Movement of an exploited coral reef teleost across spatial and temporal scales
Release of acoustically tagged redthroat emperor
My research focused on gaining a better understanding of movement patterns of an exploited reef fish, redthroat emperor (Lethrinus miniatus) across over multiple temporal scales (minutes to years) and spatial scales (metres to 100s of kilometres).
Redthroat emperor is important to the fisheries of Australia, Japan, New Caledonia and Tonga, with the largest fishery on Great Barrier Reef (GBR), Australia. Despite this, little information on their movement was previously available since conventional tagging efforts have yielded generally low numbers of recaptures. Most emperors are thought to be sedentary as adults with small home ranges, yet some individuals of this species have displayed large-scale movement. It is uncertain whether long-distance movement is typical, or a direct response to changes in the environment. Since the movement of fishes defines their distribution and abundance, my research provided important information for assessments and designing management strategies (e.g. marine park zoning) for exploited fish populations. Similarly, understanding how this species moves with changes in environmental conditions was important.
Thus, my project used two complimentary methods to investigate movement: acoustic telemetry to examine reef-scale movement; and otolith (fish ear bone) microchemistry to examine the potential for broad-scale migration along the GBR. My research questions included: a) How does redthroat emperor use space - both horizontal activity space and depth? b) What environmental conditions are responsible for driving movement patterns? c) Do redthroat emperor undergo long-distance movements along the Great Barrier Reef?
These two approaches provided information beneficial to the management of emperors in tropical fisheries and are applicable to other species.
My supervisors were: Michelle Heupel (AIMS/JCU), Colin Simpfendorfer (JCU), Ashley Williams (SPC/JCU) & Stephen Sutton (JCU).