Spring Chinook Salmon Fishing Update:
by Joe DuPont
The migration of Idaho-bound spring Chinook Salmon past Bonneville Dam continues to surprise me. Just when I thought the run was winding down we had another surge of 6,730 adult Chinook Salmon pass over Bonneville on May 11, and daily counts since my last updated have averaged about 4,000 fish (see figure below). This brings the total count for adult spring Chinook Salmon at Bonneville Dam (March 15 to May 16) to 118,022 fish which is the best since 2015, and the third best when compared to the past 10 years. The spring Chinook return over Bonneville Dam is probably around 85-90% complete, which means more and more of the run will be made up of summer run fish from here on out.
Last spring, ocean conditions were considered to be very good, and the jacks returning now are the first indicator of how these ocean conditions influenced salmon survival. As such, I want to share with you some information on the jack return especially since they are a good indicator of what the adult return will be like next year. The figure below shows this year's jack return (red line) in comparison to last year (black line), 2014 (grey line), and the 10-year average (dotted line). As you can see this year's jack return is shaping up to be better than last year and the 10-year average but less than we saw in 2014. The 2014 jack return was followed by the good adult return in 2015 that I discussed in a previous blog (May 3-22 update). It appears that the jack return is peaking right now which hopefully means we will see continued high numbers for another week. The good news is this jack return suggests that next year's adult spring Chinook Salmon return will be better than what we are seeing this year.
Last week, I indicated that the run timing looked a little early and not to be surprised if harvest shares dropped a little. Well, that surge of fish that passed over Bonneville Dam last week proved me wrong, and instead, harvest shares have increased from what I reported last week. If you look at the table below that uses PIT tag detections to estimate how many of the Chinook passing over Bonneville Dam are destined for Idaho's spring Chinook Salmon fisheries, you will see our harvest share estimates have increased since last week.
This table (available at original site) shows that the Clearwater River return's adult harvest share is projected to be 5,897 fish (darker pink row), 4,081 for the Rapid River return (blue row), and zero for Hells Canyon (green row). I don't expect harvest shares to change much because the run of spring Chinook Salmon over Bonneville Dam is probably over 85% complete. However, don't forget that we will evaluate how well PIT-tagged fish represent the actual return size based on genetics collected at Lower Granite Dam. As I indicated in a previous blog (April 27-22 update), the results from this analysis is usually completed by early June and could adjust the harvest share for the Rapid River return.
Clearwater River Basin Fishery
Finally, I have something to report about fish being harvested. To help capture how many and where adult Chinook Salmon are harvested, I will be including the table below in future reports. This table shows what we estimate the adult harvest share is (top cell highlighted in yellow), and how many fish we estimate were harvested each week in each creel river section (large area in yellow) within the Clearwater River basin. This table shows that the first three weeks of the fishery we estimated no fish were harvested, and then last week we estimated 458 fish were harvested. The vast majority of harvest (403 fish) occurred in creel river section 1 (Camas Prairie Railroad Bridge to Cherry Lane Bridge).
A key area to pay attention to in this table is the “total” row (just below the yellow area) that shows how many fish we estimate have been harvested to date and how much harvest share remains. Because harvest has just begun, we still have a lot of harvest share remaining (5,439 fish). The other area to pay close attention to is the section in blue. This shows how much of the harvest we try to allocate to the different river reaches and how much harvest remains before we will close that river section down. For example, we try to provide around 30% of the harvest in river section 1, and currently we have 1,366 adult fish remaining before we reach this goal.
If you pay attention to this information, it should give you a feel for how much longer certain river reaches will remain open. All indicators suggest that harvest will increase in all river reaches this week. Despite higher dirty water yesterday, we saw fish being harvested all the way up to Orofino. Water clarity is already improving, and I suspect fish will be harvested all the way up to Kooskia this week.
Rapid River Run Fishery
Last week we also observed the first Chinook harvested in the Rapid River run fishery. If you look in the table below, you will see that we estimated 19 fish were harvested last week, and all were caught in creel river sections 1-3 in the lower Salmon River. The table below is organized very similarly to the Clearwater Harvest Table I described above. I do want to bring your attention to the area in blue that shows in the Rapid River fishery we try to provide about 50% of the harvest in the lower Salmon River and 50% to the Little Salmon River. Although flows came up in the Snake and Salmon rivers, they are still below average for this time of year, and the fish should be moving up the river fairly quickly. Expect harvest and catch rates to only improve in the lower Salmon River this week, and it wouldn't surprise me if we saw a few fish harvested in the Little Salmon River.
Hells Canyon Fishery
Although we observed a few anglers fishing last week below Hells Canyon Dam, we did not observe any fish being harvested. This is not too surprising as few adults will be returning there this year, and the jack counts are just starting to pick up and Lower Granite Dam.
That is all I have for you until next week's update. I do what to give you a heads up that I will be in training next week, so next week's update will likely be short and to the point.
Good luck fishing.
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