Tiger Trout Tiger trout are sterile hybrids of the brown trout (Salmo trutta) and the brook trout (Salvelinus fontinalis). Their name is derived from the exaggerated vermiculations that evoke a mental image of tiger stripes. Due to brook trout having 84 chromosomes and the brown trout 80 this hybrid rarely occurs naturally in the wild, although instances have been reported for decades.
Hatcheries are able to produce good numbers of tigers by fertilizing brown trout eggs with brook trout milt. However, the survival rate of the eggs is typically low, rarely exceeding 25%, compared to the 85% typically achieved with brown trout. Thanks to hybrid vigor, tiger trout reportedly grow much faster than either parentage.
Tiger’s markings are considerably different from their parents, and rather striking. The vermiculations of the male brook trout appear enlarged and twisted into a stripe-like pattern. Most also have a greenish cast, especially along the back.
Highly piscivorous (fish-eating), tiger trout are stocked not only for their sporting qualities, but also as a means of controlling stunted populations of brook trout and rough fish, such as suckers. Consequently, Utah Division of Wildlife Resources has been stocking them frequently, being sterile, they are able to control their population numbers also.
When fall water temperatures and day length perfectly align, brown trout are cued to begin their annual spawn. Providing the egg component, female brown trout are netted and her eggs are removed by gently stroking the fish’s belly in the direction of a vent, located just in front of the tail. Next, sperm from a male Trapper’s Lake brook trout is added to the pan along with a splash of water, to activate the fertilization process.