Sea trout fishing is often shaped by tradition, habit, and long-held beliefs passed down through generations. But what happens when you challenge those assumptions and start from scratch? In this interview, we speak with a passionate coastal angler behind the Seatrout Science project—a year-long experiment that combines observation, data, and relentless time on the water to uncover where sea trout really are, and how we can fish more effectively for them.
BY THE EDITORIAL STAFF
Can you tell us a bit about your background as a sea trout angler?
As the son of a sea trout angler, I was raised on stories of big fish—some that were landed, but most of them, and especially the biggest, were lost after long, difficult battles. In my imagination, I had already caught many large, silver sea trout before I finally landed my first one—a 40 cm fish—on a spring day in 1980, at the age of 10. I had begged to join the trips for a couple of years, but my father and grandfather insisted I had to wait until I turned ten. That led to a few teary moments when they left and I had to stay home. But looking back, it helped ignite a fire in me that has been burning ever since. The urge to head for the coast—no matter how hopeless it may seem—was built during those years. The experiences are out there by the water, not on the sofa.
My grandfather was very meticulous about reading nature’s signs. Back then, there were no tide tables readily available, so we would always place a stick at the waterline to see whether the tide was rising or falling. He also quickly taught me to read currents, seams, and seasonal food sources.
In the early years, it was all spin fishing. But after some time, I became curious about fly fishing. For the next 15 years, I used both spinning and fly gear, often letting the conditions decide which method to use. At some point, I reached a kind of saturation with spinning, and gradually the fly rod became my primary choice. Around that time, I noticed a decline in sea trout numbers—but only for a relatively short period. I then realized how important location is, and that the spots successful for spin anglers are rarely the same as those for fly anglers—and vice versa.
What was the turning point that made you and Lars Henriksen approach sea trout fishing scientifically?
It was a beautiful spring day—warm, with birds singing. We had been fishing for two and a half days without results that matched our effort. After another fruitless session, we sat on the shore enjoying a beer, clearly frustrated by the lack of fish. Since we both work professionally with people—where frustration is often part of life—the conversation naturally shifted toward problem-solving. What parameters could we adjust?
As part of any analysis, observation is key. So we agreed that during the next session, one of us would fish while the other observed. We immediately put this into practice—first I fished while Lars observed, then we switched roles. Afterward, we sat down for another beer and reflected. The conclusion was obvious: despite catching nothing, we kept repeating the same behavior—wading out to waist depth, casting at a 75–90° angle to the shore, retrieving steadily with slight variation… maybe. Our discussion covered everything: open coast versus fjord fishing (we were in a fjord), bottom conditions, food sources, fly selection, retrieve, and especially the depth we were fishing.
Suddenly, Lars stood up, finished his beer, and said: “Now I’m going to do the exact opposite.” He walked just two meters into the water and started casting parallel to the shoreline. The bottom consisted of sand with scattered bladderwrack, and the depth close to shore ranged from 10 to 40 cm—a classic South Funen fjord. I was still finishing my beer when Lars shouted. Thirty meters down the coast, he was bent into a fish—a 45 cm sea trout thrashing on the surface. Two hours later, we had landed nearly twenty sea trout up to 50 cm—all caught in less than 40 cm of water.
That evening, back in the cabin over another beer, we debriefed. We realized how much our fishing was governed by habit. Two and a half days with just enough fish contact to keep us stuck in a kind of unresolved frustration—a trance-like state that is, unfortunately, not uncommon among sea trout anglers. That moment marked the beginning of a long series of conversations about how little we actually know about sea trout—and how much of our approach is shaped by inherited dogma. What is true, and what is just rigid habit?
One thing became clear: we needed to dig deeper—not only into the fish, but also into the psychology of the angler. And to do that, we first needed solid facts about the sea trout.
Can you explain the basic idea behind Seatrout Science?
As we became more aware of how deeply rooted our bad habits were, we began shaping a vision for what to do with our “discovery.” It’s not new knowledge that sea trout can be found in shallow water at certain times of the year. But our new insight raised questions. The first was simple: what is “shallow water”? The answer somehow just hung in the air—because who but the sea trout can truly answer that?
Of course, we had our own ideas—but they were just guesses. Even highly skilled anglers could offer no more than educated guesses. So we needed a way to force the answer out of these secretive fish. That marked the beginning of a deeper awareness of how we fish. It became essential to standardize our approach so that the data we collected would be as reliable as possible.
Our hope was that a solid base of raw data could provide clearer answers about where—and especially when—we can find sea trout.
What answers were you looking for?
After several unproductive days—not for the first time—our initial goal was to understand how close to shore sea trout actually come, and how often they are there. Naturally, the next question was how important water depth is. We had already experienced fish in just 10–20 cm of water, but it seemed counterintuitive. We both had this idea that a sea trout in such shallow water would have nowhere to hide. But we were about to learn otherwise.
We also knew that seasons play a major role. The fish we target in spring behave very differently from those in autumn—even though they are the same fish. Here too, we discovered surprises.
How did you approach collecting data? (What dogmas were you challenging?)
Once we realized how much our habits controlled our fishing, it became necessary to set strict rules. The first challenge was what we called “the pull of the horizon.” The horizon seems to act like a magnet for anglers—the unknown, deeper water where we imagine the big, mysterious sea trout must be. We felt this force constantly pulling us outward. After only a few casts in ankle-deep water, we would unconsciously start wading deeper and casting farther out.
The second challenge was casting angle. We had observed a nearly mechanical, trance-like behavior—not just in ourselves, but in most anglers we met: casting straight out toward deeper water, rarely parallel to the shore or inward.
To gather useful data, we needed to systematize our fishing method. So we created a set of rules:
- Never wade deeper than ankle depth—preferably fish directly from shore.
- Cast in a half-fan: one cast parallel to shore, then at 30°, 60°, and 90°.
- Fish with the wind along the coast. Take one or two steps, then repeat the pattern.
Since we were interested in how far from shore fish were striking, we also limited casting distance to a maximum of 20 meters, including leader. Later, we discovered that this limitation had unexpected advantages. We also wanted to know the depth at which fish struck. This posed some challenges, but our rule was to wade out afterward and measure the depth at the estimated strike location.
Of course, fish can follow the fly, but they can also come from shallower water—so we considered this method sufficient to build a picture of how shallow sea trout actually hunt.
Another important factor was tide. We had both been told countless times that tides strongly influence fish activity. Some older anglers would even cancel trips if the tide didn’t match their expectations. Naturally, we had to test this assumption.
We distinguished between tidal movement and actual water level (high/low tide). Our observations mainly came from apps like DMI, Sejladsudsigten, and Fishing in Denmark. Since these are based on algorithms rather than direct measurements, there was some uncertainty—so our most important observations were always those we made ourselves on the coast.
To avoid bias, we only checked tide and water levels after each fishing session.
Finally, we needed to define the fish in our data. Only sea trout of 30 cm and above were included, divided into size classes: 30–40 cm, 40–50 cm, and so on. This gave us a clear picture of the actual size distribution of the fish we catch.
Were there specific theories or hypotheses you wanted to confirm or disprove?
Throughout the project, I think we became increasingly aware of how theories are passed from angler to angler. How older members in fishing clubs influence younger generations. How fishing buddies affect each other—even in the smallest details—and how tackle dealers help shape preferences for gear.
Many theories are built on weak foundations and, over time, turn into “laws” of sea trout fishing. The most common one we encountered was the classic explanation for poor catches: “The sea trout were too far out today.” A typical conclusion after eight hours of standing in water up to your waders, casting long distances toward the horizon. This was a dogma we had to challenge. Clearly, there were exceptions where sea trout were right in the surf zone—but was that the exception, or the rule? And was the idea that they stay far out actually the exception?
It became a journey into the theories and beliefs that had formed the foundation of our fishing for many years. We were both reasonably successful anglers, but the feeling that we were overlooking something kept nagging at us. There was untapped potential that needed to be uncovered.
As we dug deeper, we realized how easily these ingrained habits form—and how they can evolve into a narrative that fishing is getting worse year by year. In reality, sea trout fishing is constantly changing, and habits can become so fixed that you fail to adapt before the seasons shift and the fish move on.
Behavioral researcher Daniel Stern’s theories on how habits become ingrained reinforced our belief that we were onto something interesting. The question was whether it was even possible to change our own bad habits—without bringing a psychologist along on fishing trips.
It turned out to be quite a challenge, and without regular discussions over the phone, it would have been difficult to stick to the new rules (or habits) we had set for ourselves.
How did the data collection process unfold—and did you face challenges along the way?
Since it was important to have support from home, we called our wives in for a “meeting.” I think they understood that we were serious. To collect enough data over a year, it meant that all our free time would be spent on the coast. Even short morning and evening sessions had to be used whenever possible. There were a few raised eyebrows—but we got the green light. Now it was time to fish.
From January 1st to December 31st, 2020, we fished relentlessly. Every trip was documented using a form we filled out after each session.
There are countless variables when choosing fishing spots, but simplifying our approach proved to be a huge advantage. We quickly decided to drop parameters like water temperature and salinity. Soon after, wind direction and strength were also removed, leaving us with a simplified data sheet:
- Date
- Catch
- Size of fish
- Water level
- Tide
- Strike depth: 0–30 cm, 30–60 cm, 60–100 cm, +100 cm
- Distance from shore: 0–5 m, 5–10 m, 10–15 m, +15 m
- Coast type: fjord or open coast
- Spot type: reef, trough, flats, soft/hard bottom
Fly choice was unrestricted. Since I tie most of my own flies, we often used similar patterns, each developing our own favorites. One fly stood out in particular—“Tangslaskeren”—which proved to be an exceptional fish-catcher. Sea trout from both Funen and the north coast of Zealand seemed to love this small, unassuming fly.
As the project progressed, things sometimes became almost absurd. We knew we were passionate anglers, but the extent to which it took over our lives was unexpected.
When you fish as much as we did, you occasionally enter a state where you feel completely connected to the coast and the fish. Among dedicated coastal anglers, we call it “being in the zone.” You know where, when, and how to fish—and the fish reward you with one great experience after another.
I remember unhooking and releasing yet another beautiful silver sea trout when my phone rang. It was Lars, excitedly describing his incredible morning. When he paused, I asked, “Weren’t you supposed to be at work today?” Silence… then laughter: “Yes—but I called in sick.” He asked where I was. “Of course, I’m on the coast too.”
Two grown men setting aside daily responsibilities for their passion says a lot about what coastal fishing means. By the end of the year, we had spent 242 days on the coast and caught 622 sea trout over 30 cm. This became the foundation for our analysis.
What were the most important findings during the study?
After 40 years of fishing the same spots, you naturally develop a sense of where the hotspots are. You accept that the coast is constantly changing—some spots shift quickly, others slowly. Driven by habit, I had fished these places in the same way for years. It worked—but now I was forced to approach them differently. The horizon had to wait. The shallow water came first. And that’s where I struck gold—or rather, silver.
It quickly became clear that my old spots held far more potential than I had realized. The innermost troughs and smallest reefs close to shore often held fish. To my surprise, many of my “blank days” disappeared because I could almost always find fish in shallow water—while deeper areas often produced nothing.
A key moment came early in the project. On a cold, windy day, Lars spotted a large shoal of fish very close to shore. When his #7 floating line landed, the reaction was immediate—panic. The entire shoal scattered.
We realized that our heavy lines were spooking fish—even at distances of 3–4 meters. Drawing on experience from bonefishing in the Bahamas, we adjusted: longer, thinner leaders and shorter casts. The results were immediate. Switching to lighter gear made an even bigger difference. With a #4 rod, the spooking stopped—and the catches increased. That same evening, Lars ordered a new #4 rod. We learned that lighter gear, shorter casts, and long leaders significantly reduce the risk of spooking fish in shallow water.
What did the final analysis reveal? Were there any major surprises?
There are far more sea trout in shallow water than I ever imagined. For a sea trout, “shallow” means 10–30 cm—ankle-deep water. Even white, foamy surf is not a problem—quite the opposite. By including shallow water in our fishing, I increased my catch rate by 35%. It’s almost frightening to think how many fish I had overlooked over the years.
Even large fish were present. The biggest fish of the project—a 77 cm sea trout—was caught in early March in a shallow coastal trough with less than 40 cm depth.
Catch distribution:
- 30–40 cm: 305 fish
- 40–50 cm: 223 fish
- 50–60 cm: 78 fish
- 60–70 cm: 14 fish
- 70–80 cm: 2 fish
85% of all fish were under 50 cm, which further justified using lighter gear.
Surprisingly, tide had little influence overall. With a 48/52% split between rising and falling tide, no clear conclusion could be drawn—though summer showed some patterns.
We also noticed that in winter, many fish were caught within 5 meters of shore—especially where depth quickly reached 40–50 cm. This likely relates to food sources like shrimp and amphipods concentrated in the surf zone.
How did the data compare with your prior experience?
While shallow-water fishing isn’t new, we were surprised by how overlooked it is. Confirming that a large proportion of sea trout stay in very shallow water during colder months is a true game changer. Instead of wasting time fishing deep water, anglers can move and search more effectively. We also challenged several dogmas about weather and conditions. Success depends more on being active and locating fish than on waiting for “perfect” conditions.
Interestingly, many fish still struck in less than 1 meter of water—even when we cast over deeper areas. Data showed that 60–80 cm depth is optimal in colder months, while deeper water becomes more important in summer.
What were the most important practical lessons?
The fishing spots I thought I knew turned out to hold much more potential. Focusing less on the horizon and more on the nearshore zone gave a deeper sense of connection—and better results. Conditions once considered poor—like strong onshore wind—became exciting opportunities.
Sea trout fishing doesn’t have to be physically demanding. With lighter gear and shorter casts, the focus shifts to technique and observation rather than distance.
Based on your findings, how can anglers best optimize their sea trout fishing?
A simple recipe for more sea trout:
- Use lighter rods (#3–5), with some backbone for wind
- Fish mainly with floating lines (intermediate only when needed)
- Use long nylon leaders (at least 12 ft), often 0.23 mm—or down to 0.18 mm on tough days
- Fish small, natural imitations (shrimp, gobies, amphipods)
- Focus on shallow water (under 1 meter)
- Keep casts short (under 20 meters)
Personally, I now use a #4 rod for 95% of my fishing.
After more than 40 years on the coast, I realize that if I had known then what I know now, I would have switched to lighter gear and shallow-water fishing much earlier.
I’m convinced the results would not only have been the same—but even better.
