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Understanding the effects of egg loss from fisher handling to improve conservation of a threatened freshwater crayfish, Euastacus armatus

Scott Raymond , Charles Todd , Jordi Ryall

Abstract

Context. Handling of wild animals can have adverse effects on individuals that scale up to impact populations and ultimately species. Limited mobility and high harvest pressure exposes the threatened Australian freshwater crayfish Euastacus armatus to multiple handling events by fishers that cause egg loss. Aim. Our aim was to assess the effects from harvest pressure on the reproductive output of an E. armatus population. Methods. A stochastic model based on empirical data and estimated harvest pressures was used to predict the effect of repetitive handling of individuals on a population of E. armatus subject to harvest and consequent egg loss. Key results. Egg loss resulted in substantial predicted population-level declines, most pronounced in populations subject to high and extreme harvest pressures. Conclusions. We advocate educating fishers to visually determine the reproductive condition of female crayfish by inspecting gonopore setation, eliminating the need for unfurling the tail. Implications. Maximising species reproductive output through limiting handling loss supports the management and conservation of E. armatus populations.

MF23180  Accepted 26 March 2024

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