In case you were wondering, there are more than 7,000 rainbow trout, not to mention 26 pink salmon, 215 bull trout, and 539 adult Chinook salmon in the Elwha River in Olympic National Park. Park officials know that because a team of snorkel-spouting biologists swam the river's 42 miles specifically to count the fish.
The fish survey, conducted August 20-24, was done in preparation of the removal of the Elwha and Glines Canyon dams so biologists would have baseline fish populations. According to the United States Geological Survey:
The Elwha River was once one of the most productive salmon streams in the Pacific Northwest, home to all five species of Pacific salmon, as well as other fish species. The Elwha and Glines Canyon dams have blocked fish from all but the lowest five miles of the river since the early 1900s. Removal of the two dams will restore the Elwha to its natural, free-flowing state and will once again allow fish access to over 70 river miles of habitat now protected within Olympic National Park. Dam removal will begin after water quality protection facilities are complete.
A team of 21 biologists from the National Park Service, the U.S. Fish and Wildlife Service, the U.S. Geological Survey, the Lower Elwha Klallam Tribe, the National Oceanic and Atmospheric Administration, Peninsula College, and the Wild Salmon Center took part in the survey. The divers started at the river's headwaters just above Chicago Camp and ended where the river flows into the Strait of Juan de Fuca west of Port Angeles.
"As we continue to move closer to removing the two Elwha River dams, it's vitally important that we have an understanding of the ecosystem as it is today," says Olympic Superintendent Bill Laitner. "Establishing a baseline of fish populations before dam removal will help us better understand and measure the success of dam removal and (river) restoration."
The counting was done by teams of two snorkelers who moved downstream together at the speed of the current. They kept track of the fish they counted on dive slates attached to their arms. The information will help biologists track salmon recolonization of the Elwha once the dams are gone.
The greatest fish densities were recorded in the five river miles below the dams, where divers counted Chinook, pink and Coho salmon as well as sculpin, bull trout, threespine sticklebacks, starry flounder, and freshwater mussels. Above the dams, the only species seen were rainbow trout and bull trout.
"Perhaps the most riveting aspect of the headwaters-to-ocean survey was the reality that Pacific salmonids will be rewarded with exceptionally high quality spawning gravels in remote sections of Olympic National Park following dam removal," says Sam Brenkman, the park's fisheries biologist.