Spring Chinook Salmon Fishing Update 6/2/2020

Hi everybody, it is time for my weekly spring Chinook Salmon update (6/2/2020).

 

Run Size and Harvest Shares

The run of spring Chinook Salmon passing over Bonneville Dam that is destined for Idaho is pretty much done.  A few more spring Chinook will continue to trickle past Bonneville Dam, but right now we should be at the peak of summer run destined for places like the South Fork Salmon River and the upper Salmon River.  Unfortunately, Idaho’s summer run fish are coming in even weaker than our spring run fish.  To date (March 1 to June 1) the number of Chinook Salmon that have passed over Bonneville Dam is almost identical for what passed over last year for this same time period.  I will also mention that the passage of jack salmon destined for Idaho should be about 90% complete over Bonneville Dam.  This is the first indicator of what our adult return might look like next year.  Unfortunately, jack counts are the lowest we have seen (for the time period March 1 to June 1) since 2006.

counts_over_bonneville_dam_6-2-20
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Joe DuPont

Updates to the PIT tag data collected at Bonneville Dam are shown in the table below.  Harvest shares for the Rapid River return (lower Salmon and Little Salmon rivers) and Hells Canyon fisheries have increased some from last week and that is because these fish are surviving their journey better than we typically see.  Right now we are estimating that 83% of these salmon are successfully making their journey from Bonneville Dam to Lower Granite Dam.  On average, around 74% of the fish make this migration.  Because more of the fish are successfully making this migration, the harvest share for the Rapid River return is currently 617 adult Chinook and 197 adult salmon for the Hells Canyon fishery.  These are our “best” estimates of what the harvest share will end up being.  However, not until most of these fish have passed over Lower Granite Dam will the final harvest share be set.  Let’s hope upstream survival increases even more. 

harvest_share_table_6-2-20
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Joe DuPont

Rapid River Fishery

The combination of hot weather and monsoon like rainfall caused river flows to increase considerably more than forecasted last weekend.  By Sunday, the river was basically unfishable.  As such, we observed very little harvest.  We estimated that four fish were harvested in the lower Salmon River and two in the Little Salmon (see Table below).  That means all areas will reopen this coming weekend to fishing as we have over 500 fish left in our harvest share.  This week flows are supposed to steadily drop and then start increasing on Sunday due to anticipated rainfall.  That will likely mean this weekend will provide good fishing conditions.  However, we all know how forecasting the weather goes, it’s about as good as our forecasting of Chinook runs.  If rains come in earlier than anticipated, it could dirty up the water by the weekend. 

rapid_river_harvest_summary_6-2-20
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Joe DuPont

Right now some fish are having trouble finding their way past Little Goose Dam (the dam just downstream of Lower Granite Dam) which is causing fish to stack up there.  There are potentially around 3,000 adult Chinook Salmon below this dam based on counts at the next dam downstream (Lower Monumental).  Often, an adjustment in how flow passes this dam will correct this problem resulting in a surge of fish pushing upstream.  If this problem is fixed in the next day or two, that could create some good fishing in two weekends.  I’ll let you know next week what is happening with regards to this.

Finally, I need to let you know that there are several things we pay attention to as we manage the Rapid River run fishery.  First, we try to distribute harvest so that around half occurs in the Salmon River and half occurs in the Little Salmon River.  This is something most people approve of based on surveys we conducted this year.  We have a little over 200 more fish that can be harvested in the Salmon River before we reach that point.  We also pay attention to when upriver stocks of fish (such as the Pahsimeroi and SF Salmon returns) start entering the fishery.  When these runs are low, we don’t like to harvest many of these fish as it will only create bigger shortages in their broodstock needs.  Finally, we also are only allowed to kill a certain number of wild fish.  Currently, this does not seem to be an issue.  I am letting you know these things, because after this weekend, one of these management concerns could result in us closing down parts or all of the Salmon River. 

Hells Canyon Fishery

Catch rates improved last week below Hells Canyon Dam to around 47 hours a fish.  I would not call this good fishing, but it did result in more fish being harvested than in previous weeks.  Based on our creel surveys, we estimated 24 adult fish were harvested bringing the total for the year to 51 fish.  We are still well short of the harvest share which is currently at 197 fish.  That means this fishery will remain open for at least another week.  We started trapping broodstock at the Hells Canyon Dam yesterday.  We trapped 82 fish.  This trap will be operated every week until we meet broodstock needs (278 fish) and Tribal needs.

 

Take care everybody.