Port Susan Buoy

The Port Susan Remote Hydrolab Project supported operation and management of a remotely deployed water quality monitoring sensor, or hydrolab, along with a remote data transfer system, stationed on a buoy in Port Susan, the estuary through which juvenile salmon from the Stillaguamish River migrate.
The data collected from this project will be used to improve the information available on estuary conditions impacting Chinook survival by providing site-specific, hourly data for use in the stochastic Environmental Model to Predict Adult Returns (EMPAR) of Chinook salmon. This model is currently being used as an alternative forecasting tool for preseason estimates of anticipated escapements of ESA listed Stillaguamish Chinook populations. The model has shown a high level of correlation with estuary/nearshore conditions as major drivers in predicting future returns. The model substantiates existing research that first year environmental conditions strongly influence the overall survival of a given outmigration group.
The original remote data collection system deployed in 2011 had many issues that interrupted data collection. These included two moorage breakages in 2014 and frequent power failures in 2015 and 2016. To solve the first issue we replaced the original mooring prior to beginning this grant in January 2015. After numerous attempted to resolve repeated power and or communication failure issues, we decided to cease use of the remote data transfer system to reduce power failure potential. We also replaced and upgrade the water quality probe as it was five years old and had connectivity and software issues with our computers. In January 2017, using funds from a Pacific Salmon Treaty grant, we purchased a new multi-parameter probe, the EXO2, and deployed it into Port Susan Bay. This new probe records the same parameters plus turbidity, information valuable to research in Port Susan Bay due to high river sediment outflow. At that time we also deployed an independently powered GPS tracker that will contact the Tribe with the whereabouts of the buoy should it break free from its mooring. The new probe has been collecting data as expected.

The total number of valid data collection events during the duration of this grant is 11,617 hours. The events recorded data on average for eight parameters: temperature, salinity, conductivity, pH, dissolved oxygen, depth, chlorophyll, total dissolved solids, and/or turbidity. Several more years of data will need to be collected before being applied to the EMPAR model.

One of the largest challenges facing fisheries managers is accurately forecasting harvest levels in a manner that optimizes allowable harvest without impacting the recovery of critical at risk stocks. Stillaguamish North (summer) and South (fall) Chinook stocks are two of the most at risk populations within the Puget Sound ESU. Previous and existing traditional Beverton-Holt recruit and spawner modeling has not often accurately captured year-to-year variability of these populations. Using local data with high temporal resolution (hourly) in the EMPAR model will enable the Tribe to more accurately model the year to year survival variability and to have a better understanding of the relative importance of environmental factors on the survival of these populations will allow the managers to better manage fisheries and implement effective habitat recovery efforts.

Other benefits of this project include developing site specific baseline data that will allow us to document and monitor the impacts of phenomena affected by climate change, ocean acidification, and both freshwater and marine habitat improvements or declines. One example is such phenomena is changing water temperatures with spring freshets, and the consequent desynchronization of spring plankton blooms with outmigration timing, which can negatively impact juvenile salmon survival and population sustainability.