Population dynamics of Turbo militaris (Gastropoda: Turbinidae) on rocky shores in a subtropical marine park: implications for management

Abstract

Understanding the relative impacts of harvesting across an area such as a marine park is vital if the goals of fisheries management are to be met. Given their accessibility, densities of targeted intertidal turbinids should be relatively simple to quantify; however, natural spatial and temporal variability in these populations has hampered this effort. This study aimed to quantify short-term population dynamics of Turbo militaris in relation to current zoning regulations and accessibility. While our results reflected the variability found by other studies, we also detected significantly lower densities at a headland where harvesting is known to occur, and found a trend towards denser aggregations at more remote locations. Importantly, we found that densities at some locations were so low that current fisheries bag limits may be ineffective for protecting populations at local scales. Comparisons between study sites suggest a combination of no-take zoning and inaccessibility may provide the most effective protection for this species. However, a greater understanding of the wider impacts of harvesting, and processes affecting recovery, are essential to ensure sustainable management of this fishery.

Keywords:

• accessibility
• harvesting
• size
• spatial variation
• temporal variation

Acknowledgements

Thanks to Alexia Graba-Landry, John Shatrov and Crystal Harris who donated so much of their time and energy to the collection of data, under often less than ideal circumstances. The NSW Marine Parks Authority funded the fieldwork component of this project, which was part of the Honours research by the first author. The staff and affiliates at the NMSC provided invaluable assistance and support. SCUs Marine Ecology Research Centre provided additional support for the project. We also thank the anonymous reviewers who provided comments which helped improve the manuscript.

Disclosure statement

No potential conflict of interest was reported by the authors.

Supplementary data

Figure S1. Size and frequency histograms for populations of Turbo militaris over the three sampling periods: Flat Top Point, Woolgoolga, Mullaway and Arrawarra.

Figure S2. Size and frequency histograms for populations of Turbo militaris over the three sampling periods: Corindi Rock Platform, Station Creek, Jones Point and Diggers Camp.