Tackling the long spined sea urchin
The long spined sea urchin
(Centrostephanus rodgersii) has undergone range extension southwards from its native habitat in New South Wales over the past 40 years.
More recently, it has thrived in Tasmanian waters due to warming waters off the East Coast. Unchecked, the urchin’s presence is a risk to the ecological balance of the important Tasmania’s East Coast rocky reef ecosystems.
Long-spined sea urchins are now abundant from Eddystone Point to Fortescue Bay, with the current population estimated at around 20 million individuals.
The last IMAS survey in 2016/17 estimated that 15.2% of East Coast reef (4-40 m depth) was comprised of urchin barren. This is up from 3.4% in 2001/02.
By the end of 2022, in conjunction with partner organisations, the Department will unveil a multi-pronged strategy to mitigate the urchin’s impact.
Long-spined sea urchin strategy
A management strategy is being co-developed with CSIRO to provide a framework to apply controls in a targeted and measurable way for the benefit of community, environment, and fisheries. The three aims of the strategy are to:
- Stop new urchin barrens forming;
- Reduce growth of existing urchin barrens; and
- Reverse and rehabilitate existing urchin barrens.
Key partners will be engaged to control urchins:
commercial dive fishery: licensed commercial divers will be employed to harvest or cull urchin from ecologically and economically important areas.
recreational dive community: development of a program to support recreational and volunteer divers to protect recreationally important patches from urchin.
Other organisations with specialist skills and knowledge (like IMAS, CSIRO, and NRM South) to spearhead research, monitoring, and program delivery.
commercial dive fishery has been the primary means of controlling the urchins to date despite not being initially profitable. The introduction of a five-year subsidy paid to divers from the
Abalone Industry Reinvestment Fund between 2017 and 2022 saw a partnership between True South Seafood and IMAS unlock profitable markets with a viable fishery now operating.
As of June 2022, commercial divers have removed almost 2,400 tonnes of long-spined sea urchin.
Long spined sea urchin commercial catch by weight 2008-2022
The commercial dive sector has partnered with IMAS to facilitate ‘take-all’ harvests for research purposes to monitor recovery rates. They also have access to some declared fishery research areas to remove long-spined sea urchin only.
East Coast Rock Lobster Stock Rebuilding Strategy aims to rebuild lobster stocks to 20% by 2023 along the East Coast. Lobster are a known predator of long-spined sea urchin and their presence may assist to reduce the formation of barrens.
There are currently no bag or possession limits for recreational fishers.
In 2022, NRM South were commissioned to complete a feasibility study for a Volunteer Urchin Management Program.
IMAS have conducted long-spined sea urchin research for almost two decades. See their
sea urchin webpages for survey, harvesting and market development information including the 2020/2021 long-spined sea urchin
Experimental feed trials found that long-spined sea urchins are the least-preferred prey choice for lobster when native urchin species are available, and 85% were consumed by lobsters taken from urchin barrens who may have already been familiar with long-spined sea urchin as a food source.
Long-spined sea urchin stakeholder workshops have been convened by NRE Tas for two of the past three years. Further workshops are envisioned.
IMAS Long Spined Sea Urchin Research
Long Spined Sea Urchin Fishery Assessment
Invasive Sea Urchin population growth off Tasmania's East Coast - YouTube
Urchin Diving | TCDA - Vimeo
Who's been eating all the kelp? | IMAS - YouTube