Estimation the effects of removing Panulirus cygnus pueruli on the fishery stock
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A proposal to support a western rock lobster aquaculture venture with wild-caught pueruli instigated this study of the possible impacts of pueruli removal on the wild Panulirus cygnus fishery in Western Australia. Existing data on puerulus settlement, post-puerulus densities and mortalities, the area of suitable settlement habitat and recruitment rates to the fishery were used to model the impact on the catches of an area between 29S and 30S. Density-dependent mortality between the time that pueruli settle on inshore reefs and the time they move offshore as juveniles to recruit to the fishery is indicated by the model as being high: 80 98% during the first year after settlement (from ages 1 2 years), depending on density-dependent assumptions made about the mortality between puerulus and recruitment to the fishery. As few as 3% of the settling pueruli survive to recruit into the fishery at about 4.5 years of age. The impact of puerulus removals on the subsequent catch was estimated to be slight, unless many millions of pueruli were removed. For example, the removal of 20 million pueruli in a year in which the puerulus settlement size was 600 million would result in a reduction in catch of 0.62%. If desired, such losses could be countered by an effort reduction in the study area of 1%.
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Phillips, Bruce; Melville-Smith, R.; Thomson, A.; Rossbach, M. (2007)Previous studies have shown that western rock lobster pueruli and post-pueruli shelter in small holes and crevices and that suitable shelter in the inshore environment is limited. It is considered that by providing ...
Phillips, Bruce; Melville-Smith, R. (2005)The Western Rock (spiny) Lobster Fishery has 594 boats operating about 57,000 pots. The average annual catch of 11,000 tonnes is valued at around US$150 million. In addition to the commercial catch, recreational fishers ...
Using fine-scale catch predictions to examine spatial variation in growth and catchability of Panulirus cygnus along the west coast of AustraliaDe Lestang, S.; Caputi, N.; Smith, Roy (2009)Puerulus settlement has been monitored throughout the western rock lobster Panulirus cygnus fishery for nearly 40 years. These data, in combination with indices of effort and water temperature, were used to produce ...