Dick Vincent works with Jennie Miles of Pony, who maintains the lab. Photo by Kelly Gorham.

Living the dream of an uber-angler, Dick Vincent once spent 10 hours a day, six days a week, fishing the streams of northwest Montana.

A Montana State University student in the 1960s, he cast his line-over and over for two summers-until he caught and tagged 4,500 cutthroat trout for researchers at the Montana Department of Fish, Wildlife and Parks. The process left him temporarily fish fatigued, but it led to a 42-year fisheries career that placed him at the forefront when whirling disease threatened to destroy the state's rainbow trout population.

Vincent, 68, retired this year after 12 years as whirling disease coordinator for the FWP, eight years as fish manager for Region Three of the FWP and 22 years as area biologist over the Madison, Gallatin and upper Missouri rivers.

Now focusing on miniature dachshunds instead of juvenile trout, Vincent left behind longtime collaborators at MSU and elsewhere who continue to search for solutions to whirling disease and other parasitic diseases.

Whirling disease infects about 150 streams across Montana, but Vincent said he is optimistic about the future of trout fishing in Montana. One of the most promising developments is the discovery of wild rainbow trout that are naturally resistant to whirling disease. Another is the mysterious rebound of rainbow trout in the first Montana river where whirling disease was discovered.

Into the wild

An MSU graduate who received his bachelor's and master's degrees in fish and wildlife management, Vincent started noticing in about 1991 that young rainbow trout populations were showing large declines in the upper Madison River. He didn't know why. As time went on, rainbow trout--especially young rainbows--continued to decline, so he met with top FWP officials to figure out how to tell the public that their blue ribbon trout stream was in serious trouble. By 1994, the rainbow trout population in the upper Madison had fallen by 90 percent.

"When I first heard of whirling disease, I didn't pay much attention to it," Vincent said. "I thought, 'OK, it's probably a hatchery disease and not really in the wild.'"

Testing proved him wrong.

A scientist friend was convinced that whirling disease was responsible for the rainbow trout crash in Colorado and suggested that the same could be true for Montana. As a result, Vincent sent some of the Madison River trout to a histology laboratory at Washington State University. The lab determined that whirling disease was, indeed, responsible for Montana's situation and set the course for the state's response.

FWP officials appointed Vincent their whirling disease coordinator in 1996. About the same time, Congress approved the Whirling Disease Initiative to find practical ways to maintain viable wild trout populations despite whirling disease. The initiative originated with a consortium called the National Partnership on Management of Wild and Native Cold Water Fisheries, administered by the Montana Water Center at MSU and provided funding for a variety of projects across the West.

Researchers whose projects were approved studied whirling disease from every angle they could imagine. Some investigated the two-host life cycle in fish and the aquatic worm Tubifex tubifex. Others analyzed the roles of water temperature, water quality and river sediment. The original goal was to understand how whirling disease worked, then eradicate it.

Whirling disease occurs when a microscopic parasite called Myxobolus cerebralis latches onto the skin of young fish, usually rainbow trout. The parasite then works its way into the fish and injects a series of infective spores into the muscle tissue, where the spores migrate to cartilage, the parasite's food source, Vincent said. The damaged cartilage causes severe deformities in the fish. When the fish's body tries to attack the parasite, it causes inflammation and infection within the fish. If most of the infection is on one side of the fish's body and causes nerve damage, the fish's brain can only communicate with one side of the body. Instead of swimming forward, the fish starts to whirl.

"Not a good thing to do when you are trying to escape a predator or eat," Vincent said.

Every infected fish doesn't whirl, but whirling disease got its name from those that did, Vincent said.

In the process of dying or being eaten, rainbow trout release Myxobolus spores into the water, Vincent said. Tubifex tubifex worms then eat the spores, which can survive in river bottom sediment or dry mud for up to 30 years. Within three to four months of settling in the worm's gut, the spore opens and a new infective version of the parasite emerges. It's called a Triactinomyxon or TAM. When the worms excrete TAMs into the water, the free-swimming TAMs start latching onto fish again. The cycle continues.

Return to regular view	Text-only              Email this article	Published: 4/27/2009