Non Technical Summary

Commercial landings of dusky flathead from 4 NSW estuaries were sampled for sex, length and age composition between 1995 and 1997. The data show that the commercial fishery for dusky flathead is primarily sustained by female fish aged between 2 and 4 years and the stock appears to be subject to a high total mortality, suggesting that the stock is over-exploited. Given that a large proportion of the female catch is below the presumed length at first maturity, it is recommended that: (1) the size and age of dusky flathead at first reproduction be determined; and (2) an assessment of altering the current minimum legal length restriction of 36 cm to the proposed 40 cm be made. Because of the weak relationship between length and age of dusky flathead above the minimum legal length, future sampling of catches for stock assessment purposes needs to be age-based and not based on lengths. Other cost-effective alternatives to estimate the age of dusky flathead need to be investigated such as using otolith weights and widths. Further research on dusky flathead is required to assist with stock assessments and the management of the species. Current gaps in knowledge include the rates of growth and exploitation, the species reproductive biology and stock-recruitment dynamics.