Oral Presentation Australian Society for Fish Biology Conference 2024

Development of harvest control rules to use with Close-Kin Mark-Recapture based stock assessments (111123)

Pia Bessell-Browne 1 , Laura Tremblay-Boyer 1 , Robin Thomson 1 , Andre Punt 1 , Mark Bravington 2
  1. CSIRO, Hobart
  2. Estimark Research, Hobart

Harvest strategies are a key component of best practice fisheries management. An important element of harvest strategies is the specification of harvest control rules (HCRs), which determine pre-agreed action for fisheries management based on information about the status of an exploited population. HCRs can be applied to not only a range of assessment types with differing data needs but may also be empirical. With accelerating impacts of climate change on fish populations, HCRs that are robust to these changes are required. Close-Kin Mark-Recapture (CKMR) methods are becoming increasingly used to asses fish populations. The technique expands on conventional mark-recapture methods by identifying closely related kin pairs using DNA markers. Assessments based on CKMR data can accurately estimate current absolute abundance and mortality, but provide less information on historical B0, in some cases preventing estimation of current stock status (or depletion). Many conventional HCRs use stock status as a key input, while their performance is also adversely impacted by environmental changes in productivity. Therefore, HCRs that align with the outputs generated by CKMR analyses and that are robust to changing environmental conditions are required. Here we investigate HCRs that are suitable for use with CKMR-based assessment inputs and are also robust to changing environmental conditions and test their performance on a generic teleost and School Shark (Galeorhinus galeus) like species.