Acoustic Tags Track Alaska’s King Salmon Decline

Alaska — A groundbreaking exploration design led by scientists from the University of Alaska Fairbanks (UAF) and the Alaska Department of Fish and Game (ADFG) is seeking to unravel one of the state’s most pressing ecological mystifications—the decline of the iconic king salmon. Using slice-edge aural trailing technology, experimenters hope to uncover what happens to youthful king salmon as they transition from brackish aqueducts to the open ocean—a critical and dangerous stage in their life cycle. The design focuses on juvenile king salmon, known as smolt, during their migration from the Kenai River to Cook Inlet. The Kenai River, long celebrated for its world-famed king salmon runs, has become a symbol of the species’ struggles amid wide declines across Alaska. Experimenters believe that understanding the challenges faced by salmon during their early ocean trip could hold the key to reversing their population collapse. Andy Seitz, a professor at the UAF College of Fisheries and Ocean Sciences and co-leader of the design, explained that the smolt stage is a particularly vulnerable period for king salmon. “It’s a time when they’re going through physiological changes, and it’s also a dangerous stage,” Seitz said. “They’re changing from brackish to saltwater fish, and there are a lot of empty mouths in the ocean.” For decades, utmost exploration efforts have concentrated on adult king salmon—their migration routes, spawning geste, and crop patterns. Still, the early life stages of these fish have remained inadequately understood. This new study aims to bridge that knowledge gap by tracking the youthful salmon as they make the pivotal transition into the marine terrain. Over the summer, the exploration platoon completed the design’s first field season, implanting 289 juvenile king salmon from the Kenai River with small aural markers. Each label, roughly the size of a Tic Tac mint, emits a unique signal or “clunk” that can be detected by aquatic hydrophones strategically placed along the swash and near its mouth. These signals allow scientists to identify individual fish and track their movements in real time as they resettle downstream toward Cook Inlet. One of the most significant installations in the design is a 4-afar-wide array of hydrophones located near the mouth of the Kenai River. This network of receivers acts as a harkening hedge, detecting the tagged fish as they pass through this critical zone. According to Seitz, this array will be doubled in size in the coming field season to expand the monitoring range and ameliorate data delicacy. “We’re learning how to acclimatize this technology to the rugged Kenai River terrain,” he said, emphasizing that this is the first time similar aural styles have been used to study juvenile salmon in Alaska. The original season of the design was devoted to enriching the technology and ensuring that the outfit could repel the wash’s strong currents, variable runs, and deposition-heavy waters. Graduate scholars from UAF’s College of Fisheries and Ocean Sciences, including Johnna Elkins, Dakota Rygh, and Danielle Tryon, played a central part in this trouble. Both Elkins and Tryon, who also work for ADFG, contributed to fieldwork and data collection during the summer, installing receivers and tagging fish. The collaboration between UAF and ADFG combines academic exploration with on-the-ground fisheries operation moxie. Together, the brigades hope to identify the “survival backups” that help numerous youthful salmon from reaching maturity. These backups could include predation, changes in water temperature, niche declination, or shifts in ocean conditions caused by climate change. Tony Eskelin, a fisheries biologist with ADFG grounded in Soldotna and the design’s lead for the department, emphasized the significance of this phase in the salmon’s life cycle. “Transitioning into the marine terrain is a dangerous life stage for these fish,” Eskelin said. However, perhaps we can make some opinions to help them along the way: “If we can better understand factors affecting their survival.” He added that the platoon has gathered a substantial quantum of data that will take months to dissect, but the perceptivity gained could impact unborn operation opinions for king salmon populations across Alaska. The design, funded by a $4 million civil contract through the National Oceanic and Atmospheric Administration (NOAA), will continue for at least two further summers. The extended timeline will allow experimenters to collect multi-year data, track survival patterns, and study how different environmental factors—such as temperature shifts or changes in swash inflow—influence smolt success. For Alaska, where king salmon hold both artistic and profitable significance, the stakes are high. Declining salmon runs have affected subsistence fishermen, sport fishing diligence, and original communities that depend on these fish for food and livelihoods. Understanding what happens to salmon during their foremost ocean migrations could give vital suggestions for reversing these declines. Seitz believes that the innovative use of aural trailing represents a promising step forward for fisheries wisdom. “We’ve a lot of excitement for this design, and a lot of data to reuse,” he said. “The further we learn about these fish at this vulnerable stage, the better we can cover them throughout their life cycle.” As the exploration continues, the scientists hope that their findings will inform further effective conservation strategies—not just for Alaska’s king salmon, but for salmon populations across the North Pacific. By combining new technology with cooperative exploration, the design aims to exfoliate light on one of the most mysterious and critical stages in the life of these remarkable fish. In the coming times, as data accumulates and further salmon are tracked, the experimenters anticipate gaining unknown sapience into where and why youthful salmon corrupt during their migration. Those answers could eventually help restore Alaska’s king salmon runs to their former strength—icing that these fabulous fish continue to thrive in the state’s gutters and abysses for generations to come.