Dr John Keane1, Miss Olivia Johnson1, Dr Scott Ling1, Dr Craig Mundy1, Dr Katie Cresswell1
1Institute for Marine and Antarctic Studies, Taroona, Australia
The climate driven range extension of the Longspined Sea Urchin, Centrostephanus rodgersii, in south-eastern Australia has led to the establishment of a population off the island state of Tasmania to increase from zero to almost 20 million within five decades. Extensive overgrazing has resulted in 15% of the eastern coast becoming unproductive urchin barren, with predictions barrens could increase to more than 50%. Physical, biological and commercial control measures have all been proposed and researched in an attempt to stem the booming urchin population. Here we review the array of mechanisms (predation, commercial harvesting, paid and recreational culling, quick-liming, robotics) and conclude that a spatially integrated, temporally adjusted, multi factorial approach is required. Variable barren extent both latitudinally and bathymetrically dictates efficiency of control measures, while increasing depth also excludes some mechanisms (e.g diving). Short term and expensive mitigation (culling, quickliming) needs to transition to sustainable management options (commercial harvest, natural predation). A fine scale spatial assessment of the extent of urchin barrens is required to underpin the spatial application of the varied measures to optimise biological and economical efficiencies. Here Local Ecological knowledge (LEK – diver derived) and underwater video is modelled to obtain fine scale data over 300 km of coastline. From this fine scale data, optimisation of control mechanisms can be achieved.
Dr John Keane is a Research Fellow within the Institute for Marine and Antarctic Studies at the University of Tasmania. He has over a decade of fisheries research experience, predominantly focusing on commercial dive and small pelagic fisheries. The climate driven range extension of the Longspined Sea Urchin has led him to oversee the establishment of a new fishery for this species.