Elwha Master Datafile - Elwha dam removal neashore monitoring

Removal of two dams on the Elwha River, Washington will help restore natural sediment processes to the coastal environment near the river mouth. We are interested in the responses of fish associated with shallow subtidal and intertidal habitats because they function as spawning and rearing habitat for many fish species including the ecologically important forage fish and federally protected species of Pacific salmon. Since 2006, we have been collecting species composition and size distribution of the intertidal/subtidal fish community in the Eastern and Central Strait of Juan de Fuca. Potential reference site and treatment sites (where sediment changes are expected to occur) were sampled on a monthly basis from April to September using a beach seine. We found over 45 species of fish, mostly juvenile stages, using this portion of the Strait of Juan de Fuca representing two groups- fish occurring in the water column and those living on or near the bottom. The water column species tended to be very abundant and included both migrants (e.g., juvenile salmon) and residents (surf smelt). Although the same species tended to be present each year, they often exhibited dramatic between year variability in abundance. This suggests the importance of using multiple years of data to evaluate changes resulting from dam removal. Treatment and reference areas exhibited some significant differences and we found seasonality in the fish assemblage structure. Our results suggest that some promising bio-indicators of short and long term change in sediment processes are: 1) numbers of species, 2) species diversity, 3) composition and sizes of benthic species, 4) abundance by life history stage of surf smelt, and 5) presence of migratory species like juvenile salmon. We will continue this work following dam removal to track the changes due to dam removal. For this project, the data was stored in .xls and access files.

[
  "https://www.fisheries.noaa.gov/inportserve/waf/noaa/nmfs/nwfsc/dmp/pdf/30856.pdf"
]