Idaho kokanee - interactive story

[IDFG_Fisheries]

Hi there folks,
This is the time of year that kokanee may be swimming to a stream near you. To celebrate the run, here's a new interactive 'story map' about the complex process of helping to manage kokanee populations across the state. Click on the link and then just start scrolling down through the pages.

https://arcg.is/1yrOuO

Enjoy,
Martin Koenig
Sportfishing Progam Coordinator
Idaho Dept. Fish and Game
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[MMDon]

Thanks Martin! That was well done and very informative!
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[Bmarsh]

Pretty Cool process, caught it on Crackbook when it was shared there.
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[fallsfish]

Well done. I've got a question about growth rate and size of Kokanee at three years. Why are the Kokanee in Ririe only 14 inches or less at the three year stage? I've especially noticed this after the stocking number went from around 200K to 300K.

I understand the Kokanee in Flaming Gorge live an extra year and grow to the 20-22 inch size. Are they a different line of fish?
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[MMDon]

Basically Kokanee are Kokanee. The Maturation Timeline really depends on an abundancy of food in the biomass. With the huge amount of nutrients and minerals that wash into Flaming Gorge via the Green River, the Kokanee feel no threat of a food shortage and many but not all simply put off going into spawning mode at 3 years. We see the same pattern in years of abundance of food in the Pacific Ocean and King Salmon not returning to spawn until the 4th year.

I should have noted that we do see some 4 year Kokanee that naturally spawn in Palies as well.
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[IDFG_Fisheries]

Great question!

As others have mentioned, kokanee size at adulthood mostly depends on two major things:

1. Lake productivity (how much food/plankton the lake can make). Of course, this can change from year-to-year depending on runoff, drought, etc. Biologists don't have much control over this part.

2. Numbers of kokanee (more kokanee = smaller size). This depends on stocking AND natural reproduction from any spawners (also hard to control... think Deadwood weir that controls spawning numbers).

Kokanee all eat the same thing: plankton. So, when there are more kokanee, there is less food to go around, and they reach adulthood at smaller sizes. Yes, there is some differences in age/genetics etc., but that usually isn't the driving factor of ultimate size.

Stocking kokanee is a tricky business! The idea is to get the best combination of size and catch rates. Lakes like with huge kokanee usually don't have very many of them, so while you might catch some big ones, you probably won't catch very many.

Stocking at Ririe got a big increase in 2013, then back a little in 2014 to around 300K a year fairly consistent. The intention is to dial in the right stocking numbers to get that good combination of average size with good catch rates.

IDFG is still evaluating the Ririe kokanee fishery to see how the stocking numbers are working. If you have more questions, Dan Garren in the Idaho Falls office would be happy to talk about it. He'll have the details on how the lake is managed.
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[muddyrudder]

Awesome and informative,

Thank you
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