Impact of the Leeuwin Current on the spatial distribution of the puerulus settlement of the western rock lobster (Panulirus cygnus) and implications for the fishery of Western Australia

Previous studies have shown that the strength of the Leeuwin Current is correlated with the level of the puerulus (post-larval stage) settlement in the western rock lobster (Panulirus cygnus). The level of puerulus settlement has also been shown to be a reliable predictor of catch in the rock lobster fishery in Western Australia, 3 and 4 yr later. This study examines the impact of the south-flowing Leeuwin Current on the spatial distribution of the puerulus settlement along the coast based on information from 10 settlement sites. In years of strong Leeuwin Current, the location of the peak settlement occurs further south by up to 2 degrees latitude compared with years of weak Leeuwin Current. The key months of Leeuwin Current strength that affect the abundance of the puerulus settlement are generally February to April, during the early larval stages. However, the months that affect the spatial distribution are from June onwards, which is closer to the period of puerulus settlement that starts in about August each year. The mean latitude of puerulus settlement shows a very good relationship with Leeuwin Current strength in June to December (r = 0.86, P < 0.001). The variation in spatial distribution in puerulus settlement can be used to predict the spatial distribution of fishing effort and catch, 3 and 4 yr later (r = 0.78 and 0.84, respectively, P < 0.001).