A Review of Giant Mud Crab Scylla serrata (Family Portunidae) Spawning Migration: The Lost Link in the Species’ Life History

Abstract

Spawning migration is a behavioural trait observed in various aquatic animals. Understanding this behaviour is vital for fisheries management and the sustainability of harvested populations. Ovigerous female Giant Mud Crabs Scylla serrata (Forskål, 1775), a valuable portunid in the Indo-West Pacific region, have been observed to undertake spawning migrations in some regions. As this stage of the species’ life history remains poorly understood, this systematic review aimed to critically analyse the literature on Giant Mud Crabs, focused on their spawning migrations. We also investigated methods applied to studying the movement ecology of other crab species to identify techniques that could be used to address the Giant Mud Crab spawning migration. Although ecological studies into this species have increased recently, the scarcity of knowledge on female Giant Mud Crab behaviour between mating and spawning remains a constraint. The direct study of wild ovigerous females remains a challenge, as they are rarely caught in estuaries where commercial and recreational crab pots are deployed. Overall, the review identified mark-recapture (25%) and acoustic telemetry (25%) were the most frequently employed methods utilised to study the movement ecology of at least 21 crab families, predominantly the family Portunidae. We highlighted five approaches, including mark-recapture, acoustic telemetry, Pop-up Satellite tags, zooplankton surveys and numerical modelling used in crab research that could be applied to track ovigerous female Giant Mud Crabs during the spawning migration and discussed their respective strengths and weaknesses. A combination of methods and possible collaboration with citizen science programs was identified as an appropriate strategy to elucidate the Giant Mud Crabs spawning migration.