Synthesis of existing data on the early life history of southern Australian finfish
CSIRO Oceans and Atmosphere Hobart
Managers need to know the level of regional connectivity of fisheries resources in order to manage them both equitably and sustainably. Managers need to know where the source populations are for the fisheries that they manage, over what area they recruit and what the levels of variability in recruitment are likely to be. There are two critical areas as well as a number of basic biological issues that this proposal addresses. (i) Stock structure: Stock assessment and management cannot sensibly proceed without knowledge of what the structure of the stock is. Yet for 12 of the 17 species listed in the SEF strategic plan and 30 of the 38 species of southern Australian finfish listed in the 1993 BRS/FRDC funded Fisheries Resources Atlas, information on stock structure is identified as either lacking or inadequate. Some of the major determinants of stock structure are where fish spawn, how many spawning areas there are, how far and to what extent are eggs and larvae transported and mixed between regions and over what areas do fish recruit. We continue to use proxies for this information (eg genetics, morphormetrics, microchemistry) because it has previously been both difficult and expensive to look at such early life history processes directly. (ii) Environmental variability: The biological systems with which resource managers work and the physical environment to which these systems are integrally linked are inherently variable. Physical circulation and its variability is undoubtedly a driving force for recruitment processes and the extent to which resources are connected between regions. We are continually reminded that recruitment for many fish in southern Australia is highly variable, shows links to environmental forcing and that these factors are poorly accounted for in the way we currently assess and manage our fisheries resources. (iii) Critical basic biological parameters for wild fisheries and aquaculture: For many wild fisheries resources we still do not know where and when fish spawn, where are critical nursery areas, what are the pathways from spawning to nursery areas, what fish are suitable for fisheries independent biomass assessment via egg/larval surveys or acoustic assessment of spawning aggregations. The aquaculture sector needs to know how long the larval stage of prospective species is, how fast larvae grow, what they eat and what are their preferred temperature and salinity requirements to successfully plan and establish operations. There is no one data set or project that will solve these issues but there is a common theme to all - early life history (ELH). It is no longer too hard to look at this area. Current studies under way at CSIRO lead by B. Bruce (ELH, recruitment dynamics and connectivity of southern rock lobster resources FRDC 96/107) and MAFRI lead by F. Neira (regional connectivity of King George whiting via larval transport FRDC 96/116) are already providing much of this information for those species. The samples necessary for this project have already been collected - approximately 10,000 over the last 10 years representing some $7.5 MILLION in research and commercial vessel time. This is a sample set of National significance. Many hundreds of man-hours have already been spent sorting many of these samples. Two FRDC funded projects have been completed that (a) provide the tools necessary to identify larvae (FRDC 94/129) and (b) ensure the availability and safety of previously collected samples (FRDC 94/55). Considerable resources have been spent on gathering and sorting samples additional to those that were archived as part of FRDC 94/55 in further preparation for this project. Several years have been spent developing the skills required to marry the these biological data sets with ocean environment information. The value and benefit of these initiatives will only be achieved when the data stored in these samples are collated, analysed and made accessible. These are the primary goals of this project. The results of this project will be of use to fisheries scientists, oceanographers, fisheries and coastal managers, water authorities, the EPA, aquaculture and the private sector (eg oil/gas companies) and will represent a significant advance in our understanding of the early life history of southern Australian fish and the dynamics of southern Australian fisheries resources. This project derives its origin directly from high priority research needs identified under the SEF strategic plan, discussions with State fisheries institutions, recommended further research identified by several other FRDC projects and the development of the prerequisite skill and sample base over the last 10-15 years.
1. To compile and analyse available information on the early life history (ELH) of southern Australian fish in order to provide supporting data for the regional management of fisheries resources, assessment of stock structure and assessment of environmental forcing of recruitment processes.
2. To examine the regional connectivity of fin fish resources via the dispersal of ELH stages
3. To produce an atlas of ELH data for southern Australian fin fish including information (by species) on larval distribution, water mass affinities, timing and location of spawning, larval age and growth, and larval dispersal patterns.
Principal Investigator: B.D. Bruce and R.W. Bradford