Platypus fyke-netting methods: a review of recommended field protocols and options for assessing population abundance

Melody Serena; Geoff A. Williams; Chris Bloink; Dana Dekkers

doi:10.1071/AM24026

REVIEW (Open Access)

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Platypus fyke-netting methods: a review of recommended field protocols and options for assessing population abundance

Melody Serena ^A ^* , Geoff A. Williams ^A , Chris Bloink ^B and Dana Dekkers ^C

+ Author Affiliations

- Author Affiliations

^A Australian Platypus Conservancy, PO Box 115, Campbells Creek, Vic 3451, Australia.

^B Ecology Australia, 2/1 Latitude Boulevard, Thomastown, Vic 3074, Australia.

^C School of Agriculture, Food and Ecosystem Sciences, University of Melbourne, Parkville, Vic 3010, Australia.

^* Correspondence to: platypus.apc@westnet.com.au

Handling Editor: Ross Goldingay

Australian Mammalogy 46, AM24026 https://doi.org/10.1071/AM24026

Submitted: 31 July 2024 Accepted: 26 October 2024 Published: 18 November 2024

© 2024 The Author(s) (or their employer(s)). Published by CSIRO Publishing on behalf of the Australian Mammal Society. This is an open access article distributed under the Creative Commons Attribution-NonCommercial-NoDerivatives 4.0 International License (CC BY-NC-ND)

Abstract

Fyke nets are the preferred type of equipment used for platypus (Ornithorhynchus anatinus) live-trapping surveys in shallow watercourses. However, numerous factors other than abundance may affect the frequency of platypus captures, including when, where and how nets are set, stream discharge and entry into nets by rakali (Hydromys chrysogaster), which create exit holes that are then also available to a platypus. A threefold difference in the mean monthly frequency of platypus captures in fyke nets is also evident across the year. To limit net evasion, it makes sense to reduce net visibility and minimise opportunities for animals to squeeze under, climb over or walk around nets. Time-lapse cameras can also be deployed at fyke-netting sites to estimate how many individuals evade capture. To protect platypus welfare and the welfare of non-target species held in fyke nets, it is important to ensure that captured animals have access to air, to check nets frequently throughout the time they are set and to release bycatch when first encountered. Fyke-netting studies typically generate sparse platypus population data, so care is needed when selecting and interpreting platypus abundance metrics generated through mark–recapture modelling or use of indices.

Keywords: animal welfare, aquatic wildlife survey methods, CPUE, monotreme, net avoidance behaviour, Ornithorhynchidae, platypus population monitoring, population abundance index, time-lapse cameras, trap shyness.

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