*

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.

Over the last several decades the Longspined Sea Urchin, Centrostephanus rodgersii, 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 [Johnson et al. 2005, Ridgway 2007, Ling 2008].

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 a targeted species within the Sea Urchin and Turban Shell (SUTS) Fishery and there is a relatively small recreational fishery. Only fishers with a SUTS Fishery licence can commercially harvest SUTS Fishery defined species, including the Longspined Sea Urchin. Divers harvest Longspined Sea Urchins, together with other SUTS Fishery species by hand, or with the use of a ‘hook’, resulting in no by-catch or byproduct. Longspined Sea Urchins are commercially harvested throughout their latitudinal distribution, from the subtropical northern coastal regions of NSW to the temperate southern NSW – Victorian border. They are harvested for their roe, the condition of which is influenced by their seasonal reproductive stage (typically harvested from late summer to autumn) and food quantity and quality [Byrne et al. 1998]. Urchins located in fringe (macro-algal covered reef) habitat produce roe of marketable quality, whereas those in barrens (crustose coraline algae covered ‘bare rock’) have poor quality or no roe. However, reducing the density of urchins or moving them from barrens to fringe will result in the production of quality roe [Blount et al. 2017]. 

Commercial catches have been relatively stable, averaging 67 tonnes (t) per annum since 2009–10 (range 34–108 t p.a.) [NSW DPI, unpublished data]. During 2018–19, NSW recreational fishery retained harvest estimates for all sea urchins was about 1 t (~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 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 fringe and barrens habitat and calculations of the area of these habitats (out to 100 m from shore) were completed in NSW in 2000. From this study the biomass of Longspined Sea Urchins in fringe habitat was estimated to be about 20 000 t. This biomass estimate was considered close to unexploited levels because of limited fishing prior to 2000, and together with deterministic estimates of Maximum Sustainable Yield (MSY), that suggested annual catches of 1–5 per cent of the unexploited biomass, catches of 200–1000 t were considered to be 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 Urchins 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 per cent of sites investigated had either no change or fluctuations (±10%) in area of barrens. In the remaining 45 per cent of study locations, barrens area had increased on average ~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 Urchins from NSW coastal reefs in 2000, together with consistent, relatively low annual levels of commercial harvest (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.

New South Wales – Indigenous 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 fishing licence under the provisions of the Commonwealth’s Native Title Act 1993.

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. 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.
3. 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.
4. Conron, SD, Bell, JD, Ingram, BA and Gorfine, HK 2020, Review of key Victorian fish stocks — 2019, Victorian Fisheries Authority Science Report Series No. 15, First Edition, November 2020. VFA: Queenscliff. 176pp.
5. Cresswell, K, Hartmann, K., Gardner, C., Keane, J. Tasmanian Longspined sea urchin fishery assessment 2018/19
6. Cresswell, K. A., J. P. Keane, E. Ogier, and S. Yamazaki. 2019. Centrostephanus subsidy program: initial evaluation. Institute for Marine and Antarctic Studies, University of Tasmania, Hobart, Tasmania.
7. Edgar, G. J., and N. S. Barrett. 1997. Short term monitoring of biotic change in Tasmanian marine reserves. Journal of Experimental Marine Biology and Ecology 213:261-279
8. 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
9. Henry, GW and Lyle JM, 2003, The National Recreational and Indigenous Fishing Survey. Tasmanian Aquaculture and Fisheries Institute, Hobart. FRDC 99/158.
10. Johnson, C. R., S. C. Banks, N. S. Barrett, F. Cazassus, P. K. Dunstan, G. J. Edgar, S. D. Frusher, C. Gardner, M. Haddon, F. Helidoniotis, K. L. Hill, N. J. Holbrook, G. W. Hosie, P. R. Last, S. D. Ling, J. Melbourne-Thomas, K. Miller, G. T. Pecl, A. J. Richardson, K. R. Ridgway, S. R. Rintoul, D. A. Ritz, D. J. Ross, J. C. Sanderson, S. A. Shepherd, A. Slotvvinski, K. M. Swadling, and N. Taw. 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.
11. Johnson, C. R., S. D. Ling, J. Ross, S. Shepherd, and K. Miller. 2005. Establishment of the longspined sea urchin (Centrostephanus rodgersii) in Tasmania: first assessment of potential threats to fisheries. Fisheries Research and Development Corporation
12. Ling, S. D. 2008. Range expansion of a habitat-modifying species leads to loss of taxonomic diversity: a new and impoverished reef state. Oecologia 156:883-894.
13. Ling, S. D., and J. P. Keane. 2018. Resurvey of Longspined sea urchin (Centrostephanus rodgersii) and associated barren reef in Tasmania. Hobart.
14. Ling, S. D., C. R. Johnson, S. D. Frusher, and K. R. Ridgway. 2009a. 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.
15. Marzloff, M. P., L. R. Little, and C. R. Johnson. 2016. Building Resilience Against Climate Driven Shifts in a Temperate Reef System: Staying Away from Context-Dependent Ecological Thresholds. Ecosystems 19:1-15.
16. Murphy, J.J., Ochwada-Doyle, F.A., West, L.D., Stark, K.E. and Hughes, J.M., 2020. The NSW Recreational Fisheries Monitoring Program - survey of recreational fishing, 2017/18. NSW DPI - Fisheries Final Report Series No. 158.
17. Ridgway, K. R. 2007. Long-term trend and decadal variability of the southward penetration of the East Australian Current. Geophysical Research Letters 34
18. 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.
19. 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.
20. 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.