Imagine spending years in a carefully managed environment designed to keep you alive, only to be released back into a home that has become increasingly difficult to survive in. That is the reality facing two endangered Maugean skates ( Zearaja maugeana ) which have just been returned to Tasmania’s Macquarie Harbour after more than two years in captivity. Their release should be a moment of celebration for the conservation world. Instead, it is more complicated than that.

That’s because the male and female skate were among four adults collected from Macquarie Harbour back in December 2023 by scientists from the Institute for Marine and Antarctic Studies at the University of Tasmania . The collection has been a part of an emergency captive-rearing program established after growing concerns that the species was edging dangerously close to extinction . Often described as a living relic, these animals belong to a lineage that has survived for millions of years. Today, however, its entire known population is restricted to a single location: Macquarie Harbour on Tasmania’s west coast. That kind of geographic restriction makes any species vulnerable because there is nowhere else to go. And in the case of the Maugean skate, the biggest problem is oxygen. Like all animals, skates need oxygen to survive. But in recent years, dissolved oxygen levels in parts of Macquarie Harbour have dropped to alarmingly low levels . Scientists have repeatedly linked low oxygen levels to intensive Atlantic salmon aquaculture in Macquarie Harbour. Yet the harbour’s oxygen cycle is also shaped by a complex interplay of natural and human-driven factors, including topography, tides, salinity, temperature, wind patterns, freshwater inflows and more than a century of changes across the surrounding catchment. As oxygen levels decline, suitable habitat for the skate (and other animals who call this area home) shrinks. These areas once supported feeding, movement and reproduction and for a species already living on the edge the consequences that come from their loss can be severe.

The captive-rearing program was designed as a safeguard against the worst-case scenario. Although two of the four collected adults died shortly after entering captivity, the surviving female produced about 400 eggs using sperm stored from five different wild males. So far, 79 hatchlings have survived in captivity, providing researchers with an unprecedented opportunity to learn about the species. Thanks to this process, scientists have gained insights into Maugean skate biology, behaviour and husbandry that were previously impossible to obtain in the wild because of how elusive these animals are, despite being confined to such a small space on Earth. Understanding how these animals grow, feed and respond to different environmental conditions will play a critical role in future recovery efforts. If that is possible in the future.

Successful captive programs as temporary bridges, not an end goal in this line of work. Their purpose is to buy time while threats in the wild are addressed. After all, no aquarium or zoo, no matter how sophisticated, can truly replace a functioning ecosystem. Which is what makes this release so bittersweet to Australian Marine Conservation Society shark scientist Dr. Leonardo Guida : “These skates deserved to be returned home to Macquarie Harbour, but Australians need to know these skates are leaving what was effectively a long-term spa retreat with oxygen-rich seawater to return to a significantly deteriorated harbour. We need a healthy harbour and, for that to happen, salmon farming must cease in Macquarie Harbour.”

Evidence suggests that Macquarie Harbour’s skate population is now dominated by adults, with many females approaching the end of their natural lifespan of around 10 to 12 years. Although juveniles have been detected, scientists worry that degraded environmental conditions may be preventing enough young skates from surviving long enough to reproduce. If that is happening, the species could slowly disappear through a process conservation biologists sometimes call “aging out.” In other words, even if adults remain present today, there may not be enough successful recruitment to sustain future generations.

Scientists have invested years of work into understanding and protecting the Maugean skate. Government funding has supported captive-rearing efforts. Researchers continue to monitor populations and investigate solutions. Yet conservationists argue that these efforts risk being undermined if the underlying drivers of habitat degradation are not addressed. The debate has become increasingly political, with tensions rising as conservation advocates have called for stronger actions to be implemented while the others stress that the salmon aquaculture remains an economically important industry in Tasmania. As Guida explains for the conservation side of the argument: “This species can still be saved, but only if we match scientific effort with political courage. Federal Environment Minister Murray Watt can immediately list Macquarie Harbour as critical habitat under our national nature laws, but if political will fails to remove salmon from the harbour, then consumers can discourage farming of Atlantic salmon in Macquarie Harbour by choosing not to buy it.” But it doesn’t answer the questions that arise if Australia removes salmon farming from Macquarie Harbour, like, what happens to the workers, families and communities that rely on the industry? How do we weigh the survival of a species found nowhere else on Earth against the economic realities facing the people who live alongside it? How much effort should be invested in saving a species if we are unwilling to address the conditions pushing it toward extinction?

These are not questions unique to Tasmania. Around the world, conservation programs are increasingly relying on captive breeding, assisted reproduction and other technological interventions to prevent extinctions (in the shark world, one of the most famous efforts is ReShark ). Such tools can be remarkably effective, as has been seen in the ReShark initiative! But they often work best when paired with habitat protection rather than used as substitutes for it.

For now, the Maugean skate has been given another chance. Whether that chance is enough may depend less on what happens inside research facilities and more on what happens in the waters of Macquarie Harbour itself. As Guida says: “The clock isn’t just ticking for the Maugean skate; it’s running out.”