Data from the Institute for Marine and Antarctic Studies (IMAS) has supported size limit increases and catch caps to ensure sea urchin aficionados can enjoy this unique delicacy for years to come.

Unlike Longspined Sea Urchins (Centrostephanus rodgersii), a highly over abundant species, there was little data on Shortspined Sea Urchins (Heliocidaris erythrogramma), a Tasmanian native and a unique delicacy.

In recent years, increasing concern surrounding Longspined Sea Urchins and rapidly expanding urchin barrens prompted governments and sector bodies to incentivise the catch of these prickly characters.

This unfortunately had the unintended consequence of increasing fishing pressures on Shortspined Sea Urchins.

To ensure the sustainability of Shortspined Sea Urchins, FRDC supported the Institute for Marine and Antarctic Studies (IMAS) to undertake robust science to underpin the management of this species (FRDC Project 2017-033).

Project lead Dr John Keane says that clear size limits for Shortspined Sea Urchins whilst increasing catch limits for Longspined Sea Urchins was vital. 

“When we started compiling information on growth and maturity early in the project, we realised there were a lot of small urchins in the harvest,” John says.

“It was obvious that the size limits were too small to protect the population from over-fishing and we know demand in local and global markets for premium uni (sea urchin roe) is high.” 

This led John and his team to develop a customised electronic sea urchin measuring board for on-vessel research and processing facilities.

“The way we were doing it before was a two-person operation and once we developed the tech, it took it down to a one-person operation,” John says.

“The measuring board automatically records the data, so there's no writing down of anything. It’s vastly improved efficiency and productivity.”

The project also saw the legal minimum size of Shortspined Sea Urchins increase from 60 mm to 80 mm.

“By increasing the minimum size, it preserves the reproductive potential of the stock as this size is reached 3 years after they reach sexual maturity,” John says.

Another interesting piece of data, which has helped implement catch caps in key harvest regions, is the small larval dispersal of Shortspined Sea Urchins.

“Their larval duration is short, only about three to five days. So, they're only floating around in the ocean for this time,” John explains.

“Because the dispersal is small, you need small scale management. Our research on population connectivity supported the introduction of catch caps in areas from St Helens, all the way down to the Derwent River.

“This minimises the chance of localised depletion.”

Supporting an enduring sea urchin industry

The results of this study were made easy to implement by the government as sea urchin divers, represented by the Tasmanian Commercial Divers Association (TCDA), have shown strong stewardship in the way they approach resource sustainability. 

“The TCDA proactively support management practices that will protect the long-term health of the resource, recognising that their livelihoods depend on maintaining healthy stocks,” John says. 

“Their commitment ensures that harvesting is carried out sustainably, with future generations of divers in mind.

Related FRDC Project

2017-033: Fisheries biology of short-spined sea urchins (Heliocidaris erythrogramma) in Tasmania: supporting a profitable harvest and appropriate management