How Have Slovenia's Rare Marble Trout Fared After Recent Disastrous Deluges?

Most people first see the radiant waters of Slovenia’s Soča River from afar. For my wife Christine and I, our first glimpse of the Soča occurred more than 5,000 miles from where the river flows. We watched a video on YouTube, mesmerized as an angler fought a marble trout from the river and drew it to their net. The trout had markings unlike any we’d seen and the water from which it came possessed an otherworldly clarity.

The Soča is a river with reach. Its beauty is so great, and its trout so unique, that anglers from around the world travel thousands of miles to fish its waters. Verdant hillsides rise above the Soča giving way to the skyscraping peaks of the Julian Alps. Picturesque villages dot its length. Straddling the Italian border in western Slovenia, the Soča is a fly-fishing Mecca for anglers across Europe who travel to test their skills against the native marble trout that course its waters.

The rivers of Slovenia have a radiance owed to the karst and limestone landscape through which they flow. White stones on the riverbed reflect the sunlight to create a luminescence that makes these waters among the most beautiful in the world.

When an opportunity arose to visit the Soča River in September of 2023, we were immediately intrigued. We began to plan a few days of fly fishing, looking over maps of the country, reviewing fishing regulations, exploring accommodations, and assessing our gear.

And then disaster struck.

Floods of the Century

In early August 2023, Slovenia was besieged by catastrophic floods that claimed the lives of at least seven people. Heavy rains in the latter half of July saturated the country. On the evening of August 3, a storm swept across Slovenia causing rivers and streams to breach their banks. Rivers in the Posočje and Upper Carniola regions were among the first to flood, with subsequent flooding affecting a broad swath of Slovenia, including the capital city of Ljubljana.

The worst flooding occurred in the foothills of the Julian Alps where more than 10 inches of rain fell in 48 hours. The resulting surge set rivers into a torrent, flooding numerous villages, shutting down transportation routes and causing widespread devastation. The event caused more than €7 billion (about $7.59 billion) in property damage. Slovenia continues to grapple with the aftermath.

We watched in disbelief as media reports depicted entire valleys flooded by raging rivers and villages inundated by floodwaters. Buildings swept from their foundations crumbled into turbid waters and cars bobbed through intersections like buoys on stormy seas. Deflated by the news, we were resigned to skip fishing the Soča but resolved to make the trip another time.

As the days passed and we tried to make sense of the news, we began to rethink the idea of skipping the trip. Our first concern was for the country itself. We didn’t want to make a bad situation worse by arriving in an area with stressed resources and damaged infrastructure. But the thought occurred that perhaps the flooding hadn’t impacted the entire country equally and that the Soča River Valley might have been spared the devastation wrought elsewhere. We also figured our tourist dollars might help a local economy undoubtedly affected by the bad news. We decided to email the Tolmin Angling Club, which manages the waters of the Soča, to get some solid information on the condition of the rivers.

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“Flooding did not affect western part as much as the rest of Slovenia,” wrote Blaž Močnik of the Tolmin Angling Club. “I would say in most rivers fly fishing is back to normal.”

The next day we booked a place to stay in Tolmin. We were on our way to the Soča.

One Shot for all the Marbles

Marble trout were once thought extirpated in Slovenia. The devastation wrought by World War II and the hard times that followed saw many residents turn to local waters for a source of food. The resulting pressure on the fishery, along with environmental pressures, caused a cataclysmic falloff in the marble trout population. Things began to look up with the formation of the Fishing Cooperative of Tolmin in 1947. Renamed the Tolmin Fishing Society in 1952, the group—known today as the Tolmin Angling Club—helped reestablish marble trout in the Soča River and its tributaries.

In the decades following the War, genetically pure marble trout were rediscovered in eight headwater streams of the Soča River drainage. The trout are again thriving in the Soča and other Slovenian waters, but their status remains precarious from the ongoing threats of dam construction, habitat loss, pollution, hybridization, and overfishing. The Tolmin Angling Club stocks thousands of marble trout in the Soča and Bača rivers each year in an ongoing effort to preserve these rare and wonderful fish.

We arrived in Slovenia on September 28, driving north from Trieste, Italy, through stands of forest broken by occasional swaths of farmland and rolling hills. We first glimpsed the Soča near the village of Solkan where it passes beneath an arched stone bridge. In its lower reaches the Soča’s flows are placid, inhibited by a series of hydroelectric dams that extend north to Most na Soči. But the beauty of the water was immediately evident, exhibiting a turquoise hue that was hard to take your eyes off.

Beginning in Tolmin and extending upstream to its headwaters, the Soča’s trout stream character takes shape. The river flows through forested hillsides, gorges, and meadows with every imaginable type of water from plunge pools and riffles to placid runs and heavy whitewater.

After arriving in Tolmin, we made our way to Soča Fly to purchase fishing permits and look over the selection of local flies. We learned the law actually allows anglers to cross private property to access rivers and streams. When we inquired at Soča Fly about the etiquette for crossing private property we were simply told to “be respectful.” A secondary challenge to reaching the rivers around Tolmin is finding a suitable place to park. The narrow roads require some perilous parking situations to adequately position your vehicle off the roadway.

While the Soča River is the undisputed main attraction for most anglers visiting Slovenia, the Tolmin region offers a lot more water to explore. Planning to save the best for last, Christine and I dedicated our first day in Slovenia to exploring the Koritnica and the Kneža. These streams are tributaries of the Bača, which joins the Idrijca before flowing into Lake Stausee near Most na Soči. As headwater refuges for marble trout, the regulation here is strict dry-fly fishing with barbless hooks.

The winding roadway out of Tolmin passes through small villages with glimpses through the trees to the cobalt waters of the Bača. It was tempting to stop and cast, but we drove on, eventually reaching a gravel road that paralleled the Koritnica. Unfortunately, flows were too low to find much in the way of fishable water, so we backtrack to the Kneža.

We found a gravel pullout alongside the river beneath the tree canopy and dropped down the bank to the river. A few casts later and I hooked into a modest marble trout of eight inches. It looked like porcelain as it turned on its side in the flow. I cradled the fish in my hand a moment while Christine captured a few photos before releasing it back into the Kneža. Christine took a 10-inch fish in the first deep pool we encountered, and we each caught a few more fish working our way upstream.

It was turning into a dream day of fishing. We were alone on the river in a beautiful setting catching native marble trout with dry flies on light tackle. Then I noticed a leaf drifting downstream in the current. And then another. A sudden push of water and a cloud of mud followed. We raced across the stream to reach the bank below the roadside and watched in disbelief as the once-clear Kneža transformed itself into an opaque torrent of debris. The rate at which the water rose was startling. The only thing we could imagine happened was a downpour somewhere upstream in the mountains.

As we descended the Bača we could see the debris from the Kneža churning in from upstream. Looking out at the hillsides, we noticed downed trees and muddy patches dotting the forest. Then it dawned on us that the impact of the previous month’s flooding was still influencing the rivers. Landslides and rerouted streambeds were all about. It wouldn’t be the last time we’d see a river turn in an instant.

With our opportunities nixed on the Kneža and Bača, it was time to head for the Soča.

Fishing the Soča River

The road out of Tolmin follows the Soča River north through the village of Kobarid and onward to Bovec offering anglers numerous access points to reach the river. Near Tolmin, the Soča is a wide river with riffles and pools. Further north, the road rises high above the Soča as it surges through a tight gorge popular with whitewater kayakers.

Christine and I accessed the Soča from one of the many boat launches along its length. While we didn’t see a single drift boat, it was clear that boaters outnumbered anglers by a wide margin. Before us, a broad riffle plunged into a pool with views of the distant Julian Alps rising above. A quartet of kayakers paddled through the pool casting a shadow through the water to the bottom. The only comparison I could draw in my mind was of a flats skiff suspended above the white sands of the Caribbean Sea.

Christine and I waded out on a rocky shelf to cast into the pool. The size, character, and structure of the Soča is reminiscent of the Yellowstone River in Montana, one of our home waters. Yet there was a sense of the unknown. We were both flummoxed and questioning our approach to this new and different river.

Then Christine saw a fish suspended in the tail of the riffle. It was swimming just below the surface rising occasionally to some unseen insect. It looked like a big fish. We tried a series of pile cast presentations letting the current draw our flies to the fish, but it refused our offerings. We sighted a few other trout in the pool and eventually took a decent rainbow trout on a streamer stripped through the tailout.

While it was thrilling to catch that rainbow, our hearts were set on marble trout. We walked upstream to look for another opportunity. Like the Yellowstone River, the Soča’s sheer volume means moving from pool to pool takes some time. We attempted to cross the river to reach a side channel but were denied by the force of the flow. Instead, we cut into the forest and found a trail that led us to a high bank overlooking the river.

With our new vantage point our approach to the fishery changed. The bottom of the river came into view and suddenly we could see each boulder, the passing shadows of clouds, and the gentle eddies where trout could hold. We slowed down and began to really look. And before long the marble trout started to appear.

The first marble trout we spotted was a fish of over 20 inches holding behind a rock no more than 10 feet from the bank. It was swimming languidly in the shadow of our forested bank, turning occasionally to take a nymph. I approached the fish from downstream but made the mistake of presenting my stonefly imitation to the bankside of the fish. It turned downstream to take the fly, but in the process saw me and spooked. We watched the fish swim through the crystalline flow 40 feet out and disappear behind a boulder.

The closeness of that fish was heartbreaking, but it gave us confidence that we’d see more marble trout. And we did. Over the next two hours, we spotted a number of sizable fish, including rising fish. I snipped the nymph off my tippet and tied on a size 12 olive Parawulff, a fly we’d later learn was grossly oversized for the fishery.

From our high-bank perch, Christine saw a large marble trout rising 20 feet from shore. There was seemingly no way to approach the fish without spooking it, so I decided to make a presentation from the bank. Somehow my steeple cast laced through the tight assemblage of trees behind me and the Parawulff fell delicately on the water within sight of the marble. The fish turned toward the bank and quartered downstream in pursuit of the fly. It went so far as to open its mouth, producing the slightest depression in the surface of the river below the fly before rejecting it at the last moment. We were learning that marble trout, at least in the Soča, do not come easily.

With several great opportunities at marbles and nice rainbow trout to show for our efforts, we decide to head back to Tolmin for the evening. We’d seen enough to have a strategy for the next day. On the way back to the carpark, we came to the run where I’d cast to the first marble we’d sighted earlier in the day. The fish had repositioned itself in the lie, and was rising.

“You’re turn,” I told Christine, handing her the rod. “I blew my chance at that fish. You’re going to get one cast to it. Get close. Be accurate. Make it count.”

Christine walked down the trail and dropped to river level below the fish. She crept up the bank and positioned herself for the cast. The Parawulff fell two feet above the fish, to the streamside. The marble turned away from the bank and slightly downstream. I watched as its massive jaws broke the surface of the river and swallowed the fly.

The sun was cutting across the valley as Christine set the hook. Moments later, in the shallows of the Soča River, she held the rarest trout we’d ever seen.

Sidebar: Fishing Families

The Tolmin Angling Club is but one of numerous fishing clubs throughout Slovenia. The country manages its fisheries through these clubs, also known as “fishing families.” Each so-called family manages a defined section of waterways. Regulations vary from fishing family to fishing family, as well as from river to river and sometimes even within stretches of river managed by a single family. The regulations can be a bit overwhelming, but you’ll get a detailed map when you purchase a fishing permit that details the regulations for the local waters.

Permits are expensive by U.S. standards. A daily fishing permit for the waters managed by the Tolmin Angling Club in 2023 was €67, around $70. The funds generated through permit sales fund the fishing families that are responsible for managing the fish farms, enforcing regulations, checking permits, and stocking local waters.

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Ben Pierce and Christine Marozick operate Side Channel Productions, based in Belgrade, Montana.