Can commercial harvest of long-spined sea urchins reduce the impact of urchin grazing on abalone and lobster fisheries?
University of Tasmania (UTAS)
The long-spined sea urchin Centrostrephanus rodgersii has gradually increased in extent and biomass on the East coast of Tasmania over the past three decades. Options for direct and indirect intervention are being considered to limit numbers of this urchin to that required to minimise the destruction of the kelp and understory habitat essential for other benthic species such as abalone and rock lobster. Over the past two years a fledgling urchin harvest industry has developed in Tasmania, with the potential for market demands to create a significant fishery in terms of harvest biomass. Whether harvesting of urchins is beneficial (synergistic) to existing fisheries needs to be determined to inform development of a Harvest Strategy of all species reliant on healthy shallow (<20m) sub-tidal ecosystems. The efficacy of commercial urchin harvesting as a ‘control tool’ is dependent on the degree of spatial overlap with other fisheries (co-dependent on habitat), the capacity of urchin harvesting to minimise localised destructive grazing, and, whether the urchin harvest is economically sustainable given the practical limitations of harvesting at depth.
1. Determine spatial location and extent of overlap between Centrostephanus and existing fisheries
2. Application of coastal exposure indices for identifying potential urchin harvest locations
3. Determine dive profile strategies to enable safe harvest of urchins at depths greater than 15m