Idaho’s Steelhead fishery Update 

September 21, 2022

By Joe DuPont

Hi everybody. The steelhead migration over Bonneville Dam is well on its way, so I have a lot more information to share with you compared to my last update. I’ve got some exciting news and some not-so-exciting news. Read on, if this has piqued your interest.

Idaho’s Early Summer Run (Upper Salmon, Little Salmon and Snake Rivers)

During my last update on August 9 (steelhead update 8-9-22), I reported that about 26,000 steelhead destined for the upper Salmon and Snake rivers would pass over Bonneville Dam if their run timing was average. I also reported that 93% of the fish that had passed over Bonneville Dam had spent two years in the ocean which is very unusual (typically about 63% of these returns spend one year in the ocean). At that point, we were hopeful that the 1-ocean fish would eventually show up as they tend to migrate a little later than the 2-ocean fish. Fast forward to now (September 20, 2022), and it looks like the 1-ocean steelhead hardly showed up and has resulted in a smaller return than we were projecting. With the run now over 90% complete, we can confidently say that we will likely see 18,000 to 19,000 hatchery steelhead destined for the Snake and Salmon rivers pass over Bonneville Dam compared to the 26,000 we estimated earlier. That will make the return to these areas the fourth worst when compared to the previous 12 years.

To give you a feel for how this return of steelhead compares to the previous 12 years, I have put together the graph below. This graph compares the return of steelhead (using PIT tags detected at Bonneville Dam) destined for areas where we trap them for broodstock. The blue portion of the bars show the number of steelhead that spent one year in the ocean and the yellow portion shows how many spent two years in the ocean. If you look at the 2022 data, you will see that the number of 1-ocean steelhead we project will pass over Bonneville Dam this year will be the lowest we have seen since this dataset was started (since we started using PIT tags). Fortunately, the return of 2-ocean steelhead is fairly good. What this means is the return of steelhead to the Salmon and Snake rivers is going to be below average (similar to the last two years), but the steelhead will be larger than normal.

In the graph above, you will see text written vertically above some of the bars. This text indicates what the daily limits were in those years when we made restriction (daily limits typically are 3 fish) to ensure we collected enough broodstock for our hatcheries. If you look at this data set, you may wonder why we aren’t implementing more restrictive regulations this year. The answer is, we have learned from the past. In 2020 and 2021 when we saw similar sized returns, we ended up collecting an excess of broodstock. Plus, in years when most of the return is represented by 2-ocean fish, a higher percent of them are females and those larger females have more eggs than a 1-ocean female would. As such, we are confident that we don’t have to implement more restrictive fishing regulations this year to ensure we meet our hatcheries broodstock needs.

Idaho’s Late Summer Run (Clearwater River Basin Fish)

OK, now it is time for the exciting news! If you have been regularly checking fish counts at Bonneville Dam, steelhead counts have not been stellar which may have you thinking we are in store for another down return of steelhead to the Clearwater River basin. What is amazing though is that since late August about 66% of all the steelhead passing over Bonneville Dam are destined for the Clearwater River basin. Already, we estimate that about 29,000 hatchery steelhead have passed over Bonneville Dam that are destined for the Clearwater River basin. This exceeds the totals we have seen in the previous five years and around 30% of run hasn’t even passed Bonneville Dam yet. To give you a feel for how we think this year’s return will end up in comparison to the previous 12 years, I have put together the graph below. If this projection is accurate, only 2010 had a larger return when compared to the previous 12 years, and it would rank as the 7^th best hatchery return ever to the Clearwater River basin ever.

I do want to point out an interesting pattern we are seeing with Clearwater hatchery steelhead returns. Since 2012, the return numbers have been bouncing up and down and this has only got more pronounced in recent years (see graph above). Based on the low return of 1-ocean fish this year, it appears this pattern will continue with a down return next year. This pattern is often seen with Pink, Chum, and Sockeye salmon, and has been attributed to survival differences in the ocean. Because we release a consistent number of steelhead smolts from the Clearwater hatcheries, this pattern is also likely driven by factors happening in the ocean. We are starting to look into this to try and understand why it is happening.

Steelhead Fishing

Cold water releases from Dworshak Reservoir have been greatly reduced over the last week, and water temperatures in the Snake River have now dropped to around 67-69°F. What this means is that those Grande Ronde, upper Salmon, and Snake River steelhead that have been holding in the confluence area and Clearwater River are resuming their migration upstream. We have reports of salmon and steelhead being caught around Heller Bar and as far upstream as the lower Salmon River. Fishing should only improve in the Snake and Salmon rivers in the upcoming weeks.

For the Clearwater River, we are in a time period when out of basin steelhead are leaving and the Clearwater Hatchery fish are just starting to arrive. What this mean is steelhead catch rates likely won’t be that good for a week or two in the Clearwater River. However, with the large steelhead return that is coming, fishing could get quite good by early October. Early October could be a fun time to fish the Clearwater River as you will have the opportunity to harvest steelhead, fall Chinook Salmon, and Coho Salmon.

That is all I have for. I hope you all are enjoying your fall.

Take care everybody.