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First kokanee spawning at Nighthorse

Species was stocked four years ago

LAKE NIGHTHORSE – From a platform tethered 100 feet offshore, members of a Colorado Parks and Wildlife team spawned kokanee salmon in Lake Nighthorse for the first time.

Members of this first graduating class of kokanee were stocked as fingerlings in 2010. Stocking 75,000 kokanee each year since means spawning will occur annually.

They’re the only fish being taken from the lake, which is off limits to the public until a long-delayed recreation plan is in place. The lake also has stocked rainbow trout and voracious suckers.

The spawning Tuesday took place on the platform – catwalks above an enclosure imprisoning 1,500 to 2,000 agitated, swirling kokanee. A net extending from the platform to the shore forces kokanee into a maze that leads to the holding area. The average length of the salmon was 13 inches.

Parks and Wildlife aquatic biologist Jim White directed operations. Others were Pete Deren, a field technician; Mike Japhet, a retired biologist who once had White’s job; and volunteers Willy Reynolds, now in his seventh or eighth year at the job, and first-timers Chuck and Elizabeth Brannen.

Japhet dipped kokanee from the holding area into a tub of water into which carbon dioxide was pumped to stun them.

White and Deren then would each find a male and female kokanee and squeeze out the spawn (eggs) and milt (sperm) into a plastic cup where impregnation occurs within seconds.

The male kokanee is distinguished by a kype, a hooked jaw, more color and a slightly humped back.

White and Deren tossed the spent fish into a watery cage and passed the cup with the fertilized eggs to a volunteer. The volunteer rinsed the eggs and placed them in an iodine solution to be disinfected and to harden. The eggs can rupture if they’re moved before they harden.

Fertilized egg are transported to a Parks and Wildlife hatchery in Durango, where 90 percent of them will hatch, White said.

Kokanee, stripped of their means of reproduction, die within weeks. Before that happens, however, the Nighthorse kokanee will donated to the public.

Lake Nighthorse is one of 26 bodies of water in Colorado that are stocked with kokanee. The two closest reservoirs to Durango, where spawning already has occurred, are Vallecito and McPhee.

Wildlife officials hope to collect 13 million kokanee eggs annually for restocking.

Many of the captured kokanee here were still too green Tuesday to harvest spawn or milt. White and Deren determine if a female is ready by feeling her belly. A soft belly mean yes, a hard belly, no.

The Parks and Wildlife team will return here a couple of times a week to continue the operation. Since it was the first spawning here, it was hard to set a firm date, White said.

At Vallecito where spawning began in the 1960s and at McPhee where it began 15 years ago, he knows to the week when the kokanee will be ripe, White said.

When water was pumped from the Animas River to fill Lake Nighthorse, tiny suckers passed through screens meant to exclude them.

Now, White is looking for approval to stock the tiger muskie, a sterile northern pike/muskellunge hybrid that would eradicate the suckers.

The solution is way down the line, however, White said Tuesday.

daler@durangoherald.com



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