BRETT FRENCH | bfrench@billingsgazette.com
Once the occasional oddity, tiger trout are ready to make a debut in Montana.
The sterile fish, a cross between a male brook trout and a female brown trout, are proposed for planting in four Beartooth Mountain lakes and seven central Montana reservoirs and ponds.
The Department of Fish, Wildlife & Parks announced proposals to stock the fish this spring in south-central Montana’s Region 5 in Crater, Lily Pad, Companion and Corner lakes.
“They can provide excellent sportfishing opportunities as they are aggressive and can grow to large size,” FWP wrote in its draft environmental assessment.
Region 4, in central Montana, has identified Bair, Crow Coulee, Hansen and Leningtons reservoirs as well as Maiden Spring, Kingsbury and Upper Carter ponds
The agency is touting the species ability to eat smaller fish, termed “biocontrol” — to winnow down the supply of stocked rainbow trout, self-sustaining brook trout and even nonnative fish like lake chub that may have been introduced after someone released their live bait.
“Since tiger trout are sterile, their numbers can be highly managed by stocking practices,” FWP noted.
Region 5 fisheries biologist Bryan Giordano said one of the goals is to increase angler opportunity, especially in waters where fish are so numerous that their size is stunted.
Stocking tiger trout, he said, will convert some of those smaller fish into more catchable-sized trout for anglers.
Triploid tiger trout eggs from Wyoming would be used as the source for stocking, the agency wrote.
“A triploid fish has three sets of chromosomes, unlike a fertile fish that have two set of chromosomes (a diploid fish),” according to Wyoming Game and Fish, which grows and stocks the fish. “A triploid fish is not a genetically modified organism nor have the genes of the fish been manipulated or modified in any way. Triploid fish simply have an extra copy of DNA that makes reproduction impossible.
“Triploid tiger trout are created by forcing the egg to retain a chromosome that is normally ejected during egg development. To prevent the egg from rejecting the chromosome, Story Hatchery personnel use a pressure treatment method to retain the chromosome that would normally be kicked out of the egg during an early stage of egg development. Using pressure, at precisely the right time in the egg development, the chromosome is retained; resulting in a sterile fish with three chromosomes.”
The lifespan of an individual tiger trout varies, but they generally live from 4 to 8 years. The fish average between 10 to 16 inches. The state record is a 4-pound, 20-incher caught in 1997 by Joe Sobczak from Bear Lake.
In 2018, Missoula angler Jake Lee caught a tiger trout while fishing Rock Creek. It was deemed a naturally occurring hybrid.
“I’m not surprised, but it is rare in the wild,” Pat Saffel, Region 2 fisheries manager for FWP, told a reporter at the time. “The two species just don’t overlap in area all that often, and they’re pretty distinct species.”
Angler Austin Christensen in neighboring Idaho caught a 27-inch, 9-pounder last year for a new state record. Wyoming also saw a new record set in 2024 when 13-year-old Jaxon Krall caught a nearly 13-pound tiger trout.
