Spring Chinook Salmon Fishery Update (5/18/2021)

Rapid River Run, Hells Canyon, and Clearwater River Fisheries

Hi everybody, it is time for my weekly spring Chinook Salmon update (5/18/2020). Here is what I have to report.

 

Run Update

As of yesterday (May 17, 2021), 54,078 adult Chinook Salmon had passed over Bonneville Dam this spring season which is about 54% of the 10-year average. During my last update (5/11/21), we were at about 45% of the 10-year average. This increase can be explained by a short spike where daily counts at Bonneville Dam exceeded 3,000 fish for a couple days (see the red line in the figure below). This peak was desperately needed (and a pleasant surprise) to maintain the fisheries we have. As you may recall, last week we were worried the run was a little early and our harvest shares would continue to drop.

To better understand how this spike in counts at Bonneville Dam influenced our forecasts for Idaho’s fisheries, let’s look at the PIT tag detections which are summarized in the table below. What the PIT tag data shows is that potential harvest shares (fourth column) have gone up for all three spring Chinook Salmon fisheries in Idaho from what we estimated last week. We now estimate the Rapid River run harvest share will be at over 1,000 fish, the Hells Canyon fishery around 170 fish, and the Clearwater River run is now at 295 fish. Our harvest share estimates for the Clearwater River run has been bouncing around so much we aren’t quite ready to decide if we can open the season there or not. As such, we would like to hold off one more week before we make a decision. By next week, we expect around 95% of the Clearwater River run to have passed over Bonneville Dam, which should allow us to make a decision with high confidence on what kind of opportunity we can provide.

On a positive note, jack counts have picked up at Bonneville Dam, and it looks like they will exceed what we have counted the previous three or four years. I wouldn’t consider this to be a strong jack return, but it is good to see some improvements over previous years.

 

Fisheries

As suspected, we documented harvest in both of our open fisheries (Rapid River and Hells Canyon) this past week. Now that harvest is occurring, I will start including a table (see below) that shows how many and where adult Chinook Salmon are being caught from the Rapid River run fishery. Last week we estimated that 154 fish were harvested in this fishery and all were caught in the lower Salmon River (none from the Little Salmon River). About 77% of the harvest occurred in the lowest section between Rice Creek Bridge and Hammer Creek Boat Ramp. Catch rates ranged from of high of 15 hours/fish below Hammer Creek to a low of 56 hours/fish between Hammer Creek and Time Zone Bridge. We don’t see catch rates better than 15 hours/fish very often in smaller returns like is occur this year. As a reminder, we try to split the harvest evenly between the lower Salmon River and Little Salmon River. That means we have about 380 fish to go (assuming the harvest share doesn’t change) before we shut down the lower Salmon River. It is not unthinkable that close to 380 fish will be harvested this week in the lower Salmon River which means if you really want to fish the lower Salmon River, you better go this week. There is no guarantee that it will be open another week. 

We also estimated that four adult Chinook Salmon were caught below Hells Canyon Dam last week. That leaves 165 fish before this harvest share is met. Catch rates were about 56 hours/fish which is not good, but this fishery should improve over the next two weekends. We plan to start trapping broodstock on June 1, and once we open the trap below Hells Canyon Dam, many of the fish leave the fishery which will cause catch rates to decline.

 

That is all I have for you until next week’s update. Good luck fishing!