2019 AIRF Funding Round

​​​​Decadal re-survey of long-term lobster experimental sites to inform Centrostephanus control

Lead Agency: Institute for Marine and Antarctic Studies (IMAS)
Funding: $30,000
Start Date: 1 September 2019                          End Date: 30 June 2021

Aims and Objectives:

The proposed project will re-survey baseline sites established during a previous Fisheries Research Development Corporation project (FRDC#2007/045) that investigated the effectiveness of rebuilding large lobsters to mitigate risk of urchin overgrazing.

Changes observed from 2008-2014 show decline in urchin abundance inside the dedicated no-take Fisheries Research Areas of Elephant Rock Research Reserve (ERRR) and North Bay Research Reserve (NBRR). From this prior research, the rebuilding of large predatory-capable lobster stocks within intact kelp beds (but containing incipient barrens) was, after 6 years, much more effective at reducing risk of barrens formation than was rebuilding of lobster stocks in an attempt to recover widespread barrens.

Given the research areas have remained in effect but have not been surveyed for the past 5 years, the re-survey of these experimental sites therefore presents an important opportunity to understand decadal trajectories in the capacity of large lobsters to mitigate the risk of sea urchin overgrazing.

The re-survey of these baseline sites constitutes highly cost-effective research to refine understanding of the effectiveness of lobster rebuilding strategies as an approach to control urchin overgrazing; thus, promoting sustainability of abalone stocks in eastern Tasmania.

Co-investment from IMAS will enable this objective to be achieved and will further enable a related objective regarding decadal trends in the ability of lobster stocks to be rebuilt on urchin barren grounds to be achieved, which will also contribute towards the overall effectiveness of 'east coast rock lobster stock rebuilding strategy' towards achieving ecological control of sea urchins.

Final Report:


  1. Lobster populations can be rebuilt on extensive Centrostephanus barrens providing lobster fishing is relaxed, however rebuilt lobster populations on extensive barrens (following complete closure to lobster fishing) did not control urchin populations within 12-yrs to the point where kelp could recover (previous modelling indicates >50-yrs for any control by lobsters on extensive barrens).
  2. Lobster populations can be rebuilt within kelp beds containing incipient barrens providing lobster fishing is relaxed, and following complete closure to lobster fishing, naturally high abundances of large lobsters can decrease urchin abundance and mitigate barrens expansion.
  3. To minimize the risk of barrens formation, the rebuilding of large-sized and abundant lobster populations within largely intact kelp beds should be prioritised.
  4. Alternative management interventions are required to rehabilitate extensive barrens in the near-term.


Aims: We conducted two simultaneous long-term (12-year) experiments to assess the effectiveness of rebuilding large predatory lobster populations (≥140 mm carapace length) to:

1) Recover kelp beds on extensive Centrostephanus barrens.
2) Prevent barrens formation in largely intact kelp beds with incipient Centrostephanus barrens.

Approach: Rebuilding of lobster populations occurred within designated research areas closed to lobster fishing, i.e. lobster-rebuilding ‘impact’ sites, encompassing (1) extensive barrens, and (2) kelp beds with incipient barrens. Lobster-rebuilding ’impact’ sites were closed to lobster fishing for 12-years following an initial accelerated rebuilding via translocation of ~1,000 large lobsters to each research area during the first year of closure to lobster fishing, representing the extreme case of possible lobster management options. For the extensive and incipient barrens experiments, monitoring of lobster, sea urchin and abalone populations, as well as barrens coverage, was performed ‘Before’ and ‘After’ lobster rebuilding for the ‘Impact’ and adjacent ‘Control’ sites open to fishing. An initial experimental set-up and intensive monitoring period of 3.5 years (from 2008 to 2011, i.e., FRDC Project #2007/045) indicated a rapid and encouraging decline in sea urchins inside at least one of the research areas (Johnson et al. 2013). This prompted continuation of the fisheries research areas for purposes of confirming early trends and to enable the effect of rebuilding lobster populations on urchin population dynamics to be established over a more ecologically meaningful timescale. Subsequently, given the ongoing nature of the fisheries research areas, an additional survey of the ‘impact’ and ‘control’ sites was achieved in 2014 and recently in 2020 (this project, funded by AIRF), enabling a 12-year assessment of the effectiveness of lobster rebuilding as a strategy for controlling Centrostephanus.

Results: We show that lobster population rebuilding, via closure of reefs to fishing, was achievable on both extensive and incipient urchin barrens reef. Notably, large resident lobsters (≥140mm carapace length) rapidly rebuilt such that after 3.5 years they were more numerous within closed areas than the ~1,000 large lobsters initially translocated to accelerate rebuilding. Relative to control sites, the lobster-rebuilding increased urchin predation potential within the research areas, yet after 12 years, no effect of the lobster-rebuilding was detected on extensive barrens. In contrast, lobster-rebuilding within largely intact kelp beds with incipient barrens had a significant effect in reducing Centrostephanus abundance and cover of incipient barrens relative to control sites. For the incipient barrens experiment, the native sea urchin Heliocidaris erythrogramma was also significantly reduced by the lobster-rebuilding relative to control populations. Further demonstrating that lobster-rebuilding can mitigate barrens-formation, the number of incipient barrens in the lobster-rebuilding research area was largely stable through time, while the abundance of barrens approximately doubled at the control sites over 12-years. The size of individually monitored incipient barrens patches also more than doubled, on average, whereas incipient barrens within the research area remained stable.

Results show that lobster-rebuilding will be more effective in preventing overgrazing in the first instance compared to attempts to recover kelp beds once extensive urchin barrens have formed. Notably, despite seven-years of the East Coast Rock Lobster Rebuilding Strategy, we report very low lobster CPUE at the control sites open to fishing, suggesting that intense localized fishing is countering broader rebuilding efforts across the coast. Low CPUE at these sites was particularly striking for large size-classes of lobsters that are capable of preying upon the dominant size-classes of urchins on the reefs. Proactive management for local-scale resilience of kelp beds against overgrazing, by rebuilding natural size and abundance of predatory lobsters, will be far more effective than reactive attempts to restore natural predators once collapse to extensive barren grounds has occurred. For managing extensive barrens, rebuilding natural predators will be ineffective for restoring kelp beds in the near-term noting that previous modelling indicated >50-yrs may be required for predatory lobsters to reduce urchins to the point of kelp recovery on extensive barrens (Johnson et al 2013).

Key findings: In summary, this long-term research demonstrates that “An ounce of prevention is worth a ton of cure” when it comes to controlling destructive overgrazing by Centrostephanus. That is, the longer time series obtained through this latest survey extends and consolidates the trends detected in previous research (Johnson et al. 2013). Confirming early-signals from the initial research, the rebuilding of lobsters as a control strategy for sea urchins must prioritise the rebuilding of lobster populations within largely intact kelp beds, which show early signs of barrens formation, before it is too late. To recover kelp beds on extensive barrens, much larger and costly management interventions will be required to ‘re-set’ productive kelp beds (e.g., urchin harvesting, culling and/ or quickliming). Providing kelp beds can be ultimately restored on extensive barrens, management of restored areas must explicitly focus on maximizing natural predators to ensure resilient and sustainable kelp bed ecosystems are maintained into the future.

  Decadal resuvey of long-term experimental sites to inform Centrostephanus control   (871Kb)

Centrostephanus Exhibition

Lead Agency: Institute for Marine and Antarctic Studies (IMAS)
Funding: $6,500
Start Date: 1 September 2019                          End Date: June 2021

Aims and Objectives:

This project is for a 3-month Centrostephanus exhibition in the public space at the IMAS Salamanca between Nov 2019 and Jan 2020.

The display will tell the story of the urchin problem in Tasmania and inform about control options. The exhibition will contain live urchins, photographic exhibition, public art, infoposters and brochures on impacts, video display of barrens and fishing, 360 VR setup.

There would also be launch and finale events which would include talks, urchin tastings, interactive displays, VR.


The Centro exhibit is primed and ready to go, with key components installed. It will run for 3 months once available to be opened to the public. In addition, there will be aquaria to show urchin barren and healthy reef, physical displays (urchin jaws, fishing equipment, waste products) and the 360 VR.

Resetting urchin barrens: liming as a rapid widespread urchin removal tool

Lead Agency: Institute for Marine and Antarctic Studies (IMAS)
Funding: $65,309
Start Date: 1 September 2019                          End Date: 30 March 2021

Aims and Objectives:

The aim of this preliminary liming project is to determine the effectiveness and feasibility of quicklime on Centrostephanus in Tasmania, and determine if large scale investment and field trials and application technology are warranted.


Longspined Sea Urchins were collected by divers from barren areas in Fortescue Bay, southeast Tasmania.  The urchins were transported to laboratory facilities at IMAS Taroona in 1000L seawater tanks to minimise handling and transport stress.  Animals were held and monitored for 14 days prior to experimental period to facilitate acclimation to laboratory conditions and enable elimination of individuals showing physical damage or stress from handling and transportation.

Experiments were conducted in 68 L plastic tanks, filled with sea water and flowthrough rates of ~2 l/min. Animals were exposed to quicklime treatments in individual application chambers for 3-5 min before being placed in their holding tank. Each treatment comprised of 16 individuals (4 individuals in each of 4 replicate tanks). Quicklime was distributed evenly through a 0.15 * 0.15 grid on the water surface (water depth of 0.3 m) above the urchin in the application chamber to ensure even application. Animals were monitored daily for a month after exposure, noting mortalities and/or lesions to the test. Replicate control tanks were also established for each experiment; there were zero mortalities in the control tanks.

Experiment 1 - determining optimal dosage and particulate size of quicklime to effectively kill urchins

The aim of experiment 1 was to determine both the optimal dosage and particulate size of quicklime to induce mortality on Centrostephanus rodgersii. A total of 144 urchins were subject to nine treatment types which had differing particulate size and dosage applications. Particulate sizes, obtained by sieving, were small (0.25 - 1 mm), medium (1 - 2 mm) and large (2 - 4 mm). Dosage rates were low (100 g/m2), medium (250 g/m2), high (400 g/m2) and were set based on dosages applied by Strand et al. (2020). Urchins selected during this experiment were of similar size; average test diameter (± SD) was 87 mm (± 9 mm).

Key Results
- The finer the quicklime particle the higher the mortality rate.
- Fine particles (0.25 - 1mm) at concentrations of 250 g/m2 and 400 g/m2 resulted in 100% mortality with 14 days.
- Fine particles (0.25 - 1mm) at a concentration of 150 g/m2 achieved 75% mortality after 30 days.
- Medium particles (1-2 mm) applied at 400 g/m2 resulted in 88% mortality after 30 days.
- Coarse particles (2-4 mm) applied at 400 g/m2 resulted in 44% mortality after 30 days.

Experiment 2 – Refining optimal Quicklime dosage with varying sea urchin size

The aim of experiment 2 was to refine Quicklime dosage concentrations from experiment 1 across a range of urchin sizes. Fine (0.25 - 1 mm) quicklime (Calcium Oxide) was applied at three concentrations (150 g/m2; 250 g/m2; 350 g/m2) across three size classes (small (56 ± 7 mm ), medium (84 ± 8 mm) and large (100 ± 10 mm)).

Key Results
- At lower dosages larger individuals had higher mortality rates.
- At higher dosages mortality occurred quicker in smaller individuals, but approached 100% across all size classes by 30 days.

Experiment 3 – Determining the potential harm caused to non-target species

The aim of experiment 3 will be to determine whether quicklime would cause harm to non-target species. Testing will be conducted on:
- Molluscs: abalone, periwinkle
- Echinoderms: sea cucumbers and feather stars native urchin
- Crustaceans: juvenile southern rock lobsters.

Trials are currently underway.

General observations and comments.

  • Finer particle size resulted in higher mortality.
  • Application rates need to be in excess of 250g/m2 (> 2.5 tonne per hectare) to induce mortality. A rate comparable to field trials in Norway (300g/m2; Strand, 2020).
  • Quicklime resulted in lesions, loss of spines and general weakness (inability to suction to tank), even if mortality never eventuated. In the wild this would make urchins more vulnerable to predation and further damage from exposure (swell), increasing mortality rates.
  • At a bulk cost of ~ $900/tonne, the cost of quicklime to treat a hectare of reef is $2,250. There may be increased cost to process quicklime to a consistent appropriate particle size – to be investigated.
  • It is possible that field application will be less efficient than that achieved in the laboratory, and higher application rates (and cost) may be required.
  • The biggest challenge moving forward is an engineering solution to apply quicklime at depth.

Commercial upscaling of urchin fertiliser

Lead Agency: Institute for Marine and Antarctic Studies (IMAS)
Funding: $538,580
State Date: 1 September 2019                          End Date: 31 August 2023

Aims and Objectives:

The aim of this project is to establish commercial processing of urchin waste, and test two key waste streams as an agricultural product on commercial crops; dried solids as a soil conditioner/fertiliser, and liquids to use as a foliar spray to enhance frost resistance.


A 5000 kg urchin waste processing machine was purchased from Liaoyang Nova Pharmaceutical Equipment Technology Co Ltd (China) in December 2019 by RTS PauaCo.  Prior to purchase, the then RTS PauaCo project manager Troy Cook travelled to China to ensure the plant met required specifications and make any necessary modifications.  The plant was shipped in July, cleared customs and arrived at RTS PauaCo in Electrona on the 25 August 2020.

Independent engineering consultants Pitt & Sherry have been engaged to review the plant and assist in plant commissioning. A site visit at Electrona will occur on 7 September to commence works.  The scope of work is:

  • Review of the offered system against the required performance characteristics, including production volume, processing times, production quality (biochemical and nutritional survival of components and future usefulness), energy usage and structural, mechanical and electrical requirements.
  • Focus on suggestions to modify or improve the system if needed in order to achieve the desired outcomes.
  • Assistance with commissioning and verification of the install to suit the client's needs and the equipment provider.

Modelling the fine-scale dispersal of Centrostephanus rodgersii larvae

Lead Agency: Institute for Marine and Antarctic Studies (IMAS)
Funding: $76,371
Start Date: 1 September 2019                          End Date: 30 December 2022

Aims and Objectives:

  • Construct a robust model (based on previous work of Sean Tracey) of larval dispersal for Centrostephanus rodgersii around the east coast of Tasmania using existing oceanographic data (piecing together highand low resolution)

  • Calculate the most likely sources for large recruitment events to the east coast of Tasmania

  • Predict whether the Tasmanian population may be self-recruiting or what oceanic changes may lead to self-recruitment

  • Set model up to be capable of addressing management decisions, such as which Tasmanian reefs would be most likely to produce larvae that survive the winter, which reefs pose the greatest risk of further range extension
  • The model could be flexible to allow input data for abalone or rock lobster larvae

Centro Cull The Southern Front

Lead Agency: Jeremy Huddlestone
Funding: $28,400
Start Date: 1 September 2019                          End Date: 31 October 2019

Aims and Objectives:
  1. Protect viable abalone Reef and habitat
  2. Stop the spread and expansion of centro
  3. Remove the centro from 22a where they are not yet plentiful enough to be commercially viable to harvest
  4. Establish a real cost to Urchin culling with the hope to roll out to other areas
Final Report

Key observations/recommendations:

  • Divers observed a substantial increase in Centro population in Munro Bight compared with that observed in the same area only 12 months ago.

  • Divers noted substantive weed, abalone and lobster recovery in shallow bottom previously affected by the June 2016 storm event.

  • Divers observed a “healthy” degree of recruitment of abalone populations within and around incipient Centro barrens.
  • Divers noted almost zero population of lobster, abalone or scale fish within the larger extensive Centro barrens. • A follow-up cull is recommended in abalone block 22a within 12 months.

  Final Report   (366Kb)

Centrostephanus Response Strategy

Lead Agency: CSIRO
Funding: $138,000
Start Date: 1 December 2019                          End Date: 15 September 2021

Aims and Objectives

The proposed centrostephanus response strategy will provide the formal instrument for guiding Centrostephanus management in Tasmania.  It may or may not be formally endorsed as a management plan under the Living Marine Resources Management Act 1995, but will guide State government response and inform and align with the response efforts of other governments, industry, researchers and communities in a manner similar to the Integrated Pest Management approach that underpins the Crown of Thorns Starfish strategy.

The strategy seeks to provide a comprehensive, integrated and action-oriented framework to achieve the following three strategic objectives:

  1. Stop growth of existing barrens;
  2. Prevent establishment of new barrens;
  3. Promote recovery of full barrens.

The strategy will address the full suite of potential management response options in the near and longer term.  It will bring together knoweldge, expertise and resources from a range of sources to address the threats posed by Centro.  It will emphasize the importance of results in the water that directly contribute to the strategic objectives.  The strategy would comprise the followng components:

  1. A review of existing knowledge;
  2. Reasonable and immediate management responses given the strategic objectives and the state of knowledge;
  3. Assessment of the feasibility of achieving stated objectives
  • Identification of the knowledge/ technology gaps that must be filled;
  • A medium-long term management and research strategy;
  • Identification of the knowledge/ technology gaps that must be filled;
  • Future control technologies

Key Considerations:

The strategy will consider, and to the extent feasible, address the following key dimensions of Centrostephanus management i) Biological and Ecological Dimensions, ii) social and economic dimensions, iii) management dimensions, iv) knowledge gaps.  These dimenstions and the assumptions underpinning them are considered more fully in the attachment.

Hit Them While They're Down 2020 Centro Cull

Lead Agency: Jeremy Huddlestone
Funding: $24,600
Start Date: 5 March 2020                          End Date: 31 May 2020

Aims and Objectives:

To cull areas of incipient barrens located but not culled last October. To extend range of cull, And to revisit gps location of previous Cull. Observe Seaweed and marine life recovery.

Final Report

Key project actions/outcomes:

  • 12 dive hours per dinghy was successfully completed over 3 days
  • Dives on previous sites revealed Seaweed and Abalone recovery, in all but one extremely cryptic area where urchins had returned to a est 50 percent of original population.
  • Seaweed is recovering quicker than expected, 1 area is recovering after only 5 weeks post a harvest Day
  • Harvest day completed in block 22a by Beau, Jeremy and Mic revealed a harvest rate of 140kgs per hour in a  specific non culled “virgin site" at a depth of 15-20meters
  • A total of 15100 Centro urchins were culled. Mostly in range extension areas
  • 30-40 percent of the Centro in Munroes Bight are below Market size

Key observations/recommendations:

  • Divers observed  almost night and day difference in original cull locations
  • Divers noted continued weed, abalone and lobster recovery in shallow bottom previously affected by the June 2016 storm event.
  • Divers observed a extremely “healthy" degree of recruitment of abalone populations within original cull sites and most productive areas of 22a
  • Divers noted almost zero population of lobster, abalone or scale fish within the larger extensive Centro barrens.
  • We believe additional culling and or harvesting will be required in this area particularity with the large number of small non marketable centros in the population .

Dive Specific Findings:

  • In this region, working depth is an important dive planning consideration. Divers were able to cull for up to 4.5 hours on the first day but as the trip went on, combined bottom time was a limiting factor in available dive time.
  • Moving to a 3 day cull was beneficial in managing crew fatigue and Dive profiles
  • Revised Crew renumeration of $1300 per diver per day and $500 per deckhand per day proved acceptable and the crew would be happy to participate on further projects on these rates
  • The crew was extremely buoyed by the recovery of productive abalone habitat, and abalone stocks are recovering extremely well, Whilst 22a is a work in progress we have made some large steps in returning this area into the fishery

Effects of Urchin fishing on Urchin populations and kelp recovery

Lead Agency: Institute for Marine and Antarctic Studies (IMAS)
Funding: $132,303
Start Date: 1 August 2020                          End Date: 30 August 2021

Aims and Objectives:

The overall aim of this project is to determine the impact of high intensity fishing pressure on urchin populations and the capacity of such pressures to restore kelp ecosystems on heavily fished reefs in NE Tasmania.

The specific objectives of this project are:

  • Assess changes in urchin population structure (urchin density, age and size) following high fishing pressure.
  • Quantify habitat (kelp recovery of reefs subjected to high fishing pressure.
  • Develop detailed spatial maps of urchin barrens in the greater St Helens region pre and post the 2018/19 period of high fishing intensity.
  • Assess the effectiveness of urchin fishing as an effective Centrostephanus control tool.

General comments from fieldwork observations (observational only, not validated).

Large extensive barrens still persist throughout the St Helens Region. In heavily fished areas small patches of kelp recovery are observed. However, in many heavily fished areas Centro abundance is still high and being maintained by the emergence of juveniles. In some areas the proportion of undersize (< 85 mm processing size) Centro is > 50%, compared to just 10-15% in virgin populations, while still maintain visually similar densities. While observationally it cannot be determined if there is an absolute change in barren percentage, patches of kelp regrowth and further decreases to the size structure are promising. On the deeper edge barrens may still be expanding. Video tows show that extensive barrens extend to the reef/sand edge (30-35 m) at many locations within the region.

​Task​Comments and Observations
- 12 30m*30m dive plots across Sloop Reef and Elephant Rock established 2014/16 to assess the effects of fishing to assess changes in urchin density and kelp cover in heavily fished and unfished regions.Completed
Observations: No large-scale changes evident. Areas of barren contraction may be offset by areas of barren expansion. Large numbers of juvenile urchins recruiting in some fished plots are maintaining barrens.
- 24 towed video transects from unfished areas at Ironhouse Point and Bicheno for control (unfished) sitesCompleted and extended to all 9 east coast sites – 50% of video processed
- 36 towed video transects from The Gardens, Sloop Reef, St Helens Island, previously completed as a part of state-wide surveys (2001/02 and 2016/17 - 12 transects) and Olivia Johnson’s Honours (2016 – 24 transects) to assess broadscale habitat recoveryCompleted
Deeper barren edge extending to sand edge on many transects.
- 12 dive transects (0-18m) across St Helen’s Island, St Helens Point and Elephant Rock previously surveyed in 2002 and 2017 as part of state-wide Centrostephanus surveys to assess changes in urchin density with depth and fishing pressure.Completed and data entered
- 300 urchins dissected from 6 sites between Sloop Reef and Paddy’s Island to assess changes in size and age structure (previously completed in 2016).Completed Size structure data entered and plotted. Age estimates underway. Continued declines in the size structure in heavily fished areas.
Additional - Kelp line video/GPS swims at Sloop rock and elephant rock.Completed – numerous patches of kelp regrowth observed along the kelp edge at Sloop Reef Rock, not evident at Elephant Rock with the closed area

Risk Profile for the paralytic shellfish toxins (PST) from Alexandrium cantenella in Tasmanian sea urchins

Lead Agency: Institute for Marine and Antarctic Studies (IMAS)
Funding: $92,110
Start Date: 1 July 2020                          End Date: 1 April 2023

Aims and Objectives:
  • Determine PST levels in two species of commercially harvested urchins on the east coast of Tasmania during blooms of PST producing algae
  • Complete a risk profile on PST accumulation in Heliocidaris erythrogramma and Centrostephanus rodgersii on the east coast of Tasmania as a result of A.catenella blooms to support public health and market access risk management activities.