Kokanee still a mystery at Ririe Reservoir
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After a disastrous ice fishing season for kokanee last winter on Ririe Reservoir, fishermen were anxiously awaiting the gill netting operation done by the Department of Idaho Fish and Game, scheduled for last week. Tuesday evening, three nets were set in the lower portion of the reservoir and pulled on Wednesday morning.
“We normally catch about 65 kokanee per net per night, but this year we caught SUBSTANTIALLY LESS than that,” reported John Heckel, a regional fishery biologist, who oversees the gillnetting on the reservoir. “I don’t want to report the numbers until we have completed the survey, but we saw one fisherman catch one kokanee while we were on the water.”
Wednesday evening the Fish and Game personnel set the three nets in the middle section of the reservoir and the next morning the catch was “not good.” They spent the rest of the day running observations on the reservoir.
“We found that the lake had the same water temperature on the top as it was on the bottom and that zooplankton was in good numbers top to bottom,” commented Heckel. “The stratification that usually happens in early June had not occurred yet and the thermocline that usually forms in Ririe between 30 to 50 feet had not formed. Therefore, the area of the lake that usually holds the schools of kokanee where they are most active did not contain them and they appear to be scattered from the bottom to the top. Due to the record snowpack above the reservoir and the low temperatures of the record runoff, has put us a month behind where we should be.”
The wind and the wave action from boats mixes the water, which then creates stratification which creates the thermocline. When this happens, plankton becomes thick, causing the kokanee to school in that area, making them easier for fishermen to catch. Most fishermen are now noticing numbers of fish below 70 feet which makes kokanee tough to hook and harder to land. Most of the few kokanee being caught are large ones from 15 to 17 inches and probably two years old, near the end of their life cycle. According to Heckel, the ones caught in the gillnets represented three-age classes.
Another strange phenomenon happening this spring is the birds that normally feed on fish near the surface are few and far between on the lake. Wednesday while at the reservoir for three hours I observed only one Bald eagle and no ospreys or western grebes working the lake. Either there are few fish in the reservoir, or they are still too deep for the birds to harvest – hopefully they are still too deep and will soon move up in the water column and will become catchable.
“We will continue to monitor Ririe and will try to gillnet it when there is an indication that a thermocline has developed before we predict the numbers of kokanee,” said Heckel. “The water conditions are the best that we have seen in years and bode well for both perch and kokanee production. It looks like we will have to be a little patient before the fishing turns on as the water is still very high and cold.”
Both Heckel and Bob Johnstone recommend that the best fishing for all species is in the shallow south end of the reservoir near Blacktail. Fishermen are reporting limits of trout with a few kokanee mixed in. Schools of perch can be found on rocky, and mud shelves from 20 to 40 feet below the surface.
Looks like I will continue to chase rocks in Central Idaho for about a month before I get serious about chasing kokanee on Ririe. Be safe in your outdoor adventures and be kind to others while they are enjoying themselves and let’s hope Heckel finds his nets full when he can get back on the reservoir looking for them.