Oral Presentation Australian Society for Fish Biology & Australian Freshwater Sciences Society Conference 2026

Does Habitat Degradation Alter Juvenile Fish Connectivity and Habitat Use in Urbanised Coastal Ecosystems. (145298)

William H Knoke 1 , Mitchell Brennan 1 2 , David J Booth 1 2 , Ashley Fowler 3 4 , Francisco Martinez Baena 2
  1. School of Life Sciences, University of technology sydney, Sydney, New South Wales, Australia
  2. Project Restore, Sydney Institute of Marine Science, Sydney, NSW, Australia
  3. School of Life Sciences, University of Technology Sydney, Sydney, NSW, Australia
  4. Department of Primary Industries and Regional Development, Sydney, New South Wales, Australia

 

Background/Aims

Estuarine nursery habitats play a critical role in supporting juvenile marine fishes during vulnerable early life stages, influencing survival, recruitment, and fisheries productivity. In temperate Australia, Pink Snapper (Chrysophrys auratus) utilise habitats such as seagrass and rocky reefs during their early life history, yet fine-scale movement patterns and habitat connectivity within these nursery seascapes remain poorly understood. Habitat degradation, fragmentation, and ongoing restoration initiatives may influence how juvenile fish move among nursery habitats. This study aims to quantify the movement ecology of juvenile C. auratus across a gradient of habitat condition within Sydney Harbour using fine-scale acoustic telemetry VPS arrays.

Methods

Forty-five juvenile C. auratus were captured across six study sites in Sydney Harbour, representing healthy, degraded, and restored nursery habitats, and implanted with Innovasea V7-2x coded acoustic transmitters (7 x 18mm; 0.7g in water; ~221-day battery life) before release at their capture locations. Movements are being monitored using high-resolution VPS acoustic receiver arrays. Tags initially transmit every 60 s (69kHz) to capture fine-scale movements, then reduce transmission frequency to extend battery life and track temporal patterns over the ~221-day deployment.

Results

VPS arrays have been fully operational across all six sites, including healthy, degraded, and restoration seascapes, providing continuous tracking data over the study period. Analyses will quantify home range size, habitat occupancy, residency, mean daily displacement, and cross-habitat movements to compare connectivity patterns across habitat conditions. Initial data show high residency and habitat-specific use, with variability evident across the three treatment groups.

Conclusion

This research will provide insight into the movement ecology of juvenile C. auratus and inform future conservation management planning for urbanised coastal ecosystems. The findings will improve assessment of restoration success and the impact of habitat degradation on connectivity and habitat use in juvenile native fish species within a highly pressured ecosystem.

 

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