Abundance, size and biomass of long-spined sea urchins (Centrostephanus rodgersii) and red sea urchins (Heliocidaris tuberculata) in New South Wales, Australia

C. Blount; D. G. Worthington; M. Byrne; R. C. Chick; K. Organ; N. Knott; N. L. Andrew

doi:10.1071/MF23212

RESEARCH ARTICLE (Open Access)

Previous Contents Vol 75(16)

Abundance, size and biomass of long-spined sea urchins (Centrostephanus rodgersii) and red sea urchins (Heliocidaris tuberculata) in New South Wales, Australia

C. Blount

^A ^B ^C ^* , D. G. Worthington ^D , M. Byrne ^C ^E , R. C. Chick

^F , K. Organ ^A , N. Knott

^F and N. L. Andrew ^B

+ Author Affiliations

- Author Affiliations

^A NSW Department of Primary Industries and Regional Development, 66 Harrington Street, Sydney, NSW 2000, Australia.

^B Australian National Centre for Ocean Resources and Security, University of Wollongong, Wollongong, NSW 2500, Australia.

^C Marine Studies Institute, University of Sydney, Sydney, NSW 2006, Australia.

^D Ambrad Consulting, Wildes Meadow, NSW 2577, Australia.

^E School of Life and Environmental Sciences and Marine Studies Institute, University of Sydney, Sydney, NSW 2006, Australia.

^F NSW Department of Primary Industries and Regional Development, Taylors Beach, NSW 2316, Australia.

^* Correspondence to: craig.blount@dpi.nsw.gov.au

Handling Editor: Melanie Bishop

Marine and Freshwater Research 75, MF23212 https://doi.org/10.1071/MF23212

Submitted: 28 October 2023 Accepted: 24 September 2024 Published: 28 October 2024

© 2024 The Author(s) (or their employer(s)). Published by CSIRO Publishing. This is an open access article distributed under the Creative Commons Attribution-NonCommercial-NoDerivatives 4.0 International License (CC BY-NC-ND)

Abstract

Context

Detailed demographic information for the commercially harvested long-spined sea urchins (Centrostephanus rodgersii) and red sea urchins (Heliocidaris tuberculata) on nearshore reefs of New South Wales is unavailable.

Aims

This is the first detailed study of abundances and sizes of these sea urchin species on shallow reefs of New South Wales where the fishery operates.

Methods

Divers counted sea urchins and measured their sizes in transects in the nearshore mosaic habitat and in extensive barrens habitat at 51 sites along ~800 km of coast.

Key results

Centrostephanus was found at most sites in both habitats, whereas Heliocidaris was found at lower densities and at fewer sites. Heliocidaris was rare in the far south and in barrens habitat. Centrostephanus was, on average, smaller in barrens habitat than in the nearshore mosaic habitat, and size structures shifted towards smaller individuals from north to south.

Conclusions

Centrostephanus occurred at higher densities than did Heliocidaris and had a broader distribution along the coast and across the nearshore reefs where the fishery operates.

Implications

This study provides a historical baseline for these commercially and ecologically important species. The small biomass of Heliocidaris (~3% that of Centrostephanus) and its restricted distribution suggest it is vulnerable to overfishing.

Keywords: abundance, barrens, biomass, Centrostephanus rodgersii, density, distribution, Heliocidaris tuberculata, macroalgae, size structure.

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