Alan Williams, Rudy Kloser, Nic Bax, Bruce Barker, Alan Butler CSIRO Marine Research, Hobart

1. Interactions of fishing gears with seabed habitats on the deep continental shelf and slope off SE Australia Alan Williams, Rudy Kloser, Nic Bax, Bruce Barker, Alan Butler CSIRO Marine Research, Hobart Based on projects funded by CSIRO Marine Research (CMR) Australia’s National Oceans Office (NOO) Fisheries and Research Development Corporation (FRDC)

2. High Decreasing vulnerability Resistance Substrata consolidated by slow -growing structural biota Substrata consolidated by fast -growing structural biota Unconsolidated substrata in high energy environment Unconsolidated substrata in low energy environment Hard banks & unweathered reefs Soft banks & weathered reefs Low Long time to recovery Resilience Short time to recovery Vulnerability: a framework for fishing gear-habitat interactions • Previous work (Bax & Williams, 2001; Fig 8) provides a starting point • Develop it by • borrowing a semi-quantitative methodology from ERA process • considering the likelihood of fishing by gear type

3. Level 2 has a detailed procedure for • Identifying attributes • Assigning ranks (values) • Correlation structure • Missing values • Multiple values etc Increasing Risk High Susceptibility Low Productivity An existing framework: ecological risk assessment for the effects of fishing (ERA) • Assess for each Australian fishery/ major sector • Target species • Bycatch/ byproduct • TEP species • Habitats • Ecological communities Ref: Tony Smith and Alastair Hobday

4. Axis 1: resistance attributes Resistance = "resistance to modification“ (lower resistance = higher vulnerability) Units of study are habitat types Generic for fishing gears At this level: Others Patch size; Currents; Weathering/ geochemistry; Vertical relief; Depth zone; Clast mobility… and from the literature … and the audience

5. Rank 1 2 3 Increasing resistance Resistance example: hardness • Attribute:Hardness • Aspect:Composition of substrata • Rationale: Harder substratum is intrinsically more resistant • Ranks (low = more vulnerable): • Sediments (soft) • Sedimentary lithotypes • Igneous or indurated lithotypes (hard)

6. Axis 2: resilience attributes Resilience = "time taken for return to original ecosystem function, or conservatively, original condition“ (Lower resilience=higher vulnerability) Others?? Connectivity … and from the literature … and the audience

7. Rank 1 2 3 Increasing resilience Resilience example: regeneration time (substrata) • Attribute:Regeneration time (substrata) • Aspect:Accumulation/ replacement times of substrata is variable • Rationale:Substrata have different intrinsic accumulation rates, eg sedimentation, biogenic activity, or structures laid down in geological time • Ranks (low = more vulnerable): • Consolidated substrata • Biogenic • Sediments

8. Shelf and slope South East Fishery data set Data from sampling targeted at contrasting SEF terrains (fisher’s info and acoustics) Habitats (biological facies) based on video score combinations of * Substratum (7 classes) * Geomorphology (10 classes * Fauna (10 classes) Habitats identified to sub-biome (inner/ outer shelf, break, upper/ mid slope), not site Total types = 101

9. Decreasing vulnerability Resistance Igneous rock with large epifauna (3 facies) Sedimentary rock with large epifauna (11 facies) Boulders supporting crinoids; coarse sediments supporting octocorals (5 facies) Resilience Sediments, variously current/ wave rippled/ bioturbated supporting large epifauna (sponges, octocorals, crinoids) (19 facies) Inner shelf sediments supporting small/ encrusting epifauna (5 facies) Sediments, various morphology/ supporting small/ encrusting/ mobile epifauna (58 facies) Semi-quantitative plot

10. The third axis : predicted use • Need to know where the habitat types are (mapped at management scales) • Likelihood of being fished by particular gears • Impacts of particular gears • Predicted value, use and impact • Management options • reduce probability (area management) • reduce impact • (gear modification) X = X

11. 5 - Warehou Flathead 4 3 6 1 7 2 Morwong Ling Mapping habitat distributions at fishery scales Fishing grounds are a good surrogate for habitat distributions at scales relevant to management and fishery use Broad habitat types documented for ~ 500 SEF grounds with fishing industry help (7 here) Effort & catch per species, and $ values (1 km cell resolution) e.g. total trawl effort

12. reef edge Gabo-Howe Reef complex reef boundary from trawl map 1 km Fishery seascape: value and use (Gabo Reef) Reef platform Sediment plain Gillnet Trawl

13. Fishery seascape: vulnerable habitats at margins of Horseshoe Canyon Mobile and removable mudstone boulders (“slabs”) support large epifauna (crinoids and sponges) and high concentrations of commercial fishes overturned 4m wide slab Pink ling

14. Conclusions • Habitat vulnerability can be usefully developed in the ERA framework • Probability of use and impact by particular gears is important • Framework provides a way to direct management and future survey to vulnerable habitats – eg canyons • Interaction with fishers is important for understanding habitat distributions, use and suitable options for sustainable use