Crabs go with the flow: declining conductivity and cooler temperatures trigger spawning migrations for female Giant Mud Crabs (Scylla serrata) in subtropical estuaries

Daniel E. Hewitt*, Yuri Niella, Daniel D. Johnson, Iain M. Suthers, Matthew D. Taylor

*Corresponding author for this work

    Research output: Contribution to journalArticlepeer-review

    11 Citations (Scopus)
    29 Downloads (Pure)

    Abstract

    Spawning is a key life history event for aquatic species that can be triggered by environmental signals. For estuarine-dependent species, the timing of such triggers can be important for determining future patterns in recruitment. Here, we used acoustic telemetry to identify the potential drivers of spawning migration in female Giant Mud Crabs (Scylla serrata). Eighty-nine mature female crabs were tagged in two subtropical south-east Australian estuaries, the Clarence River (~ 29.4°S) and Kalang River (~ 30.5°S), during the summer spawning season (November–June) over two years (2018/19 and 2020/21), and their movements were monitored for up to 68 d, alongside high-resolution environmental data. Crabs were considered to have ‘successfully’ migrated if they were detected at the mouth of the estuary, a behaviour exhibited by 52% of tagged crabs. The highest probability of migration was associated with relatively low temperatures (< 22 °C) and when conductivity rapidly declined (< -10 mS cm−1 d−1) following heavy rainfall. Furthermore, migration coincided with larger tides associated with the new and full moon, and following heavy rainfall, which may aid rapid downstream migration. Oceanic detections of 14 crabs (30% of ‘successful’ migrators) showed that once crabs left estuaries they migrated north. These patterns show that variability in environmental triggers for spawning migrations may contribute to interannual variation in spawning patterns, which may in turn impact fisheries productivity in this region.

    Original languageEnglish
    Pages (from-to)2166-2180
    Number of pages15
    JournalEstuaries and Coasts
    Volume45
    Issue number7
    Early online date1 Mar 2022
    DOIs
    Publication statusPublished - Nov 2022

    Bibliographical note

    Copyright the Author(s) 2022. Version archived for private and non-commercial use with the permission of the author/s and according to publisher conditions. For further rights please contact the publisher.

    Keywords

    • Acoustic telemetry
    • Crustacean
    • Fisheries productivity
    • Integrated Marine Observing System
    • Movement
    • Recruitment variability

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