*

Over recent decades, the Longspined Sea Urchin has extended its range southwards to VIC and TAS, reflecting the increasing influence of the south-flowing Eastern Australian Current in those latitudes. At high densities, Longspined Sea Urchins can damage kelp habitats through overgrazing, leading some jurisdictions to pursue urchin removal programs. Longspined Sea Urchin stock structure is uncertain and management arrangements differ across jurisdictions, so this assessment is presented at the jurisdictional level. Longspined Sea Urchin are classified as sustainable in NSW, TAS and VIC.

Within its historic endemic distribution along the central east coast of Australia, the Longspined Sea Urchin, Centrostephanus rodgersii, inhabits coastal reefs in habitats consisting of a mosaic of foliose and turfing algae, typically in relatively shallow water (less than approximately15 m depth). In these areas, Lonspined Sea Urchin grazing can create and maintain habitats devoid of foliose algae and dominated by crustose coraline algae-covered rock, commonly termed ‘barrens’ [Underwood et al. 1991]. Within this historic range and over the 30 years to 2020, Glasby and Gibson [2020] estimated that there had been relatively small changes in the aerial extent of barrens, with some sites showing very little change or a reduction in extent. Densities of Longspined Sea Urchins are typically lower in nearshore mosaic habitats than in barrens [Blount 2004; Ling et al. 2009], likely a reponse to food supply [Ling and Johnson 2009]. In contrast, age structures appear similar between habitats, with evidence indicating no difference in the longevity of Longspined Sea Urchins between fringing and barrens habitats [Blount et al. 2024]. 

Over the last several decades the Longspined Sea Urchin has undergone a range extension to Victoria and Tasmania from NSW due to extensions in the warm East Australia Current brought about by climate change and modulated by larval thermal tolerance limits [Johnson et al. 2005; Ridgway 2007; Ling 2008; Byrne et al. 2022]. This southerly movement is likely to continue, accompanied by density reductions in northern parts of the range [Davis et al. 2023].

The strength of connectivity between regions and the species' capacity for self-recruitment at the extremes of its distribution remain poorly understood and are currently under investigation as part of an FRDC project 'Larval dispersal for Southern Rock Lobster and Longspined Sea Urchin to support management decisions.

Understanding Longspined Sea Urchin population structure has been of particular importance as high urchin densities can damage kelp forests through overgrazing [Ling et al. 2009; Johnson et al. 2011; Marzloff et al. 2016], and this has resulted in notable habitat changes in areas of range extension. Due to this impact and the range-extending nature of this species, management measures are being actively pursued to decrease the population density in some jurisdictions.

 Due to limited knowledge regarding stock structure and different jurisdictional management objectives this species is assessed here at the jurisdictional level—New South Wales, Tasmania and Victoria.

New South Wales

Longspined Sea Urchins are endemic to NSW coastal reefs, where they are the dominant herbivore and an important component of rocky reef ecosystems [Przeslawski 2023]. They are also the primary targeted species of the NSW Sea Urchin and Turban Shell (SUTS) Fishery and there is a relatively small recreational fishery. Longspined Sea Urchins are commercially harvested in NSW throughout their latitudinal distribution, from the subtropical northern coastal regions to the temperate southern NSW–Victorian border. Only fishers with a SUTS Fishery licence can commercially harvest SUTS Fishery defined species, including the Longspined Sea Urchin, with harvest restricted to hand collection and/or the use of a basic tool or ‘hook’, resulting in no by-catch or by-product harvest. Longspined Sea Urchin are harvested for their roe, the condition of which is influenced by their seasonal reproductive stage (typically harvested from late summer to autumn), food quantity and quality [Byrne et al. 1998] and density [Blount et al. 2017]. Urchins located in the nearshore mosaic of foliose and turfing algal habitats produce roe of marketable quality, whereas those in barrens have poor quality or no roe. However, reducing the density of urchins or moving them from barrens to fringe can result in the production of quality roe [Blount et al. 2017]. 

Commercial catches were relatively stable, averaging 50 tonnes (t) per year, from 2000 to 2011 (range 24–68 t per year) and has generally increased, to 86 t per year between 2012 and 2022 (range 67–129 t per year) [Chick 2022]. During 2018–19, the NSW recreational fishery retained harvest estimates for all sea urchins was about 1 t (approximately 2,400 individuals) [Murphy et al. 2020], the majority of which are considered Longspined Sea Urchin. No recreational catch estimates for sea urchins are available from the more recent state-wide survey [Murphy et al. 2022] or previous state and national recreational fishing surveys, with sea urchins either not having been reported [West et al. 2015] or included into a species reporting group ‘other’ along with various other ‘non-fish’ species [Henry and Lyle 2003].

Fishery-independent surveys of the density and size structure (test diameter and weight) of Longspined Sea Urchins, in nearshore mosaic and barrens habitat and calculations of the area of these habitats (out to 100 m from shore) were completed in NSW in 2000 [Worthington and Blount 2003]. This study estimated the biomass of Longspined Sea Urchins in fringe habitat was estimated at about 20,000 t. This biomass estimate was considered close to unexploited levels due to limited fishing prior to 2000. Deterministic estimates indicated that catching 1-5% of the unexploited biomass would produce Maximum Sustainable Yield (MSY). Annual catches of 200–1,000 t were therefore considered sustainable, independent of the population of Longspined Sea Urchins in barrens (estimated at about 30,000 t) [Worthington and Blount 2003]. 

Andrew et al. [1998] also surveyed the density and size structure of Longspined Sea Urchin in barrens and the extent of barrens along NSW coastal areas. Results from that study indicated no substantial change in barrens habitat compared with surveys at some similar locations done in 1988 [Underwood et al. 1991]. Moreover, Glasby and Gibson [2020] describe decadal patterns of change in areas of barrens in NSW, concluding that 55% of sites investigated had either no change or fluctuations (±10%) in area of barrens. In the remaining 45% of study locations, barrens area had increased on average approximately 20 m² per hectare of reef per year but with considerable variability among sites [Glasby and Gibson 2020]. There were no differences in the dynamics of barren habitat through time along a longitudinal gradient [Glasby and Gibson 2020]. 

Biomass estimates of Longspined Sea Urchin from NSW coastal reefs in 2000, together with consistent, relatively low levels of commercial harvest distributed throughout the state (below estimates of MSY), low levels of recreational catch and relative long-term stability in areas of habitat supporting Longspined Sea Urchins suggest that the biomass of this stock is unlikely to be depleted and that recruitment is unlikely to be impaired. The above evidence also indicates that the current level of fishing mortality is unlikely to cause the stock to become recruitment impaired.  

On the basis of the evidence provided above, Longspined Sea Urchin in New South Wales is classified as a sustainable stock.

.

Distribution of reported commercial catch of Longspined Sea Urchin.

New South Wales – Indigenous (Management Methods). https://www.dpi.nsw.gov.au/fishing/aboriginal-fishing

Victoria – Indigenous (Management Methods). A person who identifies as Aboriginal or Torres Strait Islander is exempt from the need to obtain a Victorian recreational fishing licence, provided they comply with all other rules that apply to recreational fishers, including rules on equipment, catch limits, size limits and restricted areas. Traditional (non-commercial) fishing activities that are carried out by members of a traditional owner group entity under an agreement pursuant to Victoria’s Traditional Owner Settlement Act 2010 are also exempt from the need to hold a recreational fishing licence, subject to any conditions outlined in the agreement. Native title holders are also exempt from the need to obtain a recreational fishinglicence under the provisions of the Commonwealth’s Native Title Act 1993.

Tasmania - Living Marine Resources Management Act 1995. https://www.legislation.tas.gov.au/view/html/inforce/current/act-1995-025

Commercial catch of Longspined Sea Urchin - note confidential catch not shown.

1. Andrew, NL, Worthington, DG, Brett, PA, Bentley, N, Chick, RC and Blount, C 1998, Interactions between the abalone fishery and sea urchins in New South Wales. NSW Fisheries Research Institute. Cronulla, Australia. Fisheries Research and Development Corporation Project No. 93/102. NSW Fisheries Final Report Series No.12. ISN 1440-3544.
2. Bell, JD, Ingram, BA, Gorfine, HK and Conron, SD 2023, Review of key Victorian fish stocks — 2022, Victorian Fisheries Authority Science Report Series No. 38, First Edition, June 2023. VFA: Queenscliff. 105pp.
3. Blount, C 2004, Density-dependent aspects of the ecology of the sea urchin Centrostephanus rodgersii. PhD Thesis, University of Sydney, Sydney, NSW, Australia.
4. Blount, C, Chick, RC and Worthington, DG 2017, Enhancement of an underexploited fishery – Improving the yield and colour of roe in the sea urchin Centrostephanus rodgersii by reducing density or transplanting individuals. Fisheries Research 186, 586-597.
5. Blount, C, Worthington, DG, Byrne, M, Chick, RC and Andrew, NL 2024, Aging of the sea urchin Centrostephanus rodgersii using demi-pyramid. Fisheries Research 270 (106899).
6. Byrne, M and Andrew, N 2020, Centrostephanus rodgersii and C. tenuispina. In: Lawrence, J (Ed.) Sea Urchins: Biology and Ecology, Elsevier B.V. California. 281–297.
7. Byrne, M, Andrew, NL, Worthington, DG and Brett, PA 1998, Reproduction in the diadematoid sea urchin Centrostephanus rodgersii in contrasting habitats along the coast of New South Wales, Australia. Marine Biology 132, 305-318.
8. Byrne, M, Gall, ML, Campbell, H, Lamare, MD and Holmes, SP 2022, Staying in place and moving in space: contrasting larval thermal sensitivity explains distributional changes of sympatric sea urchin species to habitat warming. Global Change Biology 28: 3040–3053.
9. Chick, RC 2022, Fishery statistics summary 2022 – Sea Urchin and Turban Shell Fishery – Red Sea Urchin (Heliocidaris tuberculata). NSW Department of Primary Industries. Fisheries NSW, Port Stephens Fisheries Institute: 19 pp.
10. Chick, RC 2022, Fishery statistics summary 2022—Sea Urchin and Turban Shell Fishery – Red Sea Urchin (Heliocidaris tuberculata). NSW Department of Primary Industries. Fisheries NSW, Port Stephens Fisheries Institute: 19 pp.
11. Cresswell, K, Hartmann, K, Gardner, C and Keane, J 2023, Tasmanian Longspined sea urchin fishery assessment 2021/22
12. Cresswell, KA, Keane, JP, Ogier, E and Yamazaki, S 2019, Centrostephanus subsidy program: initial evaluation. Institute for Marine and Antarctic Studies, University of Tasmania, Hobart, Tasmania.
13. Davis, T., Knott, N., Champion, C., Przeslawski, R 2023, Impacts of Climate Change on Densities of the Urchin Centrostephanus rodgersii Vary among Marine Regions in Eastern Australia. https://doi.org/10.3390/d15030419
14. Edgar, GJ and Barrett, NS 1997, Short term monitoring of biotic change in Tasmanian marine reserves. Journal of Experimental Marine Biology and Ecology 213:261-279
15. Glasby, TM and Gibson, PT 2020, Decadal dynamics of subtidal barrens habitat. Marine Environmental Research 154, https://doi.org/10.1016/j.marenvres.2019.104869
16. Henry, GW and Lyle JM 2003, The National Recreational and Indigenous Fishing Survey. Tasmanian Aquaculture and Fisheries Institute, Hobart. FRDC 99/158.
17. Johnson, CR, Banks, SC, Barrett, NS, Cazassus, F, Dunstan, PK, Edgar, GJ, Frusher, SD, Gardner, C, Haddon, M, Helidoniotis, F, Hill, KL, Holbrook, NJ, Hosie, GW, Last, PR, Ling, SD, Melbourne-Thomas, J, Miller, K, Pecl, GT, Richardson, AJ, Ridgway, KR, Rintoul, SR, Ritz, DA, Ross, DJ, Sanderson, JC, Shepherd, SA, Slotvvinski, A, Swadling, KM and Taw, N 2011, Climate change cascades: Shifts in oceanography, species' ranges and subtidal marine community dynamics in eastern Tasmania. Journal of Experimental Marine Biology and Ecology 400:17-32.
18. Johnson, CR., Ling, SD, Ross, J, Shepherd, S and Miller, K 2005, Establishment of the longspined sea urchin (Centrostephanus rodgersii) in Tasmania: first assessment of potential threats to fisheries. Fisheries Research and Development Corporation
19. Ling, SD 2008, Range expansion of a habitat-modifying species leads to loss of taxonomic diversity: a new and impoverished reef state. Oecologia 156:883-894.
20. Ling, SD and Keane, JP 2018, Resurvey of Longspined sea urchin (Centrostephanus rodgersii) and associated barren reef in Tasmania. Hobart.
21. Ling, SD, Johnson, CR 2009, Population dynamics of an ecologically important range-extender. Marine Ecology Progress Series 374, 113–125. doi:10.3354/meps07729
22. Ling, SD, Johnson, CR, Frusher, SD and Ridgway KR 2009, Overfishing reduces resilience of kelp beds to climate-driven catastrophic phase shift. Proceedings of the National Academy of Sciences of the United States of America 106:22341-22345.
23. Marzloff, MP, Little, LR and Johnson, CR 2016, Building Resilience Against Climate Driven Shifts in a Temperate Reef System: Staying Away from Context-Dependent Ecological Thresholds. Ecosystems 19:1-15.
24. Murphy, JJ, Ochwada-Doyle, FA, West, LD, Stark, KE and Hughes, JM, 2020, The NSW Recreational Fisheries Monitoring Program - survey of recreational fishing, 2017/18. NSW DPI - Fisheries Final Report Series No. 158.
25. Murphy, JJ, Ochwada-Doyle, FA, West, LD, Stark, KE, Hughes, JM and Taylor, MD 2022, Survey of recreational fishing in NSW, 2019/20 – Key Results. NSW DPI – Fisheries Final Report Series No. 161. ISSN 2204-8669.
26. Przeslawski, R, Chick, R, Day, J, Glasby, T and Knott, N 2023, Research Summary – New South Wales Barrens. NSW Department of Primary Industries.
27. Ridgway, KR 2007, Long-term trend and decadal variability of the southward penetration of the East Australian Current. Geophysical Research Letters 34
28. Underwood, AJ, Kingsford, MJ and Andrew, NL 1991, Patterns in shallow subtidal marine assemblages along the coast of New South Wales. Aust. J. Ecol. 16: 231-249.
29. VFA 2019, Spatial and temporal trends in the abundance of long-spined sea urchins (Centrostephanus rodgersii) in Eastern Victoria using available fishery and fishery independent information. Victorian Fisheries Authority Science Report Series No. 10.
30. West, LD, Stark, KE, Murphy, JJ, Lyle JM and Doyle, FA 2015, Survey of recreational fishing in New South Wales and the ACT, 2013/14. Fisheries Final Report Series No. 149.
31. Worthington, DG and Blount, C 2003, Research to develop and manage the sea urchin fisheries of NSW and eastern Victoria. FRDC Project No. 1999/128. NSW Fisheries Final Report Series No. 56. ISSN 1440-3544.