Those of you following steelhead passage over the dams have probably noticed that daily counts over Bonneville Dam are not picking up like we hoped they would. In fact, total steelhead counts over Bonneville Dam are currently about half the 10 year average. But that is only part of the story, as we are seeing some very strange things; and that is what I want to share with you today.
At this time of the year, the steelhead passing over Bonneville Dam are usually dominated by “A” run fish that are destined for places like the upper Salmon, Snake and Grande Ronde rivers. These steelhead are known to be the early arriving summer run fish and are usually dominated by fish that spend one year in the ocean. This year is looking quite different though. When we look at the PIT tagged fish passing over Bonneville Dam, what we are seeing is the vast majority of these steelhead have spent two years in the ocean. This seems to be the case for almost all stocks of steelhead migrating up the Columbia, hatchery and wild fish alike. To give you a feel for how unique this is, I am going to use steelhead returning to the Pahsimeroi Hatchery in the upper Salmon River drainage as an example. Returns to this hatchery are a good example of “A” run steelhead as they are dominated by early arriving 1-ocean fish.
The table below summarizes counts (based on PIT tags) of Pahsimeroi Hatchery steelhead that passed over Bonneville Dam since 2010. Since 2010, fish that spent two years in the ocean (2-ocean fish) have represented anywhere from about 8 to 33% of the run – that is until this year. As of yesterday (8/8/16), close to 90% of the of the Pahsimeroi Hatchery steelhead that have passed over Bonneville Dam have been 2-ocean fish. This is way out of the norm and has many of us scratching our heads. The good news is, it looks like more 2-ocean fish will return this year than expected. Those who have already been steelhead fishing have probably noticed how much bigger the fish are this year, which is great. The bad news is, the 1-ocean return is not looking good; and they usually make up the majority of the run for this time of year. Typically, by this time of the year, 33% of Pahsimeroi Hatchery returns have passed over Bonneville Dam. If this trend holds true, the total Pahsimeroi Return will be around 21,000 fish – not terrible, but the lowest return since we have had good PIT tag data. As I have indicated earlier, this trend isn’t unique to fish returning to Pahsimeroi Hatchery. We are seeing similar things for mid-Columbia, upper-Columbia, and Snake River stocks as well. This helps explain the lower steelhead returns we are seeing to date.
This information has many asking me “why is this happening." I can tell you that we were expecting a somewhat lower return of 1-ocean fish this year due to the low river flow conditions we experienced last spring and the poor ocean conditions that occurred when these smolts entered salt water. But, I wasn’t expecting it to be this low. The stronger 2-ocean return is a surprise to many of us. The 1-ocean return last year didn’t suggest this year’s 2-ocean return would be larger than average. It just goes to show you that we still have a lot to learn about these fish.
If you are wondering what the run of the Clearwater River “B” steelhead is looking like, it is really too early to tell. On average, by this time of year, less than 1% of the Clearwater River “B” steelhead will have passed over Bonneville Dam. We had an early surge of these fish pass over Bonneville Dam, but recently they have slowed down. So, I will withhold my judgment on the strength of this run until we learn more.
So, there you have it. This update probably leaves you with more questions than answers, but that is the way it is sometimes with steelhead. - Joe DuPont, Clearwater Region Fish Manager