Strong relationships between levels of puerulus settlement and recruited stock abundance in the red rock lobster ( Jasus edwardsii) in New Zealand

Abstract

Any demonstrable relationship between levels of settlement and subsequent strength of recruitment to the fishery is of great interest to the managers of rock lobster fisheries. A project to estimate levels of settlement of the puerulus stage of the red rock lobster, Jasus edwardsii, on crevice collectors around the main rock lobster fishing shores of New Zealand has been in place for more than quarter of a century, with considerable temporal variation but also strong temporal and spatial consistencies in settlement. There are significant correlations between settlement level and the fishery catch per unit effort (CPUE) response for most fishery areas, at time lags between settlement and recruitment consistent with what is known of juvenile growth rates. There are also significant correlations when more than one settlement year is correlated against each year of CPUE, to account for variable growth rates between individual lobsters. There was no concurrence between field and fishery model estimates of recruitment for the three fishery areas with sufficient data, revealing a different interpretation of annual rates of recruitment to the fishery between the two approaches. The reasons for the discrepancy are unclear, but one possibility is that the model estimates of recruitment are poor.