Sitting in his office at Montana Fish, Wildlife and Parks, regional fisheries manager Mark Deleray pulls up a map of the state’s waterways. It contains a smattering of green outlines, the largest of which covers the South Fork of the Flathead River and its wilderness tributaries.

“What’s unique about the South Fork is it is solely a native fish community,” he says. “What you have here is a pristine environment that has the same fish it’s always had.”

That’s not the case throughout the vast majority of the state, and in the rest of Western Montana there are only a couple of small, green outlines that represent the remaining streams where no fish have been introduced.

Tonight, Deleray and fisheries biologist Leo Rosenthal will give a free presentation at Flathead Valley Community College, discussing the history and current status of the South Fork’s bull trout.

“We have a fish here that is threatened under the Endangered Species Act, it’s a species of concern in Montana, but it’s a species that we have recreation opportunities with — we can allow limited harvest,” he explains.

While bull trout are catch-and-release only in the South Fork above Hungry Horse Reservoir, a catch limit of two fish per day has been in place immediately behind the dam for years. The total harvest averages between 50 and 100 bull trout each year, and surveys taken over the past three decades have shown the population to be holding steady amidst declines elsewhere.

East of the divide, several small drainages are still home to unadulturated native fish populations, but none rival the size or diversity of the South Fork. While Deleray’s pride for the pristine fishery is evident, protecting native fish species in Northwest Montana isn’t easy or cheap.

“A majority of our time is spent on native fish,” Deleray says of the agency’s regional fisheries division. “We’re different from other regions, and part of that is because we have native trout across the region.”

That stands in contrast to Montana’s southwest corner, where native trout exist but world-class sport fisheries take up more of the agency’s regional fisheries work.

During their talk, Deleray and Rosenthal also will present several minutes of underwater video of bull trout taken by biologists with the agency. The area is fortunate to have such a population of the rare trout, and observing the fish’s behavior in the wild is an experience few people get.

“The only way most people see the fish is if they catch it and pull it in,” he says. “We want to give people a glimpse of how those fish behave when they aren’t on the end of a line.”

The talk begins at 7 p.m. today in the Arts and Technology Building on the Kalispell campus of Flathead Valley Community College.

Reporter Sam Wilson can be reached at 758-4407 or by email at swilson@dailyinterlake.com.