Fish case studies

NSW has a statewide monitoring program using baited remote underwater videos to assess fish communities on our rocky reefs. NEAP will expand this program to focus on new locations in estuaries and increase sampling density and times. It will directly support the NEAP Estuarine Monitoring project through focal case studies that increase our understanding of how floods may impact estuarine fish assemblages in particular locations.

A paper "Quantifying the effects of extreme flooding on coastal reef fishes" provides initial findings.

Estuary bed and biological monitoring in NSW northern rivers

This project focused on hydroacoustic surveys of the Richmond, Clarence, Macleay and Sandon rivers. Hydroacoustic surveys use echosounder machines to generate sound waves to explore underwater environments. DPIRD Fisheries and InfoFish used this method to assess fish populations (biomass), habitat condition and changes to the estuary bed (bathymetry). Repeated surveys established a baseline for understanding how fish populations respond to post-flood environmental changes.

Surveys covered more than 8,000 hectares of river and estuary habitat including deep and shallow water sites in the upper, middle and lower river reaches. Detailed maps of water depth, bank slope and bottom type were created.

Fish detections were combined with habitat information to assess relationships between fish distribution and environmental factors such as depth, slope, substrate type and position within the water column.

Because these surveys were designed to provide repeatable monitoring data, they are capable of detecting changes in fish abundance and habitat use over time. This will help us better understand responses of fish and estuarine environments to future flood events and habitat rehabilitation activities.