How Overfishing Became a Conservation Strategy in Australia

Targeting an invasive sea urchin may be the key to saving Tasmania’s kelp forests

I remember the first time I saw a sea urchin barren. I was snorkeling on the Australian coast, where the water was cold but clear enough to see the devastation below. However, where there should have been kelp forests swaying with the current, there was only rock… bare and lifeless rock. 

Sea urchin barrens form when an overpopulation of sea urchins devours the kelp that once anchored an entire ecosystem. Without kelp, fish lose their shelter, invertebrates lose their food sources, and what was once a thriving underwater forest ecosystem turns into a rocky wasteland. 

As a scientist who has spent years studying ecosystems and conservation, I knew exactly what I was looking at: a marine desert, the direct result of an unchecked population of Longspined Sea Urchins.

These barrens aren’t just unsightly; they’re a sign of ecological imbalance. Without kelp, fish and invertebrates that rely on these forests for food and shelter disappear, and the commercial fisheries that depend on them, such as abalone and rock lobster, start to decline. 

For years, marine scientists and conservationists have struggled to solve the problem. But a new study suggests an unconventional solution: overfishing.

The study, led by Dr. Katherine Cresswell and her team at the University of Tasmania’s Institute for Marine and Antarctic Studies (IMAS), explores a paradoxical but effective strategy: intentionally overfishing the invasive Longspined Sea Urchin (Centrostephanus rodgersii) to restore balance to Tasmania’s marine ecosystems.

The idea of overfishing as a conservation tool might sound counterintuitive, but in this case, it makes sense. Hear me out. 

These urchins are not native to Tasmania, but arming waters have allowed their larvae, carried by the East Australian Current, to settle and thrive in areas that were previously too cold for them. 

Without natural predators (since that’s not their natural habitat), their populations have exploded, decimating kelp forests. The study investigates how a targeted commercial fishery, supported by government subsidies, can keep their numbers in check.

But how did they reach this conclusion? 

The researchers used population models to simulate different scenarios to understand whether commercial harvesting could work as a control measure. They compared areas where urchins were fished intensively to areas where they were left alone, estimating how the ecosystem would respond over time.

The results were quite telling: In regions where commercial harvesting was active, urchin densities had been reduced by up to 50%, and in some areas, kelp forests had even begun to recover. On the other hand, the study found that without fishing, the problem would be twice as bad, with barrens continuing to spread. 

More importantly, it showed that controlling urchin populations wasn’t just about removing them; it was about keeping densities below a critical threshold where they could no longer overgraze the kelp.

One of the key takeaways from the study is that commercial fishing alone won’t be enough unless it remains economically viable. That’s where government support comes in. 

Tasmania has implemented subsidies to incentivize urchin harvesting in critical areas. These subsidies ensure that divers keep removing urchins even when market demand fluctuates.

However, the goal is to make the urchin fishery profitable without subsidies in the long run. Urchin roe, what people eat from the urchin, also called “uni,” is a delicacy in many countries, and demand for high-quality, sustainably harvested roe is growing. 

If the industry can continue developing international markets and refining processing techniques, it could turn urchin control into a self-sustaining solution that doesn’t require external funds. A real nature-based solution.

Quite interestingly, the implications of this study extend beyond Tasmania. As climate change shifts species distributions, other regions will face similar challenges with invasive or range-extending species. In this context, traditional conservation tools, like marine protected areas or culling, may not always be practical. 

Instead, innovative solutions like this one, which align ecological goals with economic incentives, could offer a new way forward.

This research also challenges the traditional narrative that all fishing is harmful. In reality, well-managed fisheries can play a critical role in maintaining healthy ecosystems, especially when we harm well-established ecological balance. 

Overfishing, when strategically applied, can be a tool for resilience.

The success of Tasmania’s urchin fishery shows that conservation doesn’t always fit into neat categories. It’s not always about protecting species; it’s about protecting ecosystems. Sometimes, that means making difficult choices, like promoting overfishing for the sake of marine health.

However, for this approach to work in the long term, continued investment in monitoring, research, and market development will be essential. Without it, the gains made could quickly unravel, and Tasmania’s kelp forests could disappear entirely. However, if managed well, this strategy could serve as a model for other parts of the world facing similar ecological dilemmas.

Looking back at that dive site, I wonder what it would look like if these efforts succeeded. Maybe, in a few years, instead of barren rock, I’d see kelp forests making a comeback, fish darting through the fronds, and a healthier, more balanced ecosystem. 

That’s the hope, and with science-driven solutions like this, it’s a possibility worth fighting for.

Published in Fossils et al. Follow to learn more about Paleontology and Evolution.

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Best,

Sílvia P-M, PhD Climate Ages