Dhufish is one of the most commercially and recreationally important finfish in Western Australia. Together with pink snapper it accounts for almost half of the commercial catch of the west coast demersal scalefish. Recently, commercial and recreational fishers reported that they moved further offshore to catch dhufish suggesting heavy fishing in nearshore areas and the threat of overfishing offshore amplified with increasing use of GPSs. Another concern is a drop in the maximum observed age of dhufish by 9 years from 41 to 32 years old and a decrease in the proportion of dhufish > 13 years of age in the catches from 28 to 9% over the last decade. The limited knowledge of this species points to very limited dispersal over its range enhancing concerns about the vulnerability of dhufish to overexploitation. Understanding the physical and biological processes that underpin recruitment success in dhufish is of key importance to making predictions about the future productivity and management of the fishery. Recent research indicated that the recruitment strength will depend on spawning output of adults, oceanographic conditions and food availability during the planktonic stage. Lack of knowledge of location and transport of eggs and larvae fundamentally limits understanding of the recruitment of dhugfish. The project aims at locating the early life stages and their transport areas such that sustainability for this species can be pursued.

* The WA dhufish is a premium quality finfish with attributes suitable for aquaculture. In addition to the attractiveness of the species for aquaculture, Fisheries WA (FWA) have recently identified dhufish as a species "at risk" and requiring close monitoring. The development of reliable culture technology for dhufish and the subsequent establishment of a dhufish culture industry has potential to alleviate commercial fishing pressure.

* Jurien Fishfarmers PTY LTD has considerable investment in marine finfish aquaculture in WA. They currently have black bream and pink snapper in seacage off Jurien and are looking at a range of other higher value species. This company and others have considerable commercial interest in the development of high value species for aquaculture. Dhufish is one these target species.

* Previous work has shown that WA dhufish can be cultured successfully; however, production remains unreliable. It is therefore necessary to extend this work to develop reliable and cost-effective techniques for egg production, larval rearing, weaning and grow-out.

* Two FRDC funded research projects are in progress. One study is addressing health issues in WA dhufish (eg gonad parasite, exophthalmia). The other is examining the development of the eye with a view to optimising culture parameters. The success and application of these projects will be limited if the FMC-based dhufish culture project (this current application) is not continued.

* Domestication is known to greatly improve success of reproduction in captivity. The 94 eighteen-month-old F1 dhufish held at FMC therefore represent a key resource for maximising the benefits from previous FRDC funding and ensuring the success of the project. However, the project needs to be continued in order to grow these fish through to maturity. Research with other species throughout the world and at FMC suggests that the problem of an unreliable supply of good quality eggs from dhufish could be largely overcome when the F1 fish reach maturity (expected in 1999/2000).

This project will greatly assist the Fremantle Maritime Centre to establish the light regimes required for the WA dhufish larvae and will provide greatly needed support for the larval rearing portion of the project. The information provided should enable the FMC to avoid long term trial and error light regime experimentation and increase larval survival. The information obtained will also be of benefit to Murdoch University (FRDC Project 96/103 - Determination of biological parameters required for managing the fishery for Western Austration dhufish) to assist in identifying (currently unknown) areas which may act as nursery grounds for the WA dhufish larvae.