A decade or so ago, some of Utah's top fish biologists began looking at rearing hybrid fish that could: first, challenge whirling disease; and second, be a management tool.
Some, like the "brownbow," a cross between a rainbow and brown trout, never made it. By the time the fish reached one year, all had cataracts in their eyes.
Two that have assimilated successfully into Utah's fish population are the "splake" and "tiger trout."
And, in recent years, both fish have become popular targets for anglers' lures.
The splake, a cross between a lake and brook trout, is best able to fight off the disease, but its range is limited. It cannot, for example, be planted in some mid- and low-elevation waters.
The tiger, a mix between a brown and brook trout, is not as impervious to whirling disease. It is, however, more adaptable and, at this point, possibly more popular.
While both fish are aggressive and tasty, it is the tiger that got the looks. The tiger is a strikingly beautiful fish. It features a maze of dark stripes, thus the name tiger, which are stenciled over a body of pale green and gold. Its lower fins are a yellowish orange.
One reason for its popularity is its rarity. There haven't been that many available to catch.
Now, because of better growing conditions at the new Fountain Green hatchery, and on-going work at the Egan Hatchery, more tigers will be available this year.
Before the new Fountain Green Hatchery was finished, only about 15,000 tiger trout could be raised. "But with the newly-constructed Fountain Green Hatchery facility, we are raising over 300,000 tiger trout this year alone," said Eddie Hanson, hatchery assistant supervisor.
Because the fish are hybrids, in this case a mix of a female brown trout and male brook trout, it takes an intensified effort simply to get eggs to hatch.
To help, said Don Bone, Egan hatchery manager for the DWR, "We've been able to keep a larger brood stock — more browns and brooks — and were able to collect more eggs this year, therefore we were able to raise more tiger trout." Only about 35 percent of the eggs collected will eventually hatch.
Because the tiger is a hybrid, it is sterile, which means it can't reproduce. This means numbers can be controlled and, more importantly, certain species can be guaranteed homogeneity.
Which means, pointed out Chris Wilson, director of the DWR's Fish Experiment Station in Logan, tigers can be planted "and we know they won't reproduce and cause problems or cross for other fish, like the cutthroat."
In Strawberry, for example, sterile rainbow are planted along with fertile cutthroats. This guarantees the two will not cross breed and therefore maintains the aggressive nature of the cutthroat.
This can be particularly important in waters that hold the Colorado cutthroat, which is a native Utah fish that is currently on a recovery program.
With fertile strains, this is not always possible. There are "cutbows," for example, which are a cross between a cutthroat and rainbow, occurring naturally in open waters. Which is why, added Wilson, "We refrain from putting rainbow in streams with native cutthroat."
Tiger trout are now found in approximately 40 fishing waters throughout Utah, including Huntington, East Canyon, Hyrum, Joe's Valley, Palisade, Rockport and Panguitch Lake.
Because of the unique look and aggressive nature of the fish, it won't be hard for fishermen to know when they've got a tiger on the line.
E-mail: grass@desnews.com