Title:

Rebuilding Ecosystem Resilience: assessment of management options to minimise formation of ‘barrens’ habitat by the long-spined sea urchin (Centrostephanus rodgersii) in Tasmania

Project Number:

2007-045

Organisation:

University of Tasmania (UTAS)

Principal Investigator:

Craig Johnson

Project Status:

Completed

FRDC Expenditure:

$828,551.00

Program(s):

Environment

Final Report - 2007-045-DLD - Rebuilding Ecosystem Resilience: Assessment of management options to minimise formation of ‘barrens’ habitat by the longspined sea urchin (Centrostephanus rodgersii) in Tasmania

Final Report
ISBN:978‐1‐86295‐712‐1
ISSN:
Author(s):
Date Published:August 2014
Principal Investigator: Craig Johnson

KeywordsSea urchin, Centrostephanus rodgersii, rock lobster, Jasus edwardsii, abalone, Haliotis rubra, sea urchin barrens habitat, ecosystem based management, modelling, stock rebuilding, maximum economic yield.

Summary:
Outcomes
1. The original proposal posited that if cost effective options could be identified to minimise the impact of C. rodgersii, either in preventing further barrens formation or in rehabilitating existing areas of C. rodgersii barrens, then the State management agency would attempt to develop and implement these options. 
Largely (but not wholly) as a result of the findings of this study, the Minister for Primary Industries and Water announced in August 2013 support for a 10 year strategy to rebuild rock lobster stocks in eastern Tasmania by introducing spatial management of the rock lobster fishery in eastern Tasmania, and limiting the total allowable catch of the commercial sector in eastern Tasmania. Recovery of lobster biomass is likely to both improve the economic efficiency of the fishery as well as reduce the likelihood of significant ongoing C. rodgersii barrens formation.

2. Loss of productive reef from overgrazing by C. rodgersii has direct implications for Tasmanian fisheries, including the two most valuable, abalone and rock lobster. DPIPWE recognises that implementation of effective measures to control C. rodgersii populations strategically (on a large scale) and tactically (on a small scale) will have direct benefits in ensuring the integrity and biodiversity value of rocky reef systems on the east cost of Tasmania and the sustainability of the abalone, rock lobster and scale‐fish fisheries that they support. As a result of this study, it is acknowledged by managers and other stakeholders that a multifaceted approach to managing the threat of establishment of C. rodgersii in Tasmania is warranted, including rebuilding biomass of legal‐sized rock lobsters, facilitating the C. rodgersii harvesting industry,
permitting and encouraging abalone divers to cull urchins while fishing (particularly in high‐yield areas), and examining other means to reduce C. rodgersii densities.

Objectives

1. To assess the effectiveness of translocating large rock lobsters (=135 mm CL) en masse as means of preventing formation of incipient barrens and rehabilitating incipient and extensive barrens.

2. To assess the effectiveness of a range of management options (e.g. imposing upper size limits and spatial management) in building the biomass of large (=135 mm CL) rock lobsters to levels sufficient to limit C. rodgersii populations.

3. To assess the effectiveness of killing or removing sea urchins by abalone divers during the conduct of their fishing activity, as a means of preventing formation of incipient barrens and rehabilitating incipient and extensive barrens.