The first time the net came up from the inky depths, it was just before sunrise. The deck lights flickered against a grey horizon, and the crew expected the usual mix of mud, broken shells, and the occasional discarded fish. Instead, the net pulsed with hundresd of tiny bodies with glowing bellies, large eyes built for darkness staring back at them. Their skin was marked by faint bioluminescent patterns that looked like scattered constellations.

These were no regular fish. These were velvet belly lanternsharks.

For years, this species (scientifically known as Etmopterus spinax ) has sat in a scientific blind spot in the Adriatic Sea. Occasional records, often decades apart, painted a picture of scarcity — a deep-water passerby, if you will. But between 2023 and 2025, a fisheries-dependent monitoring program off Vlorë, Albania began to fill in that gap. Over 319 individuals of Etmopterus spinax were recorded from bottom trawlers and longlines operating between 1,476 and 2,133 feet (450 and 650 meters) depth and appeared consistently across hauls deeper than 1,640 ft (500 m), sometimes in single catches of more than 50 animals! Among them? Neonates, juveniles, and gravid females which suggests that parts of the Adriatic continental slope may function as a nursery area.

Yes, a species that was once thought to be a mere visitor seems to call the area “home,” with their young pups beginning their lives in deep, cold, dimly lit waters that most of us will never see. It’s an exciting find for shark science, as deep-sea species like lanternsharks grow slowly, mature late and produce relatively few offspring. These are life strategies built for stability, but those same life histories become their biggest vulnerability when industrial fishing expands into deeper waters. Afterall, a population that cannot rebound quickly is a population that can disappear quietly. So one of the most striking findings from this study was the difference in survival depending on fishing gear. Sharks caught in bottom trawls experienced 100 percent mortality by the time they reached the vessel but those caught on longlines, however, were sometimes still alive when brought aboard. That difference may sound like just a technicality, but it suggests that how we fish is just as important as how much we fish, especially in deep ecosystems where recovery is slow and data is limited.

The researchers also used DNA analysis of mitochondrial COI sequences to reveal moderate diversity and six previously unrecorded haplotypes. Basically, these sharks are not genetically uniform and while the Adriatic population appears partially isolated, it seems to be shaped by both movement and restriction. So what does it mean when a species long assumed to be rare turns out to be consistently present, reproductively active and genetically distinct at a regional scale? It means our baseline assumptions may be off — and that deep-sea fisheries are interacting with ecosystems we are only just beginning to map in biological detail. If the upper Adriatic slope is functioning as a nursery for velvet belly lanternsharks, then it may also be important for other deep-sea species with similarly slow life histories.

The fact of the matter is that our deep-sea fisheries are not operating in a fully known system. We are operating in a system where the map is still being drawn while extraction is already underway, with bottom trawls and longlines pillaging these out-of-sight ecosystems before baseline ecological understanding exists. We are removing biomass from systems that are still being defined in real time. We are applying industrial pressure to populations whose connectivity, reproductive hubs, and spatial dependencies are only now being inferred through studies like this one. By the time declines are recognized, the ecosystem has already shifted, and we are left trying to reconstruct what “normal” looked like from fragmented records and degraded signals. In a shallow-water fishery, you might have decades of observations to work with. In the deep sea? You often have sporadic encounters, opportunistic sampling, and long periods of silence that can mask either stability or collapse.

Whether we want to admit it out loud or not, deep-sea management is still often built on the assumption that low visibility equals low vulnerability. If the upper Adriatic slope is functioning as a nursery, then it is a life-support structure for a broader ecological network. And if that is true, then the impact of disturbance is not localized to what is caught in a net but extends outward through recruitment failure, reduced genetic exchange, and the gradual erosion of population structure we may not detect until it has already flattened. There are a lot of questions that come from this discovery, but right now, we just have 319 sharks that are acting as clear, measurable, repeatable evidence that life in the deep Adriatic is more present and more vulnerable than previously assumed.