Standard Presentation 2024 Australian Marine Sciences Association Annual Meeting combined with NZMSS

Signals from the deep: Analysing trends in species composition and catch of data-poor deepwater shark species   (#521)

Sushmita Mukherji 1 , Colin Simpfendorfer 1 , Nils Krueck 1 , Natalie Dowling 2
  1. Institute for Marine and Antarctic Studies, University of Tasmania, Hobart, Tasmania, Australia
  2. Commonwealth Scientific and Industrial Research Organisation , (CSIRO), Hobart, Tasmania, Australia

Sixteen deepwater shark species caught in southeastern Australia are managed as a “basket” species group within the Australian Southern and Eastern Scalefish and Shark Fishery (SESSF). Deepwater sharks are highly vulnerable to exploitation with many populations rapidly depleted and slow to recover from intensive fishing. Adequately describing and interpreting spatial and temporal trends in catch and fishing effort is vital for accurately assessing the dynamics of exploited populations, yet this is very difficult to achieve in a meaningful way for a basket of species with various data quality issues. Here we analyse trends in species composition and catch of deepwater sharks from SESSF logbook and observer data and attempt to predict catch of species groups within the basket using a generalised linear mixed effects model. The extent to which meaningful insights can be obtained is critical to understand when considering the available data to inform an empirical or model-based stock assessment, and the means by which the successful management of deepwater shark basket species may be achieved within the Australian Fisheries Management Authority harvest strategy framework.