A slight breeze is kicking off the water, and the stars beam brighter than the house lights dimly visible along the shoreline a half-mile away. David Gilroy kills the engine and I begin making my way to the bow of the small boat. It’s about nine o’clock at night, and even though it’s summer, I’m wearing a long-sleeved shirt. Fallen Leaf Lake lies 6,000 feet above sea level on the eastern side of the Sierra Nevada, and the air is practically glacial.

With me are two fisheries biologists. Gilroy is a graduate student at the University of Wisconsin, and Sudeep Chandra is from the University of California, Davis.

As I slowly stand up, trying not to rock the boat, the flashlight Chandra is holding illuminates the large buttons running down the front of my shirt —perfect for snagging on the net I’m holding. Back at the dock, Chandra had jokingly warned me about getting tangled up in it. “It’ll pull you into the water,” he said. “You saw that movie The Perfect Storm didn’t you?”

Fallen Leaf Lake is deserted at this hour, and the surface is smoother than any of the blacktop roads hugging the surrounding mountainsides, but his comments make me a little nervous. Steadying myself, I fling the net into the black water. Gilroy begins slowly backing up the boat as I feed the mesh over the side, trying to keep it from tangling.

Chandra stands off to my side, shining a flashlight on my work, and I watch as the lake slowly swallows the rope and monofilament, dragging it down 300 feet, where it will balloon like an underwater volleyball net. There it will hang, waiting to trap the alien predator that has been gobbling up the fish of Fallen Leaf Lake.

Fallen Leaf lies within the Tahoe basin, and it is now ground zero for a restoration program for the native Lahontan cutthroat trout. Everyone within thirty miles seems to be involved; the short list includes the U.S. Fish and Wildlife Service, the California Fish and Game Commission, Tahoe City, the Tahoe Regional Planning Agency and the U.S. Forest Service, which manages much of the trout’s original habitat. Chandra and Gilroy are part of a university research team supplying the science that holds these special interests together.

The Lahontan cutthroat trout has ranged up and down the Tahoe watershed for close to 200,000 years. It was big for an inland salmonid; some weighed more than forty pounds. It’s thought they lived in lakes and ventured into streams to spawn, although some strains may have spent their entire lives in rivers and creeks. Whatever the history, there’s a good possibility that a fish spawned in Nevada’s Pyramid Lake migrated eighty miles up the Truckee River to Lake Tahoe.

The Tahoe basin formed 2 million to 3 million years ago when the earth’s crust began to crack along what is today the border of California and Nevada. As large blocks of crust sank, forming the basin’s floor, other landmasses pushed upward around the rim, creating the Sierra Nevada on the west and the Carson Range along the east. A volcano later belched out a wide river of lava, plugging gaps and holes.

Centuries of snow and rain began filling the valley and eventually shaped the ancient shoreline of Lake Tahoe. During the last ice age, which ended about 20,000 years ago, glaciers crept down from the mountains, scouring the basin’s granite bottom, digging up rocks and boulders and pulverizing many of them into dirt and sand. When these glaciers retreated 10,000 years ago, they sloughed off these piles of rock and dirt, leaving behind what is called a glacial moraine.

One glacier dumped a moraine on the southwestern end of Lake Tahoe, blocking an inlet and creating Fallen Leaf Lake. Otherwise, this small alpine body of water would have remained another finger of Lake Tahoe.

On its southern end, Fallen Leaf Lake is fed by Glen Alpine Creek, a rocky brook that funnels the rain and snow falling thousands of feet above in the Sierra. Fallen Leaf Lake is not large, maybe a mile wide by a couple of miles long. The Forest Service land that surrounds the lake is interspersed with private property; houses line the southern and eastern shores. On the northern end, Taylor Creek punched a hole through the ancient moraine, winding through a mile of rocky soil populated by ponderosa pines, white fir, Jeffrey pines and aspen before spilling into Lake Tahoe.

Lake Tahoe’s only outlet is the lower Truckee River, twenty miles away on the northwest shore. The Truckee courses over eighty miles and drops 3,000 feet before settling down in the high desert of Nevada at Pyramid Lake. Pyramid is a dead end lake, a tiny remnant of the once vast, prehistoric Lake Lahontan, which stretched across 8,000 square miles of present-day Nevada.

After setting five more nets, we dock the boat and the three of us jump into Chandra’s truck. He starts it up and we sit waiting for the heater to kick in. His weimeraner has wormed its way onto our laps and Gilroy is cradling the dog’s head. Chandra starts to explain the Lahontan cutthroat’s history and how this netting study is part of the recovery plan.

White settlement came to Tahoe in the 1840s, and pictures from the turn of the century show huge catches of twenty-five to thirty fish per person. But at the same time settlers were harvesting from this bountiful fishery, they also set about trying to improve it. Records show that the first fish imported into California was the common carp in the early 1870s, and when the intercontinental railroad was completed in 1872, things broke loose.

Settlers pouring into the western frontier transplanted familiar, but invasive, fish varieties. Rainbow, brook, and brown trout (an import from Germany) were stocked throughout the Sierra.

Dams began springing up along the rivers, helping to power the many new sawmills. The first dam near Lake Tahoe was built at the outlet of the Truckee River in 1870, and dams that came afterward changed the river’s course, forcing migrating fish to bypass sawdust bars at the river’s terminus above Pyramid Lake.

With so much human activity in the Tahoe basin and the Truckee watershed, it would be hard to place blame on a single factor that led to the cutthroat’s demise. It could have been the logging and overfishing, or it may have been the dams. Aggressive introduced species certainly didn’t help, and some scientists speculate that foreign fish may have carried a fatal disease. Regardless, by 1917, fishing of Lahontan cutthroat trout was banned on Lake Tahoe; and soon after, the state of California began a hatchery program to keep the fish from vanishing. This effort proved fruitless, and 1938 was the last year anyone saw Lahontan cutthroats spawning in the streams of Lake Tahoe.

Cutthroats did manage to hold on in some isolated alpine lakes, such as Independence and Cascade. In the 1960s, a strain of Lahontans was discovered swimming on the western side of the Sierra Nevada in Macklin Creek, apparently planted there a hundred years previously by a shepherd or logger. A decade later, a biologist stumbled on some wayward Lahontans in a stream close to the Nevada-Utah border. These fish were a rare find: genetics show they are closely related to the fish that once swam the Truckee River. The stream’s location remains a secret. The Lahontan cutthroats were federally listed as a threatened species in the early 1980s.

Which brings this story to a dark bar with a pool table and jukebox music playing in the background and a large lake trout mounted on the wall. Sitting at the bar were Chandra and a couple of scientists, including Jake Vander Zanden, a professor at the University of Wisconsin Center for Limnology. The fish on the wall soon became a topic of discussion.

Lake trout are an import from the Great Lakes, and they are now the top predator in many western lakes, including Tahoe. The trouble with the lake trout is that they probably kill off the native fish, lying in deep water to ambush anything up to half their size. The scientists at the bar had been working on a project to see if this was true, and the evidence they needed, it turns out, was a small chunk of tissue off the backside of that trophy fish.

From a small sample of flesh, scientists can get a good idea of what a fish ate. They do this by measuring the carbon and nitrogen found in the muscle. By comparing isotopes of carbon, they can figure out whether a fish was feeding along the bottom or in the open water. Nitrogen isotopes tell more about what a fish was eating. By analyzing nitrogen in a sample of fish tissue, scientists can tell if a trout was predating on other fish or if it fed more often on small plankton, like mysis shrimp or daphnia. The chunk of flesh from the lake trout displayed above the bar became one of the many specimens of tissue gathered from fish that had been caught over the years in Lake Tahoe.

At the lab, Vander Zanden found that the lake trout are voracious predators, feeding almost exclusively on fish swimming below 120 feet. Measurements taken from museum specimens of Lahontan cutthroats show that these native trout were less predatory, preferring small plankton, such as daphnia and bosmina. Also, the Lahontans were less likely to feed off the lake’s bottom, usually schooling in shallower depths.

What this means is that the Lahontan cutthroat and the lake trout could conceivably coexist in Lake Tahoe. Their range would overlap and the lake trout would probably prey on the occasional Lahontan that ventures into deep water, but there is the possibility of restoring the native cutthroat. But before trying to reintroduce them into Tahoe, scientists want to work out the kinks on much smaller Fallen Leaf Lake.

The next morning we’re back on Fallen Leaf Lake. Pulling up the rope attached to the first net, I can feel my hands wanting to cramp. Two-thirds of the rope is in the boat and the net is still a hundred feet below us. When I finally reach it, Chandra helps me pull it in. Two large lake trout are struggling in the mesh, and it’s a frustrating chore to unwrap them from the tangled filament. They’re large fish, and we’ll catch many more as the day progresses, but for the moment, we place them in a cooler so they can later be measured, weighed and sexed. Cutting open their stomachs will reveal what they’d been eating.

We head to the dock to offload nets, and Chandra drops me off so I can chat with Bill Craven, an old-timer whose family has lived in these mountains since 1895. He also happens to be a wealth of information and a capable citizen scientist. Every day he e-mails the University of Nevada with the water temperature and local weather conditions of Fallen Leaf Lake.

We step onto his back porch, which juts over the water. The sun is out, reflecting off the house’s large windows as chickadees and nuthatches mob his nearby bird feeder. Occasionally, a chipmunk dashes into view and grabs a sunflower seed, and I spot a flock of mergansers thirty yards away diving for fish.

Fallen Leaf Lake sports million-dollar homes that rent for thousands of dollars a weekend, but one of the first structures was his grandfather’s hotel, Fallen Leaf Lodge. Once a summer resort for Californians, it is now a retreat for Stanford University alums.

At the turn of the century, he says, there was a commercial fishery for Lahontan cutthroats on Fallen Leaf Lake. The fish were iced and shipped to San Francisco and even made it to dinner tables as far away as Chicago and New York. The fishery died by 1914, but Craven remembers that as a young boy wielding a fishing pole, he reeled in introduced species like rainbows, brooks, browns, kokanee and mackinaws, the name locals give to the lake trout.

Though Craven never saw the Lahontan cutthroats, his mother told him they would roam from Tahoe up Taylor Creek and into Fallen Leaf Lake before journeying up Glen Alpine Creek to spawn during the spring.

Down at the dock, Chandra and Gilroy have hauled in the nets and are talking about their catch. Among the lake trout are a couple of Lahontans planted during the spring as part of the restoration process. The cutthroats, Chandra says, were pulled from nets at different depths than the lake trout, a sign the two species might be able to live together. Brant Allen, another fisheries biologist from Davis, has been snorkeling around the boat docks and seems to think that the cutthroat fingerlings planted during the spring are also doing a decent job of avoiding predators, including the mergansers.

It’s too early to tell, but with careful management–introductions of Lahontans and a continued moratorium on the stocking of browns, brooks and rainbows—cutthroats may make a comeback in Fallen Leaf Lake. That’s what the scientists want to figure out: the right conditions to make this possible. They can then take these lessons and apply them to the much larger Lake Tahoe and its many streams and rivers.

I get into my car to leave and drive along the western edge of Lake Tahoe to catch Interstate 80 back to San Francisco. Thinking about the restoration effort, I can’t help but find it odd that people have spent decades and millions of dollars stocking Lake Tahoe and the surrounding lakes with all sorts of alien species to try to make them better places to fish. Now here is a new generation at the turn of another century, starting all over again with the Lahontan cutthroat trout.

For some time, the road runs alongside the Truckee River as it tumbles down the mountain on its journey into the desert before spilling into Pyramid Lake. Looking through the car window, my eyes trick me into believing that I’m seeing a wild river, gorgeous and savage, even though I know it’s a tame shadow of its former self. But I can’t help but wonder if someday, maybe a hundred years from now, spawns of Lahontan cutthroats might be battling their way up the Truckee, dodging rocks and fishing lures, fighting the currents and eddies and finning their noses at the passing motorists hurrying to the blackjack tables in nearby Reno.