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Limited effectiveness of divers to mitigate ‘barrens’ formation by culling sea urchins while fishing for abalone

Citation

Sanderson, JC and Ling, SD and Dominguez, JG and Johnson, CR, Limited effectiveness of divers to mitigate barrens' formation by culling sea urchins while fishing for abalone, Marine and Freshwater Research, 67, (1) pp. 84-95. ISSN 1323-1650 (2016) [Refereed Article]

Copyright Statement

Journal compilation copyright CSIRO 2016

DOI: doi:10.1071/MF14255

Abstract

Climate-driven incursion of the long-spined sea urchin (Centrostephanus rodgersii) in eastern Tasmania has prompted calls for strong management intervention given the urchins’ capacity to overgraze kelp beds and cause local collapse of valuable reef fisheries. We examined the effectiveness of commercial divers culling C. rodgersii while undertaking otherwise normal fishing for black-lip abalone (Haliotis rubra). Diver effort appears to be driven by fishing yield and not the opportunity to maximise numbers of urchins culled; the greatest culls occurred on shorter dives when abalone fishing was poor. Despite culling thousands of urchins, divers culled urchins only from within a small proportion of the total barrens patches on particular reefs. Thus, urchin density, size-frequency of barrens patches, and benthic community structure showed no detectable change relative to ‘no-cull’ control reefs. Nonetheless, divers were effective in culling urchins in the few patches they targeted, and these patches were quickly recolonised by canopy-forming kelps. Ongoing urchin culling by abalone divers will increase resilience of the kelp habitats on which the valuable abalone fishery depends, but only at highly localised spatial scales (10 m). The effectiveness of this control strategy is dependent on sustainable local harvest of abalone warranting recurrent diver visitation to affected sites. However, abalone divers culling urchins while fishing are unlikely to control urchin densities at scales ≥102 m.

Item Details

Item Type:Refereed Article
Keywords:control, fisheries, kelp beds, overgrazing, phase shift, range-extension
Research Division:Biological Sciences
Research Group:Ecology
Research Field:Marine and Estuarine Ecology (incl. Marine Ichthyology)
Objective Division:Environment
Objective Group:Ecosystem Assessment and Management
Objective Field:Ecosystem Assessment and Management of Marine Environments
Author:Sanderson, JC (Dr Craig Sanderson)
Author:Ling, SD (Dr Scott Ling)
Author:Dominguez, JG (Mr Gabriel Dominguez Sarmiento)
Author:Johnson, CR (Professor Craig Johnson)
ID Code:108108
Year Published:2016
Web of Science® Times Cited:1
Deposited By:Centre for Ecology and Biodiversity
Deposited On:2016-04-06
Last Modified:2016-12-06
Downloads:0

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