It is time for my weekly spring Chinook Salmon update (May 10, 2022). So, let’s get right to it and discuss what we have learned since my last update.
The day I sent out my last update (May 3), adult Chinook Salmon counts spiked at Bonneville Dam to 13,496 fish. We have not seen a daily count of over 10,000 fish since fish 2016, so this was great to see. To give you a feel for what I mean, take a look at the figure below. This figure compares this year’s daily Bonneville Dam counts of adult spring Chinook Salmon up through May 9 (red line) to last year’s return (solid black line) and the 10-year average (dotted black line). Unfortunately, since that big spike, daily counts plummeted back down with a couple of days of around 2,000 fish. Spikes of over 10,000 fish typically don’t last for more than two or three days. As such, this rapid drop was not too unexpected. However, the increase in flows at Bonneville Dam likely contributed to how far counts dropped. Outflow from Bonneville Dam stabilized on May 9 and the daily count increased to 3,530 fish. This brings the total count for adult spring Chinook Salmon at Bonneville Dam (March 15 to May 9) to 90,060 fish which is the best since 2016, and the fourth best when compared to the previous 10 years. The spring Chinook return over Bonneville Dam is probably around 70% complete, and we are now starting to see Idaho’s summer Chinook starting to show up.
So, let’s look at PIT tag detections at Bonneville Dam to better understand how many of the hatchery salmon passing over Bonneville Dam are destined for Idaho’s spring Chinook Salmon fisheries. I have updated the table below so that it now captures all the new spring Chinook Salmon data that has come in this past week. This table shows that the Clearwater River return’s harvest share is projected to be 5,112 fish (darker pink row), 3,920 for the Rapid River return (darker blue row), and zero for Hells Canyon (green row). These harvest shares are slightly below what I presented last week. If you look at the figure above, you will see that this year’s return looks a little early when compared to the 10-year average. The reason this is important is because the table below uses an average run timing to project how many fish will ultimately pass over Bonneville Dam. If the run is early, the harvest shares shown below will drop some, but I wouldn’t expect it to drop very much.
We still have not observed any harvest in Idaho in our creel surveys; however, we did receive a report of a fish being caught up by Orofino this weekend. I thought for sure more fish would have been caught this weekend in the lower Clearwater River. However, with all the rain the Clearwater basin received last week, flows increased from about 20,000 cfs to about 68,000 cfs in matter of three days. This increase in flow turned the Clearwater River into a dirty mess making fishing impractical. In addition, fish don’t like to migrate in those kinds of water conditions, so I suspect many of the fish passing over Lower Granite Dam just settled down in the reservoir and waited for the water to clear. Flows in the Clearwater have already dropped to 35,000 cfs, and the water is about fishable. With over 4,000 fish passing over Lower Granite Dam in the past 4 days, I expect a surge of fish to start pushing up the Clearwater River soon if not already. It is time to start fishing the lower Clearwater!
We trapped our first Chinook Salmon at Rapid River hatchery last week. So, for those of you who are itching to get out to fish the lower Salmon River or Little Salmon River, it won’t totally be in vain. However, I don’t expect the fish that passed over Lower Granite Dam this past weekend to reach the lower Salmon River for at least a week. Flows also picked up over the weekend in the Snake River which will slow down their migration some.
I mentioned last week that Lower Monumental Dam (second dam up from the mouth of the Snake River) was causing some delays in fish migration as four of its spill gates were taken out of service due to worn or damaged parts. To date, three of the gates have been fixed, and it seems that fish are now able to locate the fish ladder as over 10,000 fish have passed over this dam in the past three days. This wave of fish should be hitting Idaho in two to five days.
I hope you all had a good Mother’s Day weekend.