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Here are links to file photos of Hofer Rainbow trout. Simple copy and paste. Also below is photo caption information. Please, credit photos to Colorado Division of Wildlife.

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This is a cross between a Hofer rainbow trout and a strain of rainbow that the DOW has used for many years. The Hofer cross rainbows grow more quickly than the traditional rainbows. This fish, hatchery raised for brood stock, is about 18 months old.

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George Schisler is an aquatic researcher for the Colorado Division of Wildlife and has been doing whirling disease research since the mid 1990s. He’s holding a Hofer cross rainbow trout that is about 18 months old. This fish was raised in a hatchery. But in the wild Hofer cross rainbows grow more quickly than traditional rainbow strains.

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These are hatchery raised rainbow trout that are 8 months old. On the right are Hofer rainbows that are about 8 inches long; the other fish are traditional rainbow strains. The Hofer rainbows grow faster in the hatchery and in the wild than traditional rainbow strains.

For more information about Division of Wildlife go to: http://wildlife.state.co.us.

CONT.
DOW SEES NEW STRAIN OF WHIRLING-DISEASE RESISTANT RAINBOW TROUT HATCH IN WILD

For the first time since whirling disease decimated most naturally reproducing rainbow trout populations throughout Colorado more than a decade ago, new strains of rainbows have reproduced naturally in the Gunnison River and in ponds located along the Frying Pan River near Basalt.

Colorado Division of Wildlife biologists are hopeful that the successful natural reproduction will lead to re-establishing wild, self-sustaining rainbow trout populations in Colorado where whirling disease has precluded wild rainbow trout recovery efforts. The fish, a cross of the Hofer rainbow trout and other rainbow strains that are used for stocking, appear to be resistant to whirling disease.

The fish were “young of the year”, and hatched in May 2007. They were captured in October when DOW aquatic researchers conducted electro-fishing operations in the two areas.

“They were plump, colorful fish, they looked good,” said Barry Nehring, an aquatic researcher for the DOW in Montrose who has been working on whirling disease since 1994. “This is indicative that we’ve had successful reproduction.”

Several of the fish were then sent for genetic testing to a laboratory in Boulder that verified the fish were offspring of Hofer-cross rainbows stocked in the river and the ponds in 2004 and 2005.

Hofer cross fingerlings were also stocked in the upper Colorado River near Kremmling in 2006 but researchers did not find any young fish there in 2007. Biologists said that fish grow more slowly in the Colorado River because the water is very cold. Consequently, researchers speculate that Hofer crosses stocked there might not yet have reached sexual maturity. They’ll look for young fish again this fall.

The Gunnison River is lower in elevation, water temperatures are warmer and it is renowned for producing large trout. Brown trout – which are resistant to whirling disease – thrive in the river. The ponds on the Frying Pan River also provide relatively warm water.

George Schisler, another DOW aquatic research scientist, is hopeful that the next positive milestone will come in late 2008. “The fish need to make it to age one and beyond, so we’ll see this fall,” Schisler said.

But judging from research conducted on the Hofer strain, scientists are confident that the fish will survive and continue to reproduce.

Whirling disease is caused by a microscopic parasite that passes through the fish’s skin. The organism attacks the cartilage of young fish and distorts the spine. The affected fish move in a whirling motion, basically swimming in circles when excited or when trying to escape predation. This type of behavior greatly reduces their ability to survive in the wild.

The disease was found in Colorado in the mid-1990s and it devastated most wild rainbow trout populations throughout the state.

During a whirling disease seminar in 2002 in Denver, a German scientist delivered a research report about a rainbow strain that was resistant to whirling disease. The Hofer rainbow trout was raised in a German hatchery. The DOW moved quickly to determine if the fish could survive in Colorado. Early in 2003, DOW researchers worked with the University of California at Davis to import the eggs and start a brood stock at the Fish Research Hatchery near Fort Collins. The fish were exposed to the disease and then dissected to see how many parasite spores had developed.

Schisler said researchers were stunned by what they saw. Spore counts in Colorado River Rainbows – which have been used for stocking by the DOW for years – exposed to the disease could reach 4,000,000 per fish. The highest count in the Hofers reached only about 3,000 and did not affect the fish.

DOW aquatics staff then started crossing the Hofers with existing rainbow stock and conducting more tests. Not only were the new strains of fish resistant to the disease, they also grew faster than traditional stocker strains. Hofers grew to catchable size – about 10 inches – in about 14 months, four months faster than the other rainbow trout strains.

In 2004 fingerlings of the new cross strains were first released into the Gunnison River. They were first released into the Frying Pan River ponds in 2005 and into the Colorado River in 2006.

Some catchable-size crosses were also stocked in two reservoirs near Berthoud in the spring of 2006. The fish continued to grow in the reservoirs and anglers were successful in catching them.

Mark Jones, aquatic research leader for the DOW, said Colorado leads the nation in the whirling disease war.

“No other state has conducted more research into identifying real solutions to the whirling disease problem,” Jones said. “We could tell this was a good thing from the start.”

Based on the extensive research, the DOW hatcheries are expanding production of the various crosses. In 2008 more than 1 million sub-catchable and catchable fish of the Hofer crosses are planned to be stocked in lakes and rivers throughout Colorado.

Research to examine the resistance of the Hofer crosses to whirling disease and their ability to survive in the wild is ongoing.

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The Colorado Division of Wildlife is the state agency responsible for managing wildlife and its habitat, as well as providing wildlife related recreation. The Division is funded through hunting and fishing license fees, federal grants and Colorado Lottery proceeds through Great Outdoors Colorado.

JAN. 25 UPDATE ON DEER FEEDING OPERATION IN THE GUNNISON BASIN

The emergency feeding program by the Colorado Division of Wildlife in the Gunnison Basin is in full operation with feed being distributed to big game animals at more than 60 sites.
 
The program was started Jan. 13 because of extreme winter conditions in the area. Up to four feet of snow is covering natural food sources, and cold temperatures that have reached 40 degrees below zero are affecting the animals.
 
The feeding effort is being aimed at mule deer and pronghorn because their natural food sources are completely covered with snow. Elk, which are well-adapted to severe cold, are being provided hay in select areas only to keep them away from deer feeding sites and ranchers’ haystacks.
 
For the past 10 days Division of Wildlife personnel have been packing trails and roads into feeding areas with snow-cats and snowmobiles. Now that the snow on those trails is firm, feed is being taken into areas by snowmobile, snow-cat and on foot. Feeding is being done by DOW staff and volunteers. About 150 people have signed on to work as volunteers in the effort. At this time the DOW is not soliciting more volunteers.
 
Deer, which are naturally wary of people, are becoming accustomed to human activity and are starting to move to the feeding sites. Deer are being provided approximately 2 pounds per day of a specially formulated, high-energy feed.
 
Feed is also being provided to about 380 pronghorn in the basin. These animals, however, are notoriously skiddish and are difficult to draw to feed sites.
 
One problem facing wildlife officials is that some people are feeding deer inappropriate food. Deer are browsers, they survive mainly on shrubby-type vegetation. They cannot survive on hay, pet food, corn, birdseed, table scraps, etc.
 
“Unnatural food hurts deer more than it helps them,” said J Wenum, area wildlife manager for the Gunnison area.
 
If people want to help deer, wildlife officials recommend that property owners knock snow off of shrubs and pack down areas with snowshoes or skies to allow deer to move around in snow more easily.
 
Even though winter conditions are difficult in the basin now, snow came late which allowed deer to feed on natural vegetation until mid-December. Consequently, the body condition of many deer still appears to be good at this time.
 
Wildlife managers note, however, that the tough conditions will mean that mortality among deer will likely be higher than average. In a normal winter, 12 percent to 18 percent of the population will die. Most susceptible to harsh winter conditions are fawns and older age bucks.
 
“We’re not trying to save every deer in the Gunnison Basin. More deer will probably die this year than in average years. But our feeding program is meant to avoid a catastrophic die off,” Wenum said.
 
Colorado residents are reminded that the Colorado Division of Wildlife has posted a temporary emergency closure on wildlife-related recreational activities on public lands in the Gunnison Basin below 9,500 feet through May 15. Activities prohibited include all hunting and shed-antler collecting. Fishing is still permitted on Blue Mesa Reservoir and area streams. Collection of big horn sheep horns or skulls in sheep unit S70 is also prohibited. The full closure notice and a map can be viewed at the DOW web site: http://wildlife.state.co.us/WildlifeSpecies/EmergencyFeedingOperation2008.htm.
 
Anyone can make a donation to the feeding effort. Go to the DOW’s home page to donate on line or for more information:
http://wildlife.state.co.us.
 
 
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For more information about Division of Wildlife go to: http://wildlife.state.co.us.

Winter Feeding Programs Not Yet Necessary Outside Gunnison Basin
 
District Wildlife Managers and terrestrial biologists with the Colorado Division of Wildlife (DOW) are monitoring winter conditions throughout northwest Colorado to determine whether wildlife populations will need supplemental winter feeding.
 
“At this point we’re in fairly good shape,” explained Ron Velarde, DOW Northwest regional manager. “Fortunately, we are not seeing the difficult winter conditions that they are experiencing in the Gunnison Basin, nor do we have the same type of landscape.”
 
The DOW began a massive deer feeding operation in the Gunnison Basin more than a week ago. Deer around Gunnison are dealing with extreme snow depths, temperatures well below zero and a layer of hard-crusted snow that makes foraging for food extremely difficult. Additionally, the Gunnison Basin is an enclosed winter ecosystem and heavy snow leaves animals with no way to move to lower or more open terrain. Without the extensive feeding effort, many of the deer in the Gunnison area could face starvation.
 
“While we are seeing some very localized areas in the northwest part of the state that have heavy snow depths, there are readily available areas nearby those sites where sage brush and other critical food sources are available,” said John Broderick, senior terrestrial biologist for the northwest region. “We’ve also avoided the prolonged extreme cold temperatures and we aren’t finding heavy crusting conditions.”
 
District Wildlife Managers are monitoring herds in the Meeker, Craig, Steamboat Springs, North Park, Eagle, Middle Park and Aspen areas. Herd monitoring is accomplished in a number of ways. Wildlife managers can visually analyze body condition on deer and elk herds in their districts.
 
Wildlife professionals are also utilizing DOW airplanes to examine available habitat and animal tracks in remote areas.

For more information about Division of Wildlife go to: http://wildlife.state.co.us.