VIEW FROM THE LADDER
What a CWF project in Yukon will tell us about the state of salmon spawning
Just outside Whitehorse is the world’s longest wooden fish ladder: 366 metres long and 15 metres high. It transports spawning chinook salmon past the Whitehorse hydroelectric plant. Here, amid the roar of the Yukon River, researchers with the Canadian Wildlife Federation are tagging fish, gathering data they hope will help solve the puzzle of the river’s declining chinook salmon run.
The Yukon River boasts the longest salmon run in the world. About 100 spawning grounds are spread along its various tributaries in the Canadian portion of the river alone. The chinook that journey farthest upriver after exiting the ocean must swim 3,200 kilometres against the current to reach their home streams.
Before 1997, an average 300,000 chinook entered the Yukon annually. In 2013, only 37,000 fish returned. As a result, in 2014, and again in 2015, fishing for chinook was banned entirely on both sides of the Alaska-yukon border, an unprecedented move. A modest rebound in 2016 and 2017 when 62,000 made it through to the spawning grounds has raised hopes, but some fishing restrictions still prevail.
In the past, 10,000 salmon were harvested annually upstream of Whitehorse, but in the past few decades only about 1,200 have been passing the dam. Fish continue from here to the spawning grounds and in some cases must still travel another 200 kilometres to reach their home streams. “We’re trying to fill in gaps in knowledge on either side of the ladder,” says senior CWF conservation biologist Nick Lapointe. “We are expecting that we will learn all of the places where chinook salmon spawn upstream of Whitehorse and what proportion of the population spawns where. We also hope to understand what proportion of the fish that approach the ladder pass it, how long this takes and whether delays at the ladder have any effect on migration success.”—
World’s longest wooden fish ladder bypasses the Whitehorse hydroelelectric plant Dams are one of the causes of the salmon crisis. Salmon need cool water to survive. Dams heat up the river by decreasing river flow and creating huge reservoirs that soak up the sun.