The long lining in Port Phillip Bay is a traditional fishery dating back to the European settlement in Victoria. However, the future of the net and line fisheries are under review following annoucements by the Premier in 1996. The recreational peak body (VRFish) have serious concerns expressed in their vision statement which stated " a detailed study of the effect of netting and longlining in the bays and inlets should be conducted as a matter of urgency".
These concerns relate to the perception that commercial fishing has caused a decline in the recreational snapper catches in Port Phillip Bay. There is an urgent need to investigate this issue which is clouded with uncertainty and a lack of scientific data. For example, Port Phillip Bay is known as a spawning area for snapper and the movement of mature fish is an important feature of the commercial and recreational fisheries. However, the proportion and variability of the stock spawning in Port Phillip Bay each year is unknown. It is therefore unclear whether the perceived decline in snapper catches is due to high levels of fishing or due to environmentally induced changes in distribution or migration.
The relative distribution of the stocks and movement patterns of different age groups in Victoria is poorly understood, and there is a need for more information on the basic biology of snapper to support stock assessments and management plans. While stock assessments for the western stock have only recently been attempted, there is insufficient data to improve predictive models, especially for the eastern stock. While catches are low, routine monitoring is insufficient to obtain the samples required. This project is intended to provide a three year focus on snapper research to collect the neccessary information to address fundamental management issues such as appropriate size limits and seasonal or area closures, and to determine the movement of snapper between Port Phillip Bay, coastal waters and other states. Essential data on the size at maturity, reproductive biology, age structure and growth of eastern and western snapper stocks are needed to determine the life history parameters. There is also an urgent requirement to develop snapper stock assessment models in order to provide better advice on stock status for fishery management plans.
Historic tagging studies since 1948 released 8,132 snapper to determine movements and growth. The tagging data collected needs to be re-analysed with recently developed techniques and used as a basis for planning new tagging experiments as part of the ANSA VICTAG program. The VICTAG program encourages the participation of anglers in fisheries research , but currently there is no formal research plan for VICTAG or involvement by the commercial sector.
The first indication of the spawning location came from an extensive ichthyoplankton survey of Port Phillip Bay in 1995/96. However, a more intensive survey is needed to identify the area and spawning season and to correlate this information with environmental conditions and to assess the water quality and habitat requirements for reproduction of snapper. Variability in recruitment has been detected from annual research trawls in Port Phillip Bay, which may in turn be related to favourable environmental conditions such as water temperature as in New Zealand. A detailed examination of the ultra structure of sectioned otoliths is required to determine whether a similar relationship can be extended to snapper recruitment in Victoria .
