Spring Chinook Salmon
by Idaho Fish & Game
Rapid River Run, Hells Canyon, and Clearwater River Fisheries
Hi everybody. Now that the Rapid River Run fishery is closed and the open fisheries are not at risk of closing in the near future, this will be my last spring Chinook Salmon update (6/30/2021). If the Hells Canyon or Clearwater River fisheries close before August 8, I will send out an alert to let everybody know.
One of my traditions for my last update is to provide a rough forecast for next year's adult returns based on the number of jacks that returned this year. So be sure to read this entire update if you are interested in this.
The run estimates and harvest shares for each of the spring Chinook Salmon fisheries are listed below.
Rapid River Return
The entire Rapid River return fishery closed at the end of fishing hours on June 18. As such, there is nothing new to report for this week.
This is the third week in a row that we did not observe any Chinook Salmon being harvested below Hells Canyon Dam. We estimate that 90 adult fish were harvested from this fishery this year. Although I don’t expect any more fish to be harvested from this fishery this year, it will likely remain open until the end of fishing hours on August 8, 2021. If anything changes between now and then, we will sent out an alert.
Clearwater River Return
Last week was the fourth week in a row where catch rates for Chinook Salmon averaged 2 hrs/fish or better in the North Fork. I have never seen such high catch rates for this long of period. Outside of the North Fork, we aren’t seeing much effort. Right now we are about 66% of our way to our adult harvest share (through catch-and-release mortality), and 42% of the way to our jack harvest share (see tables below). Because we have a long way to go before we reach either of our harvest shares, this fishery will continue to remain open four days a week (Thursday through Sunday) until the end of fishing hours on August 8, 2021. If anything changes between now and then, we will sent out an alert.
FORECAST FOR NEXT YEAR
As I indicated earlier, one of my traditions for my last Weekly Chinook Salmon update is to provide a rough forecast for next year’s adult spring Chinook Salmon returns based on the number of jacks that returned this year. You need to be aware that method I am using is based on PIT tag run estimates which are not as accurate as the “official” forecasts we will put out at the end of the year that utilize genetic data collected from fish trapped at Lower Granite Dam.
The premise behind this forecasts is there is a relationship between the number of jacks that return one year and the number of adults that will return the following year. The more jacks that return, the more adults we can expect to return the following years. The two figures below show the number of adults (yellow bars) and jacks (red bars) that have passed over Lower Granite Dam that are destined for the Clearwater basin and Rapid River since 2009. If you look at these graphs, you will notice that on years we had large jack returns, the following year the adult return tended to be big. On the other hand, when the jack return was small, we tended to see small adult returns the following year.
I created the table below that matches up one year’s jack return with the following year’s adult return so you can better view this jack to adult relationship. As you can see, there is a lot of variability in this relationship, but there is some correlation. At the bottom of this table, you will see the two cells in yellow. These are next year’s forecasted adult returns for the Clearwater basin and Rapid River based on the average relation between jack and adult returns. Both forecasts are better than we have observed the previous five years, which gives me hope that we all will be able to experience better spring Chinook Salmon fisheries next year.
So that is it for my spring Chinook Salmon updates this year. As a reminder, if you want updates on the South Fork Salmon River summer Chinook Salmon fishery, I would suggest asking Jordan Messner to get on his e-mail list (email@example.com). He provided this update yesterday if you have not seen it (South Fork Salmon Update).
I’ve already been getting people asking about this year’s steelhead and fall Chinook Salmon returns. I will probably hold off until August before I provide updates on these fisheries. At this point, there is a lot of uncertainty about how these fisheries will turn out, so I will wait to provide an update until I can give you something more accurate.
I hope you all have a great summer.
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