Snohomish Estuary

The Tulalip Tribes along with its partners at the NOAA Northwest Fisheries Science Center, and Snohomish County Surface Water Management Department have been studying how juvenile salmon utilize the Snohomish estuary as they migrate from the spawning grounds up in the Skykomish and Snoqualmie Rivers out to the Puget Sound. The estuary provides important nursery habitat for many juvenile fish and is particularly important for juvenile Chinook who grow from a small fry, 1-2 inches, to smolts, 2-6 inches in length, in the estuary before they migrate out to the Puget Sound and eventually the Pacific Ocean. The purpose of the ongoing study in the Snohomish estuary is to better understand, when and where juvenile Chinook and other juvenile salmon species are present in the estuary, the water conditions the fish are living in, and the health of the fish. This information can then be used to help determine where further restoration efforts are needed (where are most of the fish and is there enough habitat for them?) help evaluate restoration projects (are there more and healthier in untouched areas vs restored areas vs areas that have been altered), and assess the overall health of juvenile salmon in the estuary.

The monitoring work involves using a small beach seine net deployed from a boat to catch juvenile and small fish at locations throughout the Snohomish Estuary. The fish captured in each net set are identified to species, their length is measured, and the number of each species is counted. At each sampling site water quality parameters and site observations are also recorded. Water quality parameters that are taken include water temperature, salinity, and the amount of oxygen dissolved in the water. The fish sampling starts in February and ends in late September with a fixed number of sites being sampled every other week during this time.

This allows us to look at how the number and timing of fish differs between locations within the estuary and across different years to see if there are any changes to the outmigration patterns of juvenile salmon and if restoration efforts are affecting the timing and use of different areas of estuary by juvenile salmon. The information collected from this monitoring effort helps to inform Chinook salmon recovery, estuary restoration projects, better understand the health and stressors of salmon population in the river and in the Puget Sound.