title: Partial migration of grey mullet (Mugil cephalus) on Australia's east coast revealed by otolith chemistry.
abstract: Partial migration affects the ecology and evolution of animal populations, and is an important consideration for the management of harvested species, yet the phenomenon is understudied in fish. We provide the first insights into partially diadromous migration of grey mullet (Mugil cephalus) in Australia by examining the otolith chemistry of old individuals (aged 7-10 years) from two regions on the east coast. Strontium and Barium concentrations were measured across the otolith using laser ablation inductively coupled plasma mass spectrometry (LA-ICP-MS) and indicated considerable diversity in migratory histories among individuals. Only 15% of individuals made repeated movements from estuaries to the marine environment, consistent with the annual spawning run in the region. The remainder either made irregular movements between salinity environments (70%), or resided in estuaries or fresh water for their entire life following the early juvenile stage (15%). The patterns are consistent with 'skipped spawning' partial migration, where a proportion of the mature population forgoes spawning each year. If confirmed, the behavior may afford the east coast population of M. cephalus some resilience to fishing pressure on the annual spawning run.
authors.affiliation: New South Wales Department of Primary Industries, Sydney Institute of Marine Science, Mosman, NSW 2088, Australia. Electronic address: ashley.fowler@dpi.nsw.gov.au.
authors.forename: Ashley M
authors.initials: AM
authors.lastname: Fowler
authors.affiliation: Fish Ecology Laboratory, School of Life Sciences, University of Technology Sydney, Broadway, NSW 2007, Australia.
authors.forename: Shannen M
authors.initials: SM
authors.lastname: Smith
authors.affiliation: Fish Ecology Laboratory, School of Life Sciences, University of Technology Sydney, Broadway, NSW 2007, Australia.
authors.forename: David J
authors.initials: DJ
authors.lastname: Booth
authors.affiliation: New South Wales Department of Primary Industries, Sydney Institute of Marine Science, Mosman, NSW 2088, Australia.
authors.forename: John
authors.initials: J
authors.lastname: Stewart
mesh_terms: D025041:Animal Migration; D000818:Animals; D001315:Australia; D010037:Otolithic Membrane / Q000737:chemistry*; D023701:Smegmamorpha / Q000502:physiology*
keywords: Catadromy; Diadromy; Mugil cephalus; Mullet; Otolith chemistry; Partial migration; Skipped spawning