Tahoe Kokanee

[Tracy Chimenti]

I had to add my own retort... Surprise Dr. Ralph didn't tell the story.

I can remember boating on Tahoe in the 60's and 70's in our sail boat and the kokanee wer huge-- 4-pounders. The lake held the state record for many years and likely still does.

The agency felt that improving on this resource was possible by introducing mysis shrimp, which were quite larger that the daphnia, the traditional zoo plankton prey of the kokanee. The problem arose when the mysis fed on the other zoo plankton in the ologotrophic body of water at night, and then sounded to 200-feet during the day. The kokes never got to increase their portion size and were roundly denied the amount of daphnia they fed upon in earlier times. The result was smaller kokanee and food for juvenile mackinaw since the opossum shrimp were multiplying in the depths. This is one reason why a 4-pound mack might as well be made into emulsion to make sweet cherries. They taste yucky due in part to their diet. If that wasn't enough, DFG, local fishery activists, and even trout advocacy groups lobbied to reduce the limit on the macks from five- to two-fish. So now we have an over-abundance of slow-growing juvenile macks and very little harvest of them.

In Flaming Gorge, where huge brown trout and rainbows were a staple of the 60's and 70's, either Wyoming or Utah released kokanee to add another angling demension. In the end, the kokes gill-raked the zoo-plankton, the preferred food of small chubs, which were the stepping-stool forage for the browns and rainbows in their juvenile state. The result? Brown and rainbow trout growth rates were cut in half and and old fish was lucky to get to 14-pounds.

I am still amazed at what a fish factory Stampede is though. Still produces hawg browns and rainbows, even thought the kokes have bottomed out. Not as many, but they do still get freighteningly big.

[OceanSunfish]

Thanks Tracy for the insight.

My first visit to Taylor Creek was around 1975 and 3 to 4 pound Kokanee sounds about right based on what I saw......

With regards to the introduction Mysis Shrimp..... ugh. I assume Daphnia were native to Tahoe?

[Ralph]

Turn of the century photos of stringers of huge Tahoe cutthroat show how perfect an ecosystem can be without being "managed". I'm trying really hard to think of a species introduction into Tahoe that didn't make things worse than before the introduction.

[Nick B]

Tracy nailed down why the kokes are smaller... Mysis relicta were introduced into the lake in the late 1960's and hammered the zooplankton communities (namely Daphinia, which were native), leaving a mysid/copepod dominated system, that is ill-suited to koke growth. The state record was actually pulled out of Tahoe prior to this introduction (~5lbs).

The massive LCTs of the Tahoe/Pyramid system were wiped out by many of these introductions as welll as a commercial fishery for them, which operated during the turn of the century.

If anyone wants to read more about the historical ecosystem of Lake Tahoe, there is a good paper out by Zander, Allen, Chandra, Reuter and Goldman (2003) which talks about it at legnth.