The objective of the Greater Brisbane Fish Barrier Prioritisation (GBFBP) was to identify and assess the large number of man-made barriers that prevent, delay, or obstruct fish migration in the Greater Brisbane (GB) region.
Fish barriers identified through this process were ranked in order of priority, accounting for the cumulative impacts barriers have on the environment, fisheries resources, economy, and the local community.
Download the Greater Brisbane Fish Barrier Prioritisation Report
Fish migration is an essential life history adaptation utilised by many freshwater fish species in the GB region.
Migration strategies between key habitats have evolved for a variety of reasons, including feeding and reproduction purposes, predator avoidance, nursery habitat utilisation, and maintaining genetic diversity.
Barriers preventing connectivity in the GB region impact fisheries’ productivity and create environmental conditions favourable for invasive pest fish species. Significantly, almost half of the GB freshwater fish species undertake life-cycle dependant movements between estuarine and freshwater environments.
Remediating barriers and maintaining connectivity between saltwater and freshwater is therefore critical to ensure freshwater fish community condition and to improve overall aquatic ecosystem health. This project aimed to address such issues through identifying, ranking, and remediating fish passage barriers throughout the GB region.
The overall aims of this project were to:
1. Systematically identify all potential barriers to fish passage in the GB region.
2. Undertake catchment-scale GIS analysis of biological, geographic and environmental characteristics associated with each potential barrier to produce a prioritised list for ground-truthing, i.e. visit the most important potential barriers first.
3. Perform fine-scale, site specific barrier assessment to validate, score and rank priority barriers based on passability, configuration, in-stream habitat availability and flow conditions.
4. Further refine and prioritise barriers based on economic, social and fisheries productivity criteria.
5. Produce a list of the top 50 priority ranked fish barriers in the GB region showing remediation options and indicative costs
6. Facilitate the adoption of fish barrier remediation by Local Governments and Natural Resource Managers
a. Construction of appropriately designed fishways (fish ladders) at several high priority sites in partnership with respective Councils
b. Evaluation monitoring to assess remediation success
Fish Barriers
The fish barrier prioritisation process involved identifying potential barriers using high resolution aerial imagery across the GB region. In total, 13,629 potential barriers were identified in the project area (3,582 km2) at a rate of 3.8 potential barriers per km2. Geographic Information System (GIS) software was then applied to rapidly assess and prioritise the high number of potential barriers using a collective optimisation rank-and-score approach. Importantly, key socio-economic flow-on benefits of improving aquatic ecosystem connectivity were considered i.e. the degree to which barrier remediation may increase fisheries productivity and/or conserve vulnerable fish species, e.g. jungle perch.
In many parts of the world, remediation of man-made barriers with appropriately designed fishways (fish ladders) is one of the most successful management tools utilised by government agencies and natural resource management groups to help restore populations of fish impacted by barriers. Objectively choosing the ‘right’ barriers to remediate in order to obtain the greatest benefits requires a holistic prioritisation process. In this prioritisation assessment, the process guided the authors to groundtruthing the top priority potential barriers in order of importance. The resultant GBFBP report and associated priority ranked fish barrier list will assist natural resource managers and decision makers in determining where best to allocate funding opportunities to ensure the greatest environmental and socio-economic outcomes for the GB region.
Conclusion
13,629 potential barriers within the GB region were identified and refined to a list of the highest priority sites within the region (top 55 ranked fish barriers). The priority ranked sites represent the greatest return in terms of ecological restoration with the least financial expenditure. By remediating fish passage at these sites, extensive areas of fish habitat will become accessible to many socio-economically important migratory fish species. This will ensure the sustainability of fish populations and improve aquatic ecosystem health in many of the region’s waterways, while investing rehabilitation funds in the most efficient manner.
Results – Top ranking fish barriers in the Greater Brisbane region
Complete list of the top 55 ranking fish barriers in south east Queensland
This report forms part of the overarching project Re-Connecting Aquatic Habitats Across the Greater Brisbane Urban Area, which was commissioned by the Federal Government under the Targeted Area Grants program via Reef Catchments Limited (RCL) Natural Resource Management (NRM) group.