South Fork & Henry's Fork Fishing Reports

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Jimmy's All Seasons Angler / Fishing Reports

Main Stem Snake River, March 2nd, 2021

Before flows increase, consider a trip to fish the Snake River below American Falls Dam where streamer presentation (cast and retrieve or drift under an indicator) is producing. Currently the reservoir is about 85 % full. The flow in the river below is somewhat under 400 cfs. This makes it easy to see all sub-surface features that can be dangerous to wading and it concentrates resident fish. However when irrigation begins in the Magic Valley, flows out of the dam will increase many times to satisfy water demands.  Now that we are in March, the increased flow could happen any time. We will keep track of how flows change here and give such information on this report to help you decide if a visit below the dam to fish is more or less an option.

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Small Streams ( Blackfoot River in particular), February 16th, 2021

Remember the  song “The Old Gray Mare, She Ain’t What She To Be?” Sadly, that title applies to fly fishing on the upper Blackfoot River.  Go back six to seven decades, and the run-up of Yellowstone cutthroat trout from the reservoir to spawn in and to inhabit the river was unbelievable in number and size of fish.  The fishing was phenomenal! But the accumulated effects of several happenings have reduced fishing in the upper river to a state that could be described as OK.  Mining, grazing, each a legitimate form of human activity, reservoir water management, creel rates being too liberal, and an influx of birds of preys all contributed to make the demise.  Nevertheless the river remains a major Yellowstone cutthroat trout stronghold. Fisheries managers, land owners, concerned fly fishers, and private individuals observed this decline and began an effort to bring back a good share of the river’s ability to host more cutthroat trout.  As a result an exemplary piece of cooperation from land owners, mining companies, agency folks, Trout Unlimited, Idaho Conservation League and other organizations are combining to turn things around.

Check out the video link below to observe what is going on and who is involved to bring back a good share of the mid twentieth century quality to the upper river and to show what people who care can combine to accomplish.  In this case it is to retain and improve the habitat for a unique part of the Rocky Mountain fauna, the Yellowstone cutthroat trout.

https://youtu.be/Q25o45_k9J0

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Henry’s Fork, February 9th, 2021

Are you interested in doing a trip to fish the upper Henry’s Fork and drainage during the upcoming season? Would seeing how snow and water conditions appear to be stacking up to help in planning? The information Dr. Rob VanKirk compiles may help. Rob’s analyses, and reports on water and snow conditions is as good as it gets.   Below is Rob’s latest update.

Henry’s Fork Water Supply, Feb 09 2021

Headlines:

  • After a dry day, water-year precipitation is 84% of average, and SWE is 85% of average.
  • Island Park Reservoir gained 112 ac-ft yesterday, typical of fill on recent dry days.
  • The reservoir is 87% full, compared with 75% full on average.
  • Weather forecasts continue to lean more toward wetter, warmer conditions and away from the extreme cold forecast last week.

Details:

At 6 degrees F below average, yesterday was the coldest in 13 days. Only a trace of precipitation was recorded, leaving the water-year total at 84% of average. Snow water equivalent (SWE) dropped a percentage point to 85% of average. After declining steadily since last July, the three-year average watershed precipitation appears to have bottomed out in the past two weeks and should increase a bit over the next few weeks, if precipitation forecasts prove to be accurate. This index of long-term watershed conditions is just a hair above average right now.

 

Forecasts are still uncertain about the details of weather over the next week but continue to gain confidence in warmer, wetter conditions than were forecast last week. Very cold air is expected to stay just on the other side of the Continental Divide, leaving us on the warm, wet side. “Warm” is relative, as temperatures are likely to be near average for the next week, a few degrees colder than last week. Regardless of temperature, snow is certain on Thursday and Friday and likely again early next week. The 7-day forecast calls for 0.25 inch across the lower elevations and up to 3 inches at the southern end of the Teton Range. As was the case last week, precipitation will favor the southeastern corner of the watershed. If forecast amounts materialize, SWE in Fall River and Teton River subwatersheds will improve to 90-92% of average by this time next week. SWE in the upper Henry’s Fork will remain at or below 80% of average.

 

Island Park Reservoir gained 112 ac-ft yesterday, typical of fill rate on dry days. The reservoir is 87% full, compared with 75% full on average. The reservoir will reach the April-1 target of 120,000 ac-ft around March 1.

 

Graphics:

  • Watershed three-year precipitation average
  • Island Park Reservoir inflow/outflow: 15-minute data
  • Island Park Reservoir volume: 15-minute data
  • Island Park Reservoir volume: predicted vs. observed

Three.year.precipIPInflow.15minIPVol.15minw.IPfill.obs

Station guide and disclaimer

Glossary of Terms

 

Rob Van Kirk, Ph.D.

Senior Scientist

Henry’s Fork Foundation

P.O. Box 550

Ashton, ID 83420

208-652-3567 OFFICE

208-881-3407 CELL

208-652-3568 FAX

 

[email protected]

Rob’s blog

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Main Stem Snake River, February 2nd, 2021

With flow coming out of American Falls Dam around 400 cfs and not much snow or ice around, now it is time to consider a trip to fish the river below. There is good access below the dam, and presenting streamer or leech patterns either by “cast and retrieve” or under an indicator is effective.  Experiment a bit to find the taking depth either way for the best success.

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Henry’s Fork, February 2nd, 2021

Midge hatches are beginning to appear on the lower river, but access can be a problem at many points.

Are you interested in doing a trip to fish the upper Henry’s Fork and drainage during the upcoming season? Would seeing how snow and water conditions appear to be stacking up to help in planning? The information Rob VanKirk compiles may help. Rob’s analyses, and reports on water and snow conditions is as good as it gets.   Below is Rob’s latest update.

Henry’s Fork Water Supply, Feb 02 2021

 

  • After a dry day, water-year total precipitation and SWE are both at 80% of average.
  • Island Park Reservoir gained 99 ac-ft yesterday, compared with 65 ac-ft/day needed to reach the target volume of 120,000 ac-ft by April 1.
  • The reservoir is 86% full, compared with 74% full on average.

Details:

Yesterday was warm and dry. Although the daily mean temperature was similar to that on Saturday, the afternoon high was the warmest since December 9. Water-year precipitation and snow water equivalent (SWE) are both at 80% of average. Precipitation is expected again tonight through Friday. The seven-day quantitative forecast calls for around 0.25 inch in the valleys, 0.5-0.75 inch in Island Park, and up to 2 inches in the Teton Range. Precipitation over the next week is expected to favor the southeastern corner of the watershed due to northwesterly flow.

 

The new monthly outlook issued yesterday gives better-than-even odds for above-average precipitation during the month of February, but one- and three-month outlooks have not performed well so far this winter. As mentioned yesterday, precipitation has been below average in three of the four months in this water year so far, long-range outlooks to the contrary.

 

Natural flow in the upper Henry’s Fork and Teton River continue to bounce around in the range of 90-95% of average. Contrary to my expectations, warm weather last week has not resulted in new streamflow data from ice-affected stations in the lower watershed.

 

Island Park Reservoir gained 99 ac-ft yesterday, compared with 65 ac-ft/day needed to reach the target volume of 120,000 ac-ft by April 1. The reservoir is 86% full, compared with 74% full on average. Reservoir volume is 116,143 ac-ft, 3,481 ac-ft ahead of my November-19 projection. If the seven-day precipitation forecast proves to be correct—and these short-range forecasts have performed well this winter—the reservoir will gain 310 ac-ft from direct precipitation and a total of around 1,000 ac-ft over the next week.

 

Graphics:

  • Watershed SWE
  • Island Park Reservoir inflow/outflow: 15-minute data
  • Island Park Reservoir volume: 15-minute data
  • Island Park Reservoir volume: predicted vs. observed

HFW.SWEIPInflow.15minIPVol.15minw.IPfill.obs

Station guide and disclaimer

Glossary of Terms

 

Rob Van Kirk, Ph.D.

Senior Scientist

Henry’s Fork Foundation

P.O. Box 550

Ashton, ID 83420

208-652-3567 OFFICE

208-881-3407 CELL

208-652-3568 FAX

 

[email protected]

Rob’s blog

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Henry’s Lake, January 23rd, 2021

Interest in the Henry’s Lake fishery status stretches far and wide. Jenn Vincent, IDF&G Upper Snake River Region’s fisheries biologist is charged with monitoring this status.  Here is Jenn’s summary report giving an analysis and tracking of the lake’s 2020 ice fishing, a comparison with past ice fishing seasons and thoughts on the fishery status going into and expected for the 2021 open water season.

Hitting the Hard Water at Henrys Lake

By: Jenn Vincent

Anglers spent a record number of hours fishing the hard deck at Henry’s Lake during the 2020 ice fishing season with over twice the total number of estimated fishing hours than the 2019 ice fishing season.  Despite this amount of angling effort, anglers harvested fewer trout during the 2020 ice fishing season than the 2019 season. Anglers harvested 22% of the trout they caught during the 2020 season and caught trout at a rate of 0.40 trout per hour.

Henry's Lake 1

Over the past year, COVID-19 has created many challenges for each and every one of us. One thing is for certain, this year has proven how important outdoor opportunities are in helping us all to step away and recharge even if just for a few hours. It was evident that many anglers took the opportunity to get away this winter and fish the hard water at Henry’s Lake.

Henry’s Lake is known internationally for its trophy-sized trout. Anglers have the chance at catching Yellowstone Cutthroat, Hybrid (Yellowstone Cutthroat x Rainbow Trout), and Brook trout on Henry’s Lake. Although the lake is a great place to visit throughout the year, ice fishing is a great opportunity for anyone to fish without the need of a boat or specialized gear. Anglers can fish with minimal equipment and can access the lake easily by foot or snow machine from various public access points around the lake. It’s a great opportunity for the whole family to get out and try their luck at some trophy-sized trout.

During the 2020 ice fishing season, which lasted from October 26 through midnight on January 1, 2021, we conducted a creel survey to estimate how many hours anglers fished, how many fish they caught, and how many fish were harvested on Henry’s Lake.

In order to collect the necessary information, we interviewed 154 anglers. Most of the anglers we interviewed (80%) were Idaho residents.

Anglers caught an estimated total of 27,756 trout over the season and harvested an estimated 6,175 of these fish. Anglers harvested 22% of the trout that they caught. Yellowstone Cutthroat Trout was the most commonly captured trout at 46% of the catch, followed by Hybrid Trout at 42%, and Brook Trout at 12%.

Anglers fished the hard water this past year for an estimated total of 69,144 hours over the entire ice fishery. This compares to 34,511 hours during the 2019 ice fishery (Table 1). The total number of trout caught and harvested this season is most closely comparable to the 2013 survey although the 2013 catch rate is three times higher than observed in 2020.

Table 1. Estimated total angler hours, total trout caught, total trout harvested, percentage of total trout harvested (%), and season catch rate (total number of trout caught/hour) for the 2013, 2016, 2018, 2019, and 2020 ice fishing seasons.

Year
2013 2016 2018 2019 2020
Tot. angler hours 21,833 9,354 34,556 34,511 64,144
Tot. trout caught 25,657 962 23,099 44,006 27,756
Tot. trout harvested 6,046 308 2,993 8,336 6,175
% trout harvested 23.6% 32.0% 13.0% 19.0% 22.2%
Catch rate (trout/hour) 1.18 0.10 0.67 1.28 0.40

Anglers caught an estimated 0.40 trout/hour through the ice which is less than the catch rate observed during the 2019 ice fishery which boasted a 1.28 trout/hour (Table 1). Our 2019-2024 Fisheries Management Plan for the state specifies that IDFG manages Henry’s Lake for a goal catch rate of 0.7 fish/hour. Henry’s Lake has had two consecutive good water quantity and quality years attributing to great water conditions, and fishing seasons have responded with good catch rates. We suspect the increase in angling pressure this year was related to recent good catch rates on the lake and impacts from the pandemic.

Henry's Lake 2

(Brrrr!)

When compared to the most recent open water fishery survey conducted in 2019, anglers harvested a similar proportion of fish they caught (Table 2). During the open water fishery in 2019, anglers harvested 14% of the fish they caught, while ice anglers during the 2020 season harvested 22%. The 6,175 fish harvested during the 2020 ice fishing season was just 25% of the fish harvested during the 2019 open water season, and harvest occurred at a higher rate during the open water season of 2019 (Table 2). Anglers during the 2019 open water season harvested one fish for every 7.1 hours of fishing effort while anglers during the 2020 ice fishing season harvested a trout for every 11.1 hours of fishing. Henry’s Lake anglers released most of the fish they caught during both years, and the number of fish harvested is lower than the number required to result in negative impacts to the population number or average fish size in the lake. The average length of harvested trout during the 2020 ice fishing season was 18 inches for both Brook Trout (BKT) and Yellowstone Cutthroat Trout (YCT), and 19 inches for Hybrid Trout (HYB) with the largest HYB measuring 24.6 inches in length. Harvested trout checked in by creel clerks this season were comparable to the trout checked in the 2019 open water fishery which averaged 16 inches for BKT and 18 inches for both YCT, and HYB. Last season we had a large age-2 class of trout in the population. These fish are likely still the trout being harvested in 2020 although they have had an additional year to grow following the 2019 open water fishery.

 

Table 2. Creel survey results including season length (day), total angler effort (hours), total trout caught, total trout harvested, and catch rate (trout per hour) for the 2019 open water fishery (May 25 through October 29, 2019) and 2020 ice fishery (October 26, 2020 through January 1, 2021) on Henry’s Lake.

2019 Open water Fishery 2020 Ice Fishery
May 25 – Oct. 29, 2019 Oct. 26, 2020 – Jan. 1, 2021
Season length (day) 158 67
Total angler effort (hour) 173,477 64,144
Total trout caught 183,484 27,756
Total trout harvested 24,773 6,175
Catch rate (trout/hour) 1.06 0.40

IDFG conducts a full season survey of anglers on Henry’s Lake every three years to better understand how the fishery is preforming. Our next season long survey will occur in 2022.

Henry's Lake 3

Overall, we estimated a two-fold increase in total angler fishing hours, a harvest rate lower than that observed during a recent open water season, slightly increased size in harvested trout due to increased overall sizes of trout in 2020, and a reduced total catch rate for the 2020 ice fishery on Henry’s Lake. Although the catch rate has decreased this season, Henry’s Lake still provides a unique opportunity for anglers regardless of season, gear type, and experience level to try their hand at pulling in a trophy-sized trout right here in Eastern Idaho.

 

 

 

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Henry’s Fork, January 19th, 2020

Many fly-fishers are interested in how winter’s progress will impact fishing quality in the Henry’s Fork and its drainage during the upcoming season. Dr. Rob Van Kirk, Henry’s Fork Foundation Senior Scientist, compiles and offers a water supply report sequentially throughout the year for the river and drainage. We at Jimmy’s believe that placing on our web site Rob’s presentation and analysis of data impacting Henry’s Fork water supply provides to a wider range of interested fly fishers more information with which to judge quality in its upcoming season. We therefore will provide Rob’s updates here during the winter season and into the irrigation season. The second of these is below.

Henry’s Fork Water Supply, Jan. 19, 2021

Headlines:

  • Continued dry weather has dropped water-year precipitation and SWE below 80% of average.
  • Over the past four days, Island Park Reservoir has gained 144 ac-ft/day; a fill rate of only 89 ac-ft per day is needed to reach the targeted capacity by April 1.
  • The reservoir is 84% full, compared with my projected value of 82% full and the long-term average of 73% full.

Details:

Weather over the past 10 days has been dry, with seasonable temperatures. Mean temperature last week was 1 degree F above average, and precipitation was around two-thirds of average for a mid-January week. Water-year precipitation to date is 79% of average this morning, and snow water equivalent (SWE) is 78% of average. Both indices have hovered around 80% of average for the past month. Snow accumulation will need to be 120% of average for the remainder of the winter just to reach average by early April.

 

The overall weather pattern over the western U.S. is expected to shift toward wetter conditions on Thursday. Areas of the drought-stricken Southwest will pick up the largest amounts of moisture. Over the next week, the Henry’s Fork watershed is expected to receive around 0.25 inch of precipitation in the valleys and around 1 inch in the Teton Range. Precipitation will favor the southern part of the watershed. Medium- and long-range outlooks continue to trend toward colder, wetter conditions for the entire western U.S., including our region.

Streamflow continues to be affected by cycles of river-ice formation and breakup. Natural streamflow yesterday was 92% of average in both upper Henry’s Fork and Teton River. The streamflow gage on Fall River at Chester has not reported accurate data since ice first formed in early December, but stream gages farther upstream show streamflow to be near average.

Island Park Reservoir fill continues to exceed both my predictions and the rate needed to reach the targeted content of 120,000 ac-ft by April 1. At an average outflow of 379 cfs, the reservoir has gained 144 ac-ft/day over the past four days, of which 28 ac-ft/day was due to direct precipitation on the reservoir surface. A fill rate of only 89 ac-ft/day is needed to reach 120,000 ac-ft by April 1. The reservoir is currently 84% full, compared with 73% full on average. By current USGS gage data, which is subject to change based on the next rating-curve adjustment, mean reservoir outflow since December 1 is 350 cfs, compared with 348 cfs on average. The Drought Management Planning Committee’s winter target outflow of 330 cfs is within streamflow measurement uncertainty around the nominal 350 cfs.

Graphics:

  • Weekly climate summary table
  • Weekly SWE summary table
  • Watershed SWE
  • Island Park Reservoir inflow/outflow: 15-minute data
  • Island Park Reservoir volume: 15-minute data
  • Island Park Reservoir volume: predicted vs. observed

Station guide and disclaimer

Glossary of Terms

Rob Van Kirk, Ph.D.

Senior Scientist

Henry’s Fork Foundation

P.O. Box 550

Ashton, ID 83420

208-652-3567 OFFICE

208-881-3407 CELL

 

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Henry’s Fork, January 5th, 2021

Many fly-fishers are interested in how winter’s progress will impact fishing quality in the Henry’s Fork and its drainage during the upcoming season. Dr. Rob Van Kirk, Henry’s Fork Foundation Senior Scientist, compiles and offers a water supply report sequentially throughout the year for the river and drainage. We at Jimmy’s believe that placing on our web site Rob’s presentation and analysis of data impacting Henry’s Fork water supply provides to a wider range of interested fly fishers more information with which to judge quality in its upcoming season. We therefore will provide Rob’s updates here during the winter season and into the irrigation season. The first of these is below.

Henry’s Fork water supply, Jan 05 2021

Headlines:

  • Another warm, wet day increased water-year precipitation to 82% of average and SWE to 85% of average.
  • At an outflow of 329 cfs, Island Park Reservoir gained 443 ac-ft yesterday, one-third of which was from direct precipitation on the reservoir surface.
  • The reservoir is 82% full and filling at well over twice the rate needed to reach the April-1 target.

Details:

Mean temperature yesterday was 10 degrees F above average, and precipitation was recorded at all stations except Alta. As predicted, precipitation heavily favored the upper Henry’s Fork for a change, where amounts through midnight ranged from 0.3 inch at Island Park to 0.7 inch at White Elephant and Black Bear. Ashton was again the winner in the valleys with 0.16 inch. Water-year total precipitation increased to 82% of average, and snow water equivalent (SWE) increased to 85% of average. Precipitation is continuing this morning, so storm totals will end up being quite a bit higher than reported through midnight. Only light precipitation is forecast for the next seven days, and the long-term outlooks call for generally dry conditions next week.

 

At an outflow of 329 cfs, Island Park Reservoir gained 443 ac-ft yesterday, one-third of which was from direct precipitation on the reservoir surface. The reservoir is 82% full, compared with 70% full on average. Fill rate has averaged 229 ac-ft/day since December 1, and a fill rate of only 103 ac-ft/day is needed for the rest of the winter to meet the April-1 target. Reservoir content is 1,880 ac-ft ahead of my November 19 prediction, which assumed an outflow of 330 cfs. As mentioned previously, higher-than-expected fill rate is due to a combination of slightly higher inflow and slightly lower outflow, at least according to our streamflow measurements earlier in December and to the power plant operator. According to USGS data, updated in mid-December, outflow since December 1 has averaged 344 cfs, compared with 341 cfs on average.

 

Graphics:

  • Watershed SWE
  • Island Park Reservoir inflow/outflow: 15-minute data
  • Island Park Reservoir volume: 15-minute data
  • Island Park Reservoir volume: predicted vs. observed

 

Station guide and disclaimer

Glossary of Terms

 

Rob Van Kirk, Ph.D.

Senior Scientist

Henry’s Fork Foundation

P.O. Box 550

Ashton, ID 83420

208-652-3567 OFFICE

208-881-3407 CELL

208-652-3568 FAX

 

[email protected]

Rob’s blog

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Main Stem Snake River, January 5th, 2021

Float fishing is a very popular activity on the Snake River, thus IDF&G strives to maintain boat launch facilities in good shape. Here are descriptions of recent repairs and improvements to the much used Menan Boat Launch Site by Darin Schneider Idaho Fish and Game.

Menan Boat Dock Repair

After spending time in the Big Lost drainage, the maintenance crew switched gears and worked on the Snake River’s Menan Access site where they made boat ramp repairs and replaced the dock. Prior to repairs, the boat ramp was too short at low water, with broken ramp tiles that needed replaced. The old dock was rough on boats, and was often too far away from the ramp to be useful or too far from the bank to allow one to step on the dock from the bank.

Big Lost River Campsite

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Darin Schneider Idaho Fish and Game

An additional 7 feet of boat ramp were added using concrete tiles to extend this ramp (pictured below), and replaced broken tiles in the upper part of the ramp (pictured above).

Boat Ramp

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Darin Schneider Idaho Fish and Game

The new tiles were connected together prior to installing them into the river and then used diving equipment to attach the new set of tiles to the existing ramp.

Menan Boat Dock

Creative Commons Licence
Darin Schneider Idaho Fish and Game

The repaired/extended boat ramp and the new dock in Menan are ready for use, but renovations are ongoing with plans for the installation of a gangway in 2021.

Menan Boat Dock

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Darin Schneider Idaho Fish and Game

The Upper Snake maintenance crew is always thinking outside of the box in an effort to provide the best public access sites possible in terms of usability and safety. “We enjoy what we do because we know how much the public values these access sites and the recreation activities these sites make possible,” says Recreational Site Maintenance Foreman Darin Schneider.  “I hope everyone is as happy as we are for what we have accomplished so far and stay tuned for more as we remain dedicated to continue maintaining and improving public access sites in the Upper Snake Region.”

Anglers are Reminded of Special Fishing Regulations on the Snake River Below American Falls Dam

Monday, December 28, 2020 – 3:49 PM MST

The tailrace fishery on the Snake River downstream of American Falls Dam to Eagle Rock has really grown in popularity over the past decade. This stretch of the Snake River has long produced a fabulous recreational fishery, one that has increased in both quality and diversity over recent history. Angler effort has followed suit, and for good reason—the fishing can be downright great throughout much of the year! The fishery is primarily supported by a combination of rainbow trout, brown trout, smallmouth bass, and white sturgeon. Anglers from near and far enjoy this stretch of river and it has become somewhat of a destination trout fishery.  This winter has been no exception, with recent angler effort being fairly high. Along with that, Fish and Game has documented an unusually high rate of non-compliance with the winter fishing regulations. In fact, Conservation Officers have detected several hundred angling-related violations over the past year along this stretch of river. The intention here is to provide some clarity and guidance that will help anglers stay in compliance with the special rules used to manage this fishery. Hopefully, this will break-down the regulation complexity and help make anglers feel at ease when they check-out this section of the Snake River.

Some fish populations in this portion of the Snake River are managed using special angling regulations, or exceptions to the general Southeast Region Rules found in the Idaho Fish and Game fishing proclamations. The Snake River is divided into two distinct reaches based on fishery management: 1) the section from American Falls Dam downstream to Eagle Rock, and 2) the section from Eagle Rock downstream to the western boundary of the Gifford Springs boating fishing zone. The special fishing regulations for these two river reaches are as follows:

Snake River

Section: From the downstream side of the Gifford Springs boat fishing zone (western boundary) upstream to Eagle Rock

• Bass limit is 2, any size

• Trout limit is 6, only 2 may be Cutthroat Trout

Section: From Eagle Rock upstream to American Falls Dam

• October 16 through Friday before Memorial Day weekend – limit is 0 for game fish species, catch-and-release, no bait allowed, barbless hooks required

• Saturday of Memorial Day weekend through October 15 – bass limit is 2, any size; trout limit is 6, only 2 may be Cutthroat Trout, only 2 trout over 16 inches

With respect to the section from Eagle Rock to American Falls Dam, no harvest of game fish species is allowed between October 16th and the Friday before Memorial Day (that’s May 28th in 2021). In addition, anglers are not allowed to use bait and must use barbless hooks during this period. Bait and barbed hooks are allowed starting the Saturday before Memorial Day; however, the regulations still differ from the general fishing regulations. During this time, the daily bag limit for bass is two (both species combined) and the trout daily bag limit is six. Only two of a six trout daily bag may be cutthroat trout, and only two trout of any species may be longer than 16 inches.

From Eagle Rock downstream to the Gifford Springs area, the bass limit is two and trout limit is six. Again, only two of any trout in a six limit daily bag may be cutthroat trout. Any size trout may be harvested in this reach.

The intent of special angling regulations is to control angler interactions in a way that supports management direction and provides specific angling experiences. Special rules are an important tool that fishery managers use throughout the state to shape fisheries and angling experiences congruent with the state’s Fisheries Management Plan. Remember, nongame fish species may be harvested by any legal method at any time during the year.

Anglers are encouraged to contact the Southeast Regional office or try out IDFG’s fishing planner (https://idfg.idaho.gov/ifwis/fishingplanner/) for additional guidance and regulation-related information. For more about how to interpret and use the IDFG fishing proclamations, check out this video resource (https://www.youtube.com/watch?v=5ZUbcBfalaM&feature=youtu.be).

  • img_2434

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    D Teuscher
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South Fork, January 2nd, 2021

It looks like about 900 cfs will be the maintenance flow out of Palisades Dam until the upcoming irrigation season. That seems a bit small to some folks, but consider that tributaries add a considerable amount of water to the river on downstream at least to Heise where the flow increases to around 1300 cfs.

In any case, the South Fork is arguably our most popular river for angling. That being said, IDF&G spends a good deal of its fishing resource allocations on studying and maintaining its salmonid population. Below are results of recent studies that indicate good news for the salmonid population, the wildlife that depends on it, and anglers.

 

High trout numbers continue in the South Fork Snake River

By Pat Kennedy

The South Fork Snake River (SFSR) in eastern Idaho supports the largest river population of native Yellowstone cutthroat trout in Idaho as well as other popular game fish including Rainbow trout and Brown trout. Idaho anglers have repeatedly asked Fish and Game managers to focus management efforts on protecting native trout species when possible. This public sentiment is reflected in our state fish management plan where the goals for the South Fork Snake River include: protecting the genetic integrity and population viability of cutthroat, and reducing rainbow trout abundance to less than 10% of the trout in the upper river near Conant, as was the case in the mid-1980’s. These goals are also reflected by the Yellowstone cutthroat trout management plan. Each fall, IDFG employees use boat electrofishing techniques to estimate trout numbers in order to gauge management efforts relative to goals stated in the management plan. Results from 2020 surveys suggest two things; trout numbers are at a record high and Rainbow trout still comprise more of the population in the upper South Fork than called for in the management plan.

yct

Almost every year since 1986 IDFG conducted abundance estimates in October near the Conant boat ramp to monitor trout abundance in the upper river. At our Conant monitoring reach, we estimated trout densities to be 6,302 fish/mile. The 10-year average is 4,710. Good trout numbers are expected to contribute to continued good catch rates for anglers. Rainbow trout, which are the biggest threat to cutthroat trout through competition and hybridization, continue to provide management challenges. Rainbow trout made up 43.1% of the trout catch, so IDFG plans to continue efforts to lower their abundance using the angler incentive program and other tactics.

sf_boat

Pat Kennedy, IDF&G

Figure 1.               Estimates of fish per mile for Yellowstone cutthroat trout (YCT), rainbow trout (including hybrids; RBT), and Brown Trout (BNT) at the Conant monitoring reach from 1982 through 2020 with 95% confidence intervals.

Figure 1

Abundance surveys have been conducted near the Lorenzo boat ramp most years since 1987 to monitor abundances in the lower river.  At Lorenzo, Yellowstone cutthroat were estimated at 1,260 fish/mile, the highest on record (Figure 2)! The ten-year average for cutthroat is 407 fish/mile. The total trout estimate was 2,650 trout/mile which was significantly higher than the ten-year average of 1,889 trout/mile. Brown trout are doing well here too with 1,390 fish/mile which is slightly lower than the ten-year average (1,477 fish/mile).

f2

Figure 2.              Estimates of fish per mile for Yellowstone cutthroat trout (YCT) and brown trout (BNT) at the Lorenzo monitoring reach of the South Fork Snake River from 1987 through 2020 with 95% confidence intervals.

Electrofishing boat

Pat Kennedy, IDF&G

The most important take-home message from these surveys is that trout abundance is high in the SFSR. The total trout estimate is higher than ever estimated at Conant, since 1982. Cutthroat appear to be doing fairly well, despite the continued threats from rainbow trout. Unfortunately, what’s good for one species seems to be good for the other, as rainbow trout continue to comprise a greater proportion of the population.

 

Other rivers in the western U.S. also host estimates of trout per mile in the thousands, but few boast estimates higher than 5,000 trout/mi. Within Idaho, the South Fork Boise, Big Lost, and Henry’s Fork rivers boast some of our highest abundance estimates, but none have exceeded 6,000 fish/mi. Other rivers in the west such as the Green River below Flaming Gorge reports 10,000 trout/mi, but stocked 14,500 RBT in the summer of 2020. Similarly, the Idaho rivers with high abundance typically receive at least some hatchery trout supplementation. The SFSR is not supplemented with hatchery trout. The exceptional wild trout population in the South Fork highlights the extremely high productivity observed in recent years in the river and the potential this tailwater fishery possesses. For anglers, high abundances of trout should ensure that fishing will remain great into next year and beyond.

 

 

 

 

 

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