"We have focused on one probable cause, which is the presence of birth control hormones in our waterways. The hormones used in “the pill” and “the patch” have seeped their way into the Madison and Bitterroot drainages, and are now found to range from 3 to 7 ppb (parts per billion) in our water. One of the hormones (alpha-g7) has causes DNA mutations in Salmonid populations. Some of these mutations have opened the gateway to cross breeding, and we have the Mountain Brownfish to show as a result”, says head of fisheries, Dr. Tyler Laurenti. "
Brown Trout X Mountain Whitefish Hybrid, A New Species?
In a recent electro fishing study, a new hybrid fish species has turned up in alarming numbers in the lower Madison and Bitterroot drainages of Western Montana. Scientist concur, this is without a doubt, a cross between the Mountain Whitefish (Prosopium Williamsoni) and the Brown Trout (Salmo trutta).
DNA testing has shown that the sample fish taken from the lower Madison drainage contain an alarming pattern. Some of the data is consistent with both Brown Trout and Mountain Whitefish while other DNA sequences do not match with any known Salmonid.
The Montana Fish & Game has this to add; “The cross is not implausible, Whitefish and Brown Trout spawn within the same time frame, and commonly utilize the same riffles for Redd construction” says Biologist Chris Daniels. Unlike the rarely occurring natural cross of Brook Trout (Salvelinus fontinalis) and Brown trout, the White Fish Brown Trout hybrid cross seems to be occurring with alarming consistency.
Densities of these fish, now being called “Mountain Brownfish” range from approximately 200 to 500 fish per mile in the lower Bitterroot and Madison drainages. This seems to be a new phenomenon, because in studies conducted before March 17, 2005 the presence of this Mountain Brownfish had not been noted.
The Fish and Game provided a few explanations for the sudden appearance of these strange Salmonids. “Small fish do not seem to be affected by electro shocking, in fact we rarely capture any trout under 6 inches while doing surveys in the Madison Drainage. We captured Mountain Brownfish ranging from 6 to 23 inches in our surveys this spring. Through studies of the inner ear bone and scale samples, we concluded all of these fish were from the Fall 2003 and Fall 2004 year class.
Common knowledge dictates that Salmonids would not reach anywhere near this size in one and a half or even a half-year. The Mountain Brownfish has exceptional growth rates as far as we have observed. In fact we have concluded that from birth, it can increase its size as much as 2.5 inches per month. The explanations for why these fish have suddenly popped up in surprising numbers in two of Montana’s most used drainages have spanned the gamut. We have focused on one probable cause, which is the presence of birth control hormones in our waterways. The hormones used in “the pill” and “the patch” have seeped their way into the Madison and Bitterroot drainages, and are now found to range from 3 to 7 ppb (parts per billion) in our water. One of the hormones (alpha-g7) has causes DNA mutations in Salmonid populations. Some of these mutations have opened the gateway to cross breeding, and we have the Mountain Brownfish to show as a result”, says head of fisheries, Dr. Tyler Laurenti.
A low-level intern, Marc Crapo, shares these interesting facts; “Even more alarmingly, the Mountain Brownfish has proven to be capable of reproduction, unlike other hybrid species we have observed. Some of the smaller Mountain Brownfish have shown slightly different DNA patterns than the other samples, which indicate these are offspring of both male and female Mountain Brownfish. By the way, does anyone have a beer?” It appears that the Mountain Brownfish is here to stay, which may not be a bad thing.
The Brown Trout are considered a world-renowned sport fish. They draw billions of dollars to fisheries every year because of their intelligence and fighting ability. A few people eat Mountain Whitefish, and sometimes they swim in a circle when hooked in the tail.
Biologists were hoping that the Mountain Brownfish would mirror the trails of the Brown Trout, but the opposite seems to have taken place. “The Mountain Brownfish is the worst game fish on this side of the Mississippi. I myself would rather catch a carp. These fish share the poor fighting ability of the Mountain Whitefish, and the intelligence of a Brown Trout. They are amazingly difficult to catch and I’ve had better fights from a stick. Anyways, where is my ten bucks, I’m like totally out of gas dude,” replied the self proclaimed “trout bum” by the name of Ryan Davey. Biologists agree that this new fish will rarely appear in creel surveys, because of its difficulty to catch.
The future seems uncertain for some of Montana’s most well known fisheries. The Mountain Brownfish has proved to be such a voracious feeder that the insect biomass in the sections of the Madison and Bitterroot rivers that this new fish has been found have decreased sharply. Noted Biologist and Author, Robert Benke, predict that the Mountain Brownfish will have a negative effect on other Salmonid species that it shares habitat with. “The food supply will simply not be able to support these new feeding machines. Mountain Brownfish may lead to the downfall of less aggressive native Westslope Cutthroat Trout.”
It appears the future for Montana’s waterways is none to bright. This new species is just one of many hurdles the fish and game will have to overcome. If the Mountain Brownfish is not eliminated or controlled in the Lower Bitterroot and Madison drainages, it may end up leading to the downfall of Rainbow, Cutthroat and Brown Trout.
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