Plenary Presentation Australian Society for Fish Biology Conference 2022

Reproductive behaviour of the Murray cod (Maccullochella peelii) in the wild. (#46)

Gavin L Butler 1 , Tom R Davis 1 , Brooks G Steven 2 , Chris Bowen 1 , Leo M Cameron 1 , Stuart J Rowland 1 , John St Vincent Welch 1 , Luke Carpenter-Bundhoo 3 , Daniel Smith 2
  1. Fisheries NSW, Grafton, NSW, Australia
  2. Qld Department of Agriculture, Fisheries and Forestry, Brisbane, Queensland, Australia
  3. Australian Rivers Institute, Griffith University , Nathan, Qld, Australia

Despite Murray cod Maccullochella peelii (Mitchell) being of immense societal and ecological value in south eastern Australia, the reproductive ecology of the species remains largely unknown in a riverine context. From 2015 to 2019 we used a combination of bio-telemetry and underwater imagery to quantify the behaviour of Murray cod across their breeding cycle in each year in the Northern Murray-Darling Basin, Australia. In most years, breeding behaviour (including nest site selection) was observed from early-August, with the population spawning period spanning late-August until the end of October. The onset of breeding behaviour was positively correlated with week-of-year and spawning was related to moon-phase. Most nesting occurred in shallow water on hard substrate underneath undercut banks. Nests were most often located in disconnected pools essentially in the absence of flow, indicating a lack of flow dependence for spawning. Larvae demonstrated active swimming and retention to the nest until a stage of dispersal, which was not dominated by downstream movements. Unintended disturbances to nests in some cases resulted in negative impacts on egg and larval survival. Current regulations warrant refinement to accommodate these recent findings to safeguard the long-term conservation of the species across all its biogeographic range.