PINE, Idaho — The 2020 kokanee season in the Anderson Ranch Reservoir is bouncing back after several events in 2017 caused a ripple effect, taking a detrimental toll on the kokanee fish population in 2020.
Idaho Fish and Game (IDFG) said the 2020 kokanee season in Anderson Ranch Reservoir was the worst on record, with "dismal catch rates and poor overall fishing conditions."
The problem was a result of high levels of angler harvest on adult fish combined with heavy runoff in 2017 that flushed the young kokanee out of the Boise River system.
The factors together subsequently limited an entire generation of young kokanee in the fishery, coming to a head in 2020.
IDFG said that in 2020, there were no 3-year-old fish present in the reservoir for anglers to catch. However, biologists said the fishery has since continuously improved.
Sampling and data:
IDFG said the target kokanee catch rate at Anderson Ranch Reservoir is 0.5 fish per hour, with an average length of 12 inches.
Every summer, biologists conduct creel surveys analyzing angler catch rates, harvested fish sizes and overall angler satisfaction.
Additionally, IDFG distributes nets throughout the reservoir every fall when kokanee has matured and begun to explore surrounding tributaries, giving biologists a more comprehensive look at the relative abundance of upcoming kokanee year classes and the ability to forecast the fishery's upcoming years.
Fish and Game said data collected in 2022 and 2023 show that the 2024 kokanee season has yet again shown consistent improvement from the 2020 baseline. From 2021 to 2023, catch rates had doubled, and those 2023 rates were eight-times higher than the 2020 low.
Anglers are also harvesting smaller fish with an average length of 16.5" in 2023, from 17.5" in 2021. IDFG stated the decrease is important because "kokanee growth is density-dependent, meaning that when kokanee abundance is high, growth rates slow given limited food resources."
"Similarly, when kokanee density is low, they attain larger sizes due to less limitations for resources. abundance is increasing in Anderson Ranch Reservoir," IDFG went on to explain. "Most importantly, however, was the higher catch rates of age-0 and age-1 kokanee."
The department said the data indicates that natural reproduction is increasing in the system and biologists anticipate a fruitful 2024 fishing season.
Watch more Local News:
See the latest news from around the Treasure Valley and the Gem State in our YouTube playlist:
HERE ARE MORE WAYS TO GET NEWS FROM KTVB:
Download the KTVB News Mobile App
Apple iOS: Click here to download
Google Play: Click here to download
Watch news reports for FREE on YouTube: KTVB YouTube channel
Stream Live for FREE on ROKU: Add the channel from the ROKU store or by searching 'KTVB'.
Stream Live for FREE on FIRE TV: Search ‘KTVB’ and click ‘Get’ to download.