Standard Talk (15 mins) Australian Society for Fish Biology Conference 2022

Assessing sustainability of data deficient bycatch species in a north Australian trawl fishery - CANCELLED (#13)

Grant Johnson 1 , Rik Buckworth 2 3 , Clive McMahon 4 5 , Jonathon Smart 6 , Charlie Huveneers 7
  1. Department of Primary Industry and Fisheries, Northern Territory Government, Darwin, Northern Territory, Australia
  2. Sea Sense Australia Pty Ltd, Tasmania
  3. CSIRO Oceans and Atmosphere and Charles Darwin University, Darwin, Northern Territory
  4. IMOS Animal Satellite Tagging, Sydney
  5. Sydney Institute of Marine Science, Mosman, NSW
  6. SARDI Aquatic Sciences, Adelaide, South Australia
  7. College of Science and Engineering, Flinders University, Adelaide, South Australia

Trawl fisheries are often criticised for their indiscriminate nature, catching a broad range of target, bycatch, and byproduct species. In these fisheries, research and management are often directed towards ensuring sustainability of the most economically-important species, with evaluation of the sustainability of byproduct species often considered a lower priority. The Northern Territory Demersal Fishery, the Northern Territory’s largest in terms of catch and value, is no exception.

The target species in this fishery, Saddletail (Lutjanus malabaricus) and Crimson Snapper (L. erythropterus) have robust stock assessments, but there remain fundamental gaps in our knowledge of catch rates, biology, and stock connectivity for the over 200 bycatch species. These knowledge gaps preclude the use of traditional stock assessments, but the risk this growing fishery poses to the bycatch species it interacts with needs to be assessed to meet the fisheries’ obligations to implement ecosystem-based fisheries management.

Contemporary risk assessment approaches such as Sustainability Assessment for Fishing Effects (SAFE) offer a way forward. This data poor risk assessment technique allows the fishing impact of a large number of bycatch species to be relatively quickly assessed. In this project, we used the Northern Territory Demersal Fishery as an example of how SAFE can be used to assess the sustainability of the large number of diverse bycatch species this fishery interacts with. Results suggest that risk to bycatch species in this fishery is currently low, although some elasmobranch species maybe approaching medium risk thresholds and as the fishery grows the impact on these species will need to be carefully monitored. To mitigate this impact we suggest that these species should be prioritised for future research, enabling higher levels of stock assessment, so that there is greater certainty that catches of these species remain sustainable into the future.