''Cranebow'' program may result in more, bigger fish for anglers

Posted: Wednesday, March 14, 2001

SUNRIVER, Ore.(AP) -- Central Oregon anglers are getting ever nearer the trophy rainbow trout which swims elusively through their dreams. Not because of a new lure, but because of a new fish:

''Cranebows.''

The Oregon Department of Fish and Wildlife's ambitious cranebow program, now in its fourth year, cleared a big hurdle this winter when biologists spawned the first batch of cranebow brood stock at the Fall River Hatchery.

''This will be an important step, if it's successful, as far as meeting our angling goals,'' said Steve Marx, a Bend-based biologist with the Oregon department.

The brood stock cranebows average 5 pounds, with some up to 8 pounds. They are part of the department's long-range plan to replace current hatchery stocks, which are not native to the area.

The hope is that the larger, more robust cranebows will eventually be used to stock all Central Oregon waters where stocking takes place. The cranebow program also meets an ODFW directive to use fish stocks indigenous to the area. Those are expected to be more successful at surviving in the wild than the non-indigenous species currently being stocked.

The result could be more and bigger fish for anglers.

Cranebows are trout that originated from wild trout in Crane Prairie Reservoir southwest of Bend. Beginning in 1997, the ODFW has each January through April snowmobiled to remote locations to capture wild rainbow trout that were making spawning runs up tributaries of Crane Prairie Reservoir. From those trout, biologists collected 50,000 eggs in 1998, and 185,000 in the next two years. More eggs are currently being collected from wild trout to provide a supply of wild genes for the captive program.

While most of the eggs taken in previous years were eventually raised into fish that were released into either one of several Oregon lakes or the Deschutes River, some were retained at the hatchery for brood stock.

In January, those fish became the first captive cranebows to spawn another generation, significantly boosting the number of eggs the biologists have to work with. If those eggs prove viable in producing another generation of cranebows, the ODFW will be closer to replacing currently used hatchery fish.

''Depending on results, it will be a fairly important step in meeting allocations if we move into production scale,'' said Marx. ''Basically, were using hundreds of thousands of fingerlings (to stock Central Oregon waters). To get to that, it's going to require this captive brood stock to support that program.''

The ODFW has already cleared some big hurdles in pursuing its goal of producing cranebows. But, said Marx, there are more hurdles ahead. Checked off the ''to do'' list is the ODFW successfully taking eggs from wild trout and then successfully raising them in hatcheries to spawning size.

Future obstacles for cranebows include determining if the eggs of the brood stock are viable and can be raised to release size.

Also, the department wants to find out if the cranebows, once released, will survive in the wild, and if they will come to an angler's offering with some regularity.

''Everything looks good,'' said Marx. ''But a lot of the little wrinkles don't show up until you actually do it.''

One wrinkle did surface in the last batch of cranebow brood stock. Only about 25 percent of the females were ready to spawn, which resulted in about 70,000 eggs from 25 fish, Marx said. Biologists now have to wait for more of the cranebows to come into spawning condition.

''That's something we learned,'' noted Marx. ''The maturation process for that captive brood may come at different times.''

Another wrinkle was the unexpected appearance of bacterial kidney disease last fall in cranebows at the Oak Springs Hatchery near Maupin. Several hundred of the 31,000 cranebows died as a result, and stocking programs had to be altered to make sure the fish didn't bring the disease into any river systems.

On another front, sampling last summer at Big Lava Lake found encouraging data on cranebows. A live trap resulted in the capture of 64 trout, and 22 of them (35 percent) were cranebows. Cranebows also represented 58 percent of the captured trout that exceeded 11 inches in length.

Considering that cranebows accounted for only 20 percent of the total number of rainbow trout released into Big Lava Lake in the previous three years, the data suggests that cranebows have a better prognosis for survival and growth than the current hatchery stock.

Still, that sample was too small to be conclusive, so more studies are planned this summer. That information will tell biologists what hurdles lay behind and ahead.

''We've come a long way,'' said state biologist Ted Wise. ''But we still have a long ways to go.''

(Distributed by The Associated Press)



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