Delineating fish-habitat associations for spatially based management: an example from the south-eastern Australian continental shelf

A multi-scale, multi-gear survey identified the spatial structure and compo sitions of fish communities from a range of seabed types on the south-easte rn Australian continental shelf (25 m to similar to 200 m depth). Most comm unities are species-rich and contain many shared species. Multivariate anal ysis of distributions of 201 fishes showed communities to be correlated wit h depth, latitude and seabed type; correlation with hydrodynamic climate is suggested by patterns in morphology. Depth-related patterns occurred on so ft-sediment and hard substrata; strong latitudinal (south-west/north-east) patterns identify the area as a faunal transition zone with a major faunal disjunction extending across the shelf. Community patterns were overlaid on distributions of substrata to produce a biophysical map. This mapping proc ess is discussed in the context of spatial management: the ecologically sig nificant scale at which to map habitat features and definition of managemen t units for ecosystem-based management. A hierarchy of scaled ecological un its is being developed for Australia's National Representative System of Ma rine Protected Areas (NRSMPA); given the scope of the NRSMPA initiative, su rrogate measures of community structure will be required. Maps of substrata and topography, interpreted in the context of the broader depth and latitu dinal community structure and as modified by hydrography, may provide one u seful surrogate.