgrass beds are vital to Puget Sound recovery but are in decline in the San Juan Islands. Eelgrass beds provide nursey, shelter, and food to ecologically, economically, and culturally important species and support a variety of ecosystem services including improved water quality, sediment stabilization, and carbon sequestration that help build coastal resilience to impacts of climate change. Boats are one of the current anthropogenic stressors to eelgrass due to physical disturbance and damage to eelgrass meadows, resulting in meadow fragmentation and accelerating decline in bed health and size. Despite high levels of boating in San Juan County (SJC), boater related impacts on eelgrass remain poorly measured here and elsewhere in Puget Sound. COVID travel restrictions of 2020 resulted in an increase in boating activity in SJC, raising the urgency of assessing boater impacts on eelgrass habitats and tribal treaty resources.

Boats in Blind Bay. Photo By Carl Davis

This project will be the first to determine areas of high boater impact on eelgrass and other habitats in the San Juan Islands. The objectives of this project are to:

(1) understand the nexus between boater presence and activity and eelgrass habitat health, and

(2) identify impact hotspots and prioritize sites for protection and/or restoration.

To achieve these objectives, systematic line-transect aerial surveys will be flown May through September 2024 to capture peak boating activities and densities in the islands. These data will allow a spatial comparison with existing mooring buoy and eelgrass data to identify impact hotspots. The expected outcomes include a spatial assessment of impact that can be used to inform future management goals and a prioritization of sites for protection and/or restoration. This project will provide a model strategy for implementation to advance efforts to enhance marine ecological and coastal resilience in the Puget Sound region.

Aerial Surveys: counting recreational boats from above.

Photos by Frances Robertson

Aerial Surveys for Vessel Density