Sockeye migration reaches 100,000; cool temperatures delay Chinook, steelhead migration

May 12th, 2011

sockeye migration Our fish passage crew is working overtime trying to keep up with the large numbers of yearling sockeye smolts migrating into the new downstream fish capture facility at Round Butte Dam. These smolts are the offspring of the abundant kokanee population that Lake Billy Chinook has long been known for.

In spring 2010, about 50,000 sockeye smolts migrated downstream. This spring, we are seeing even more. On April 28, the fish passage crew had to recruit help from office staff to finish processing the more than 15,000 smolts that came into the facility—a new one-day record!

Sockeye migration count reaches 100,000
To date, about 100,000 sockeye smolts have been passed downstream this spring. Adults from the downstream migration in 2010 should return to the Deschutes in late summer 2012. Those leaving this spring should first arrive in late July 2013.

Kokanee, a landlocked salmon
Kokanee are a popular sport fish in the reservoir. In October, when they reach about 12 inches in length, they spawn in the Metolius River and tributaries. Kokanee, also called “landlocked salmon,” are actually sockeye salmon that do not move to the Pacific Ocean, but instead migrate between a lake and their spawning grounds in tributaries upstream. Like other Pacific salmon, they turn darker at spawning, and die soon after spawning. The young fry, about 1-inch long, emerge from their gravel nest the following spring and migrate immediately downstream to the lake to rear.

Anadromous (ocean-going) sockeye salmon historically spawned in upper Metolius Basin in Link Creek. Their young reared for a year in Suttle Lake before migrating down Lake Creek, and the Metolius, Deschutes and Columbia rivers to the ocean. They returned to Suttle Lake two years later as 4- to 8-pound adults to spawn in Link Creek and complete their life cycle.

The anadromous runs were pretty well gone from Suttle Lake before PGE constructed the Pelton Round Butte Project in the 1950s and 60s due to fish-passage barriers on Lake Creek. However, soon after Lake Billy Chinook filled behind Round Butte Dam in 1964, juvenile kokanee—the land-locked sockeye—naturally seeded the reservoir from Suttle Lake upstream. By 1968, kokanee were the most abundant salmonid in the reservoir, with annual spawning runs into the Metolius River with many spawning near Camp Sherman. Young fry migrated downstream into Lake Billy Chinook the following March and April.

With the construction of the new Selective Water Withdrawal and Fish Transfer Facilities at Round Butte Dam, many theorized that what we have been calling kokanee really were landlocked sockeye, and many would take advantage of the opportunity to safely migrate to the Ocean and reestablish an anadromous sockeye run into the Deschutes-Metolius system. The first part of that theory seems to be materializing.

Chinook and steelhead migration
Numbers of spring Chinook and steelhead smolts passed downstream are lagging behind the number captured by this date last year. However, tributary river temperatures are significantly cooler now than they were a year ago. We expect the migration of these two species to increase substantially when warm weather and associated warmer stream temperatures finally arrive.

- Don Ratliff, senior PGE biologist

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