Abstract
Context Understanding migratory species’ habitat selection is complicated by variation in movement strategies. Stable-isotope analysis provides a powerful tool to investigate such variation. Aims We used acoustic telemetry and stable-isotope analysis to better understand the movement strategies of Port Jackson sharks. Methods We compared the δ13C and δ15N values of fin tissue from acoustically tracked individuals that undertook three distinct movement strategies. Hierarchical cluster analysis was then used to cluster movement strategies of a larger sample of sharks on the basis of δ13C and δ15N values. Key results Tracked individuals that remained in Jervis Bay were enriched in 13C, compared with those that migrated south after the breeding season. Individuals were assigned to six clusters and δ13C and δ15N values indicated that migrating males and females may utilise different geographical areas or niches during the non-breeding season. Conclusions By using stable isotope analysis and acoustic telemetry, we identified distinct groups of Port Jackson sharks with similar broad-scale movement strategies. Implications These variable movement strategies may lead to different reproductive fitness advantages on an individual and population level, having implications for the broader ecosystem, given the important role mesopredators play in southern reef marine ecosystems.
Funder
Taronga Conservation Society Australia
Macquarie University
Sea World Research and Rescue Foundation
Australian Research Council
Subject
Ecology,Aquatic Science,Ecology, Evolution, Behavior and Systematics,Oceanography