There is considerable scope to enhance spatially-based management arrangements for species with broad or disjunct distributions, or species that are targeted by different gears in different areas or habitats. For example, current SESSF management arrangements do not consider stock structure in Blue-eye Trevalla, although it ranges from WA to Queensland and beyond Australian waters, and preliminary analysis showed some evidence for separate stocks between the SESSF and ECDW seamounts. There is an immediate need to develop and incorporate new spatially-based arrangements into management of Blue-eye Trevalla in response to complex spatial patterns in the fishery that include a change of fishing methods through time, whale interactions increasing in some areas, re-location of effort into underutilized locations (e.g. ECDF seamounts), and the series of recent and planned area closures that include Commonwealth Marine Reserves (CMR) in the GAB, off the eastern seaboard and on the offshore Tasmantid Seamount Chain, and fishery closures being implemented by AFMA and NSW Fisheries to project Harrisson’s and Southern Dogfish. There is a more general need to assess options for managing separate stocks of other species – such as regionalising TAC’s – and to evaluate options against EBFM performance measures that include economic and environmental indicators.
Project number: 2013-015
Budget expenditure: $241,276.00
Principal Investigator: Alan Williams
Organisation: CSIRO Oceans and Atmosphere Hobart
Project start/end date: 30 Jun 2013 - 2 Oct 2015
1. Define Blue-eye Trevalla subpopulation structure, especially between the SESSF, ECDF and outside Australia’s EZ, using otolith elemental and stable isotopic chemistry.
2. Evaluate the potential of other biological data (age, size frequency and maturation stage) to substantiate or refute potential subpopulation spatial patterns.
3. Infer patterns of dispersal and recruitment using otolith chemistry in conjunction with ocean circulation models.
4. Develop methods to develop management options that capture the spatially and temporally complex Blue-eye Trevalla fishery and which account for extensive recent fishery and marine reserve closures.
5. Use Blue-eye Trevalla as a model to develop and evaluate options for other species.
Author: Alan Williams