The effect of environment on puerulus settlement of the western rock lobster (PanuUrus cygnus) in Western Australia

Abstract

ABSTRACTThe level of puerulus settlement has proven to be a reliable predictor of the recruitment to the western rock lobster (Panulirus cygnus) fishery three and four years later. It is generally accepted that the early larval stages are moved offshore by wind‐driven surface currents. Previous studies have shown that coastal sea level, used as an indicator of the strength of the Leeuwin Current flowing down the west coast of Australia, was positively related to the level of puerulus settling on the inshore reefs after a 9‐ to 11‐month larval life. In this paper a significant relationship is also demonstrated between winter/spring storms, which are usually associated with onshore westerly winds, and the level of puerulus settlement (multiple correlation of 0.83, R1= 0.68, n = 22). Rainfall from coastal localities was used as an index of the storms. The residuals from this relationship showed a significant positive autocorrelation. The autocorrelation was incorporated into the relationship by using time series analysis with a transfer function model and a first‐order autocorrelation (R2= 0.76).The possible relationship between storms and the Leeuwin Current and their effect on the puerulus settlement are considered, and the potential for the environmental variables to bias or obscure the spawning stock recruitment relationship is discussed.