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.
History
Publication title
Marine and Freshwater Research
Volume
67
Pagination
84-95
ISSN
1323-1650
Department/School
Institute for Marine and Antarctic Studies
Publisher
CSIRO Publishing
Place of publication
150 Oxford St, Po Box 1139, Collingwood, Australia, Victoria, 3066
Rights statement
Journal compilation copyright CSIRO 2016
Repository Status
Restricted
Socio-economic Objectives
Assessment and management of terrestrial ecosystems