Photo: Robyn Rice
Kelp Monitoring

Kelp Monitoring


Bull kelp (Nereocystis leuktean) is the largest species of brown algae native to our region. This fast-growing seaweed can grow as much as 60 feet in length in a single year and is an important part of the rocky inter tidal ecosystem. It serves as both a primary producer in the food web of Puget Sound and as shelter and habitat for fish, invertebrates, marine mammals, and birds. In addition, the intricate structure of this living habitat buffers against current and wave energy, to help protect the nearshore ecosystem.

In the Puget Sound, there have been conspicuous declines in bull kelp abundance. While it is unclear what has caused these declines, potential factors include toxic pollutants from storm water, erosion, high sedimentation deposition, and overpopulation of kelp predators. 


In response to concerns over bull kelp decline and as part of our nearshore conservation goals, Snohomish County MRC seeks to understand how much kelp habitat is currently available in local waters.  Towards that end, all seven MRCs are continuing to gather data as part of the Northwest Straits Commission’s Regional Kelp monitoring project (2016) which contributes to an expanding regional story map and interactive Arc GIS database that tracks changes in number of kelp beds and total acres measured. MRC members recently completed our monitoring via kayak in early August 2018.



The MRC kayak surveys cover the entire southern portion of the Snohomish County Nearshore from the Snohomish/King county border to the Snohomish River Delta.  The MRC uses a standard protocol developed by The Northwest Straits Commission to simply and reliably monitor changes in existing kelp beds.

You can download detailed printable maps of kelp beds in EdmondsMeadowdale and Mukilteo.  Each map compares acres of kelp measured in 2015 through summer 2018. The Snohomish County MRC also provides an interactive map of current and historical kelp measurement data for regions where we currently monitor. 

Between 2015-2018, there has been a 77% decline in the area of kelp beds surveyed, and six of the nine beds originally found have disappeared. The MRC will continue to monitor kelp beds to better understand trends


Kelp Monitoring