Long-spined sea urchins (Centrostephanus rodgersii) have invaded Tasmania and Victoria from their historical range in New South Wales. Where it occurs, this species dominates near-shore reefs to create "barrens habitat." This is where at high densities sea urchins remove all large brown algae (kelp), and few abalone and other important species for fishers remain.

Both climate change and over-fishing of its main predators have been blamed for the urchin's southward extension.

This is a central issue in the ongoing Senate inquiry into climate-related marine invasive species, which has brought the challenges and contradictions of managing the marine estate into sharp relief. The inquiry received over 40 diverse and often contradictory submissions.

It's clear there is little national consensus about the nature of the sea urchin problem, its causes, or what to do about it. In Tasmania and Victoria, policy directions are clear and being implemented. But managing barrens within New South Wales seascapes isn't as clear cut. Although a single solution may not be clear now, there is a path forward.

Meet the long-spined sea urchin

Long-spined sea urchins defend themselves with a menacing armory of long, hollow spines. By day they are found in crevices or aggregated on the reef, and emerge to forage at night. As with many sea urchins, their roe (unfertilized fish eggs and sperm) is edible and the species is harvested in all three southeastern states.