Fish Barrier Prioritisation (Landscape Scale Coastal, no economic analysis)

The objective of this method is to identify and assess anthropogenic physical barriers (biophysical, such as weed chokes, are not considered) that prevent, delay, or obstruct fish migration in coastal catchments. Fish barriers identified through this process are ranked in order of priority, accounting for the cumulative impacts barriers have on the environment, fisheries resources, the economy, and the local community. Fisheries productivity benefits of barrier remediation are also considered.

This method systematically identifies all potential physical barriers to fish passage in a study area. The top ranked barriers in the study areas have remediation options costed to facilitate adoption of fish barrier remediation by local governments and natural resource management (NRM) groups. A holistic prioritisation process is used to objectively choose barriers to remediate to obtain the greatest benefits. This holistic process assists decisionmakers in determining where to best allocate funding opportunities to ensure the greatest environmental and socioeconomic outcomes for the study area. The assessment incorporates the impact on fish movement, location in the catchment (stream order) and surrounding land use in the first stage. The second stage incorporates an assessment of habitat condition and the third stage incorporates the social, conservation, and fisheries productivity benefits of barrier remediation at each site. This method does not include an economic assessment, see Fish Barrier Prioritisation (Landscape Scale/Coastal, with economic analysis) for the method that includes an economic assessment.

Barriers to fish passage such as dams, weirs, causeways, culverts, earthen bunds and floodgates can impact the health of river systems by altering natural flow regimes, and causing impassable barriers to aquatic fauna, especially fish. High value fish species, both ecologically and economically, are in decline due to barriers impeding strict migratory life-cycle strategies (i.e. feeding, recruitment) which requires unimpeded access between habitats (i.e. between inland freshwater habitats and estuary/marine habitats).

This method’s objective is to identify and assess physical anthropogenic barriers that prevent, delay, or obstruct fish migration in coastal catchments. Fish barriers identified through this process are ranked in order of priority, accounting for the cumulative impacts barriers have on the environment, fisheries resources, economy, and local community. The aim is to remediate barriers preventing connectivity, and this method assists decision makers in choosing which barriers to focus on, because there are large numbers of barriers in many coastal catchments that outweigh the resources available to remediate.

This method identifies and prioritises barriers through 3 major stages.

Stage 1. Catchment Scale: GIS Analysis – Spatial & Temporal Habitat Characteristics

The first stage systematically identifies all potential barriers to fish passage in the study area. This is done through a desktop, catchment-scale GIS analysis of biological, geographic and environmental characteristics associated with each potential barrier to produce a prioritised list for ground-truthing.

Stage 2 – Fine Scale: Site- Specific Ecological Assessment (includes field validation)

The second stage performs a fine-scale, site specific barrier assessment to validate, score and rank priority barriers based on passability, configuration, in-stream habitat availability and flow conditions.

Stage 3 – Analysis

The third stage further refines and prioritises barriers based on social, conservation, and fisheries productivity benefits.

The top ranked fish barriers, depending on the area (can vary from 20 to 50), are listed with remediation options and indicative costs. This list is then available for adoption by State and local governments and natural resource management groups. The holistic prioritisation process makes this selection effective and applicable straightaway.

Stage 1 Catchment Scale: GIS Analysis – Spatial & Temporal Habitat Characteristics

• Stream Hierarchy
• Number of potential barriers downstram
• Upstream Catchment Excluded by the Potential Barrier
• Distance to next barrier upstream
• Catchment condition (% Intensive land use)
• Distance to estuary

Stage 2 Fine Scale: Site- Specific Ecological Assessment

• Barrier type and passability
• Stream condition
• Habitat for Migratory Fish Species Upstream of Barrier Site

  Stage 3 Analysis

• Site access
• Conservation significance
• Fisheries productivity and economic benefits

• Locational and spatial data for barriers (e.g. bridges, culverts, road crossings, infrastructure)
• High quality imagery (satellite/drone)
• Stream ordered drainage network (e.g. Strahler stream order and gradient) and/or Queensland waterways for waterway barrier works (layer by Fisheries QLD)
• Land us (Queensland Land Use Mapping Program (QLUMP))
• Barrier types and number
• Riparian condition
• Instream habitat condition
• Conservation significance
• Habitat suitability
• Streamflow classification (e.g. water supply permanence)

Expert knowledge of riverine fauna ecology including life cycle and habitat requirements. Field assessment skills, and GIS data analysis skills. Knowledge of fisheries in the study area, including any listing under environmental legislation. Research skills to get baseline information about fish species in the study area.

Geographic Information System for barrier identification and prioritisation.
High quality imagery (satellite/drone)
Species lists
Spatial data

Stage 1 Desktop Analysis: All potential physical barriers in the study area are identified and a dataset is produced with a unique geo-referenced identification number. A prioritised list for ground-truthing (field assessment) is produced.

Stage 2 Field Assessment: A second list of physical barriers is produced, from refining the list in Stage 1. This list scores physical barriers according ecological criteria and contains site specific information about the barrier.

Stage 3 Analysis: A third list of physical barriers is produced from refining the list in Stage 2. This stage scores physical barriers based on social, conservation, and fisheries productivity criteria. The scores are collated from each stage to identify the top-ranked (highest score) barrier in the study area.

A final list of the top ranked fish barriers in the study area is produced, which also show remediation options (fishway options) and indicative costs.

• Input to investment strategies for fish barrier remediation works
• Threat and risk identification
• Decision support
• Inform priorities of management interventions required to reduce risks to ecosystems from different threats and improve ecosystem condition

Designed for state, or local government agencies, water utilities, and natural resource management groups.

• Assesses one of the key threats to aquatic ecosystems – loss of connectivity from headwaters to estuary
• Accounts for ecological, social, and economic considerations
• Risk based approach allows for targeted prioritisation of barriers
• Informs management interventions at site scale despite being catchment scale assessment
• Repeated assessments can account for changes in the catchment area and refine rankings
• Adaptive monitoring and management

• Method applies to fish species only
• Instream habitat condition assessment plays a minor role in rankings and finer scale pressures may not be considered
• Focuses on migration and not all fish movement
• Conservation significance ranks common or abundant species low, common species may still be impacted by barriers to fish passage

2021 Fish Barrier Prioritisation – Mackay Whitsunday Region

Fish Barrier Prioritisation – Murray and Lower Herbert Rivers

This page should be cited as:

Department of Environment, Science and Innovation, Queensland (2022) Fish Barrier Prioritisation (Landscape Scale Coastal, no economic analysis), WetlandInfo website, accessed 18 March 2024. Available at: https://wetlandinfo.des.qld.gov.au/wetlands/resources/tools/assessment-search-tool/fish-barrier-prioritisation-landscape-scale-coastal-no-economic-analysis/