Barramundi (Lates calcarifer) often migrate from marine to fresh water as juveniles. In March 201... more Barramundi (Lates calcarifer) often migrate from marine to fresh water as juveniles. In March 2018a relatively large number of small juveniles (<100mm) were recorded moving through a fishway on a tidal interface barrier in central Queensland, Australia. This is in contrast to the few documented observations of transitional movements, which involved mostly larger juveniles (250–400mm).
This report has been commissioned by Reef Catchments Limited (RCL) Natural Resource Management (N... more This report has been commissioned by Reef Catchments Limited (RCL) Natural Resource Management (NRM) group to identify and prioritise the large number of anthropogenic barriers that prevent, delay or obstruct fish migration in the Mackay Whitsundays (MW) region. The following report comprises a three stage fish barrier prioritisation process (FBPP) that comprehensively ranks barriers to fish passage based on a number of key biological, geographic and economic considerations.
The prioritisation process initially utilised Geographic Information System (GIS) software to rapidly assess thousands of potential barriers before undertaking a collective optimisation and rank-and-score approach. Importantly, key socio-economic ‘flow on’ benefits of improving aquatic ecosystem connectivity have been considered i.e. increasing fisheries productivity and conserving vulnerable fish species.
Fish migration is an essential life history adaptation utilised by many MW fish species. Migration strategies between key habitats have evolved for a variety of reasons, including for feeding and reproduction purposes, to avoid predators, to utilise nursery areas and maintain genetic diversity.
Barriers preventing connectivity in the MW region impact fisheries’ productivity and create environmental conditions favourable for invasive fish species. Significantly, approximately 48% of MW region fish species undertake ontogenetic shifts in habitat use between near-shore marine and freshwater environments. Low transparency barriers located on high ordered streams close to the tidal interface have the greatest impact, preventing and impeding juvenile diadromous species from undertaking important longitudinal and lateral life-cycle dependant migrations into critical nursery habitats.
Key socio-economic species such as barramundi, sea mullet, mangrove jack, jungle perch, tarpon and long-finned eels are significantly affected. Barriers in the MW region impact freshwater fish communities, affect aquatic ecosystem resilience and reduce the vicarious values the local community places on waterways flowing into the Great Barrier Reef Marine Park.
In many parts of the world remediation of barriers with appropriately designed fishways is one of the most successful management tools utilised by government agencies and natural resource management groups to help reduce the impacts of barriers. However, objectively choosing the ‘right’ barriers to remediate in order to obtain the greatest benefits requires a holistic prioritisation process. The following three stage MW barrier prioritisation process achieves this by investigating the cumulative impacts barriers have on the environment, fishery, economy and local community. The resultant priority ranked list will assist natural resource managers and decision makers in determining where best to allocate limited funding opportunities to ensure the greatest environmental and socio-economic outcomes for the MW region.
A 30-mm juvenile barramundi (Fig. 1a) was captured after successfully ascending a cone ramp fishw... more A 30-mm juvenile barramundi (Fig. 1a) was captured after successfully ascending a cone ramp fishway on a tidal interface barrier (-21.5250388S, 149.2647118E) in the Rocky Dam Catchment, central Queensland, Australia. The barrier comprises an extensive earth bund that separates upper-tidal habitat from a modified freshwater wetland. This type of wetland, frequently termed ponded pastures, is common in north-eastern Australia. The fishway was monitored for six days, from 25 to 30 March 2018. Fish were captured in a meshed box trap placed above the top ridge (Fig. 1b). The 30-mm barramundi was one of 43 captured in a 24-h set, overnight on 29/30 March 2018. These fish measured 30–101 mm total length, with an average size of 45 mm. In the four days leading to this set only six barramundi were recoded moving through the fishway; three of these were captured during a 5-h set on 29 March. Fish captured during the daytime set on 29 March measured 36–44 mm and those captured on preceding days measured 90–173 mm.Juvenile barramundi of this size range fall into the 0þ age class (Davis and Kirkwood 1984). While there are some documented observations of larger juveniles (250–400 mm) in this age class undertaking this transitional migration (e.g. Stuart and Mallen-Cooper 1999), no records could be found of smaller juveniles (<50 mm) undertaking such movements. The proximity of the wetlands to postlarval supralittoral habitat (Russell and Garrett 1983) may indicate opportunistic movements, or some other cue (e.g. chemical) may be attracting these smaller fish into the wetlands. Notably, the increased catch rates coincided with building tides, which the fish may have used to exit supralittoral pools and/or aid their movement upstream. Our observations highlight the importance of connectivity restoration, particularly on tidal interface barriers where juvenile diadromous fish may be precluded from important nursery habitats.
This report forms part of the overarching project ‘Re-Connecting Aquatic Habitats Across the Grea... more 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. The objective of the Greater Brisbane Fish Barrier Prioritisation (GBFBP) was to identify and assess the large number of anthropogenic 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 local community. 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 ontogenetic shifts in habitat use between estuarine and freshwater environments. Remediating barriers and maintaining connectivity between saltwater and freshwater is therefore critical to ensuring freshwater fish community condition and improving overall aquatic ecosystem health. This project aimed to address such issues, through identifying, ranking and remediating fish passage barriers throughout the GB region.
Explicitly, the overall aims of the 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 at several high priority sites in partnership with respective Councils b. Evaluation monitoring to assess remediation success c. Field day – South-East Queensland fish passage field trip
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 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. The GBFBP was also used to guide the remediation of several priority fish barrier sites as part of the overarching project. Fish barrier sites were chosen based on priority ranking and available resources. Five fishways were designed, constructed and monitored by Catchment Solutions (CS) between 2016 and 2017, and delivery of individual fishway projects were undertaken in partnership with each respective Local Government (LG) (Table A). Rock-ramp fishways (RRF) were chosen as the preferred design option at all sites due to their ability to pass weaker swimming juvenile and small bodied species, their natural appearance, pool roughness (creating micro-eddies) and minimal cost outlay when compared to highly engineered, smooth-sided fishways such as vertical-slot fishways. Rock-ramp fishways were constructed on the:
Bremer River (Berrys Weir - ranked 7th), South Pine River (Leitchs Crossing - ranked 11th), Hilliards Creek (Hilliards Weir - ranked equal 36th) and Slacks Creek (Paradise Road overpass - ranked equal 36th). Due to site constraints, a horizontal culvert baffle fishway was constructed in addition to the rock-ramp fishway at Paradise Road on Slacks Creek.
Fishway monitoring was undertaken to evaluate the success of each fishway at facilitating fish passage for the entire fish community. Results showed that all expected juvenile diadromous and small bodied species were able to ascend the fishways. The 2.4 m high, 90 m long, 33 ridge Bremer River partial width rock-ramp fishway recorded the highest numbers and diversity of fish, with over 16,000 individuals recorded in just over four days of monitoring at a catch rate of 4,075 fish per day. The median size of all fish captured was just 34 mm, highlighting the success of the fishway at passing weaker swimming juveniles and small bodied species. Notable captures included the migration of key juvenile diadromous species, such as sea mullet, freshwater mullet and bullrout, which represented catch rates of 316, 266, and 27 individuals per day respectively. The success of each fishway project can be directly attributed to the strong working partnerships developed between CS and each LG to remediate priority fish barriers and deliver significant aquatic connectivity remediation outcomes for the benefit of the environment and local communities.
Barramundi (Lates calcarifer) often migrate from marine to fresh water as juveniles. In March 201... more Barramundi (Lates calcarifer) often migrate from marine to fresh water as juveniles. In March 2018a relatively large number of small juveniles (<100mm) were recorded moving through a fishway on a tidal interface barrier in central Queensland, Australia. This is in contrast to the few documented observations of transitional movements, which involved mostly larger juveniles (250–400mm).
This report has been commissioned by Reef Catchments Limited (RCL) Natural Resource Management (N... more This report has been commissioned by Reef Catchments Limited (RCL) Natural Resource Management (NRM) group to identify and prioritise the large number of anthropogenic barriers that prevent, delay or obstruct fish migration in the Mackay Whitsundays (MW) region. The following report comprises a three stage fish barrier prioritisation process (FBPP) that comprehensively ranks barriers to fish passage based on a number of key biological, geographic and economic considerations.
The prioritisation process initially utilised Geographic Information System (GIS) software to rapidly assess thousands of potential barriers before undertaking a collective optimisation and rank-and-score approach. Importantly, key socio-economic ‘flow on’ benefits of improving aquatic ecosystem connectivity have been considered i.e. increasing fisheries productivity and conserving vulnerable fish species.
Fish migration is an essential life history adaptation utilised by many MW fish species. Migration strategies between key habitats have evolved for a variety of reasons, including for feeding and reproduction purposes, to avoid predators, to utilise nursery areas and maintain genetic diversity.
Barriers preventing connectivity in the MW region impact fisheries’ productivity and create environmental conditions favourable for invasive fish species. Significantly, approximately 48% of MW region fish species undertake ontogenetic shifts in habitat use between near-shore marine and freshwater environments. Low transparency barriers located on high ordered streams close to the tidal interface have the greatest impact, preventing and impeding juvenile diadromous species from undertaking important longitudinal and lateral life-cycle dependant migrations into critical nursery habitats.
Key socio-economic species such as barramundi, sea mullet, mangrove jack, jungle perch, tarpon and long-finned eels are significantly affected. Barriers in the MW region impact freshwater fish communities, affect aquatic ecosystem resilience and reduce the vicarious values the local community places on waterways flowing into the Great Barrier Reef Marine Park.
In many parts of the world remediation of barriers with appropriately designed fishways is one of the most successful management tools utilised by government agencies and natural resource management groups to help reduce the impacts of barriers. However, objectively choosing the ‘right’ barriers to remediate in order to obtain the greatest benefits requires a holistic prioritisation process. The following three stage MW barrier prioritisation process achieves this by investigating the cumulative impacts barriers have on the environment, fishery, economy and local community. The resultant priority ranked list will assist natural resource managers and decision makers in determining where best to allocate limited funding opportunities to ensure the greatest environmental and socio-economic outcomes for the MW region.
A 30-mm juvenile barramundi (Fig. 1a) was captured after successfully ascending a cone ramp fishw... more A 30-mm juvenile barramundi (Fig. 1a) was captured after successfully ascending a cone ramp fishway on a tidal interface barrier (-21.5250388S, 149.2647118E) in the Rocky Dam Catchment, central Queensland, Australia. The barrier comprises an extensive earth bund that separates upper-tidal habitat from a modified freshwater wetland. This type of wetland, frequently termed ponded pastures, is common in north-eastern Australia. The fishway was monitored for six days, from 25 to 30 March 2018. Fish were captured in a meshed box trap placed above the top ridge (Fig. 1b). The 30-mm barramundi was one of 43 captured in a 24-h set, overnight on 29/30 March 2018. These fish measured 30–101 mm total length, with an average size of 45 mm. In the four days leading to this set only six barramundi were recoded moving through the fishway; three of these were captured during a 5-h set on 29 March. Fish captured during the daytime set on 29 March measured 36–44 mm and those captured on preceding days measured 90–173 mm.Juvenile barramundi of this size range fall into the 0þ age class (Davis and Kirkwood 1984). While there are some documented observations of larger juveniles (250–400 mm) in this age class undertaking this transitional migration (e.g. Stuart and Mallen-Cooper 1999), no records could be found of smaller juveniles (<50 mm) undertaking such movements. The proximity of the wetlands to postlarval supralittoral habitat (Russell and Garrett 1983) may indicate opportunistic movements, or some other cue (e.g. chemical) may be attracting these smaller fish into the wetlands. Notably, the increased catch rates coincided with building tides, which the fish may have used to exit supralittoral pools and/or aid their movement upstream. Our observations highlight the importance of connectivity restoration, particularly on tidal interface barriers where juvenile diadromous fish may be precluded from important nursery habitats.
This report forms part of the overarching project ‘Re-Connecting Aquatic Habitats Across the Grea... more 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. The objective of the Greater Brisbane Fish Barrier Prioritisation (GBFBP) was to identify and assess the large number of anthropogenic 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 local community. 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 ontogenetic shifts in habitat use between estuarine and freshwater environments. Remediating barriers and maintaining connectivity between saltwater and freshwater is therefore critical to ensuring freshwater fish community condition and improving overall aquatic ecosystem health. This project aimed to address such issues, through identifying, ranking and remediating fish passage barriers throughout the GB region.
Explicitly, the overall aims of the 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 at several high priority sites in partnership with respective Councils b. Evaluation monitoring to assess remediation success c. Field day – South-East Queensland fish passage field trip
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 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. The GBFBP was also used to guide the remediation of several priority fish barrier sites as part of the overarching project. Fish barrier sites were chosen based on priority ranking and available resources. Five fishways were designed, constructed and monitored by Catchment Solutions (CS) between 2016 and 2017, and delivery of individual fishway projects were undertaken in partnership with each respective Local Government (LG) (Table A). Rock-ramp fishways (RRF) were chosen as the preferred design option at all sites due to their ability to pass weaker swimming juvenile and small bodied species, their natural appearance, pool roughness (creating micro-eddies) and minimal cost outlay when compared to highly engineered, smooth-sided fishways such as vertical-slot fishways. Rock-ramp fishways were constructed on the:
Bremer River (Berrys Weir - ranked 7th), South Pine River (Leitchs Crossing - ranked 11th), Hilliards Creek (Hilliards Weir - ranked equal 36th) and Slacks Creek (Paradise Road overpass - ranked equal 36th). Due to site constraints, a horizontal culvert baffle fishway was constructed in addition to the rock-ramp fishway at Paradise Road on Slacks Creek.
Fishway monitoring was undertaken to evaluate the success of each fishway at facilitating fish passage for the entire fish community. Results showed that all expected juvenile diadromous and small bodied species were able to ascend the fishways. The 2.4 m high, 90 m long, 33 ridge Bremer River partial width rock-ramp fishway recorded the highest numbers and diversity of fish, with over 16,000 individuals recorded in just over four days of monitoring at a catch rate of 4,075 fish per day. The median size of all fish captured was just 34 mm, highlighting the success of the fishway at passing weaker swimming juveniles and small bodied species. Notable captures included the migration of key juvenile diadromous species, such as sea mullet, freshwater mullet and bullrout, which represented catch rates of 316, 266, and 27 individuals per day respectively. The success of each fishway project can be directly attributed to the strong working partnerships developed between CS and each LG to remediate priority fish barriers and deliver significant aquatic connectivity remediation outcomes for the benefit of the environment and local communities.
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The prioritisation process initially utilised Geographic Information System (GIS) software to rapidly assess thousands of potential barriers before undertaking a collective optimisation and rank-and-score approach. Importantly, key socio-economic ‘flow on’ benefits of improving aquatic ecosystem connectivity have been considered i.e. increasing fisheries productivity and conserving vulnerable fish species.
Fish migration is an essential life history adaptation utilised by many MW fish species. Migration strategies between key habitats have evolved for a variety of reasons, including for feeding and reproduction purposes, to avoid predators, to utilise nursery areas and maintain genetic diversity.
Barriers preventing connectivity in the MW region impact fisheries’ productivity and create environmental conditions favourable for invasive fish species. Significantly, approximately 48% of MW region fish species undertake ontogenetic shifts in habitat use between near-shore marine and freshwater environments. Low transparency barriers located on high ordered streams close to the tidal interface have the greatest impact, preventing and impeding juvenile diadromous species from undertaking important longitudinal and lateral life-cycle dependant migrations into critical nursery habitats.
Key socio-economic species such as barramundi, sea mullet, mangrove jack, jungle perch, tarpon and long-finned eels are significantly affected. Barriers in the MW region impact freshwater fish communities, affect aquatic ecosystem resilience and reduce the vicarious values the local community places on waterways flowing into the Great Barrier Reef Marine Park.
In many parts of the world remediation of barriers with appropriately designed fishways is one of the most successful management tools utilised by government agencies and natural resource management groups to help reduce the impacts of barriers. However, objectively choosing the ‘right’ barriers to remediate in order to obtain the greatest benefits requires a holistic prioritisation process. The following three stage MW barrier prioritisation process achieves this by investigating the cumulative impacts barriers have on the environment, fishery, economy and local community. The resultant priority ranked list will assist natural resource managers and decision makers in determining where best to allocate limited funding opportunities to ensure the greatest environmental and socio-economic outcomes for the MW region.
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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 ontogenetic shifts in habitat use between estuarine and freshwater environments. Remediating barriers and maintaining connectivity between saltwater and freshwater is therefore critical to ensuring freshwater fish community condition and improving overall aquatic ecosystem health. This project aimed to address such issues, through identifying, ranking and remediating fish passage barriers throughout the GB region.
Explicitly, the overall aims of the 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 at several high priority sites in partnership with respective Councils
b. Evaluation monitoring to assess remediation success
c. Field day – South-East Queensland fish passage field trip
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 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.
The GBFBP was also used to guide the remediation of several priority fish barrier sites as part of the overarching project. Fish barrier sites were chosen based on priority ranking and available resources. Five fishways were designed, constructed and monitored by Catchment Solutions (CS) between 2016 and 2017, and delivery of individual fishway projects were undertaken in partnership with each respective Local Government (LG) (Table A). Rock-ramp fishways (RRF) were chosen as the preferred design option at all sites due to their ability to pass weaker swimming juvenile and small bodied species, their natural appearance, pool roughness (creating micro-eddies) and minimal cost outlay when compared to highly engineered, smooth-sided fishways such as vertical-slot fishways. Rock-ramp fishways were constructed on the:
Bremer River (Berrys Weir - ranked 7th),
South Pine River (Leitchs Crossing - ranked 11th),
Hilliards Creek (Hilliards Weir - ranked equal 36th) and
Slacks Creek (Paradise Road overpass - ranked equal 36th). Due to site constraints, a horizontal culvert baffle fishway was constructed in addition to the rock-ramp fishway at Paradise Road on Slacks Creek.
Fishway monitoring was undertaken to evaluate the success of each fishway at facilitating fish passage for the entire fish community. Results showed that all expected juvenile diadromous and small bodied species were able to ascend the fishways. The 2.4 m high, 90 m long, 33 ridge Bremer River partial width rock-ramp fishway recorded the highest numbers and diversity of fish, with over 16,000 individuals recorded in just over four days of monitoring at a catch rate of 4,075 fish per day. The median size of all fish captured was just 34 mm, highlighting the success of the fishway at passing weaker swimming juveniles and small bodied species. Notable captures included the migration of key juvenile diadromous species, such as sea mullet, freshwater mullet and bullrout, which represented catch rates of 316, 266, and 27 individuals per day respectively. The success of each fishway project can be directly attributed to the strong working partnerships developed between CS and each LG to remediate priority fish barriers and deliver significant aquatic connectivity remediation outcomes for the benefit of the environment and local communities.
The prioritisation process initially utilised Geographic Information System (GIS) software to rapidly assess thousands of potential barriers before undertaking a collective optimisation and rank-and-score approach. Importantly, key socio-economic ‘flow on’ benefits of improving aquatic ecosystem connectivity have been considered i.e. increasing fisheries productivity and conserving vulnerable fish species.
Fish migration is an essential life history adaptation utilised by many MW fish species. Migration strategies between key habitats have evolved for a variety of reasons, including for feeding and reproduction purposes, to avoid predators, to utilise nursery areas and maintain genetic diversity.
Barriers preventing connectivity in the MW region impact fisheries’ productivity and create environmental conditions favourable for invasive fish species. Significantly, approximately 48% of MW region fish species undertake ontogenetic shifts in habitat use between near-shore marine and freshwater environments. Low transparency barriers located on high ordered streams close to the tidal interface have the greatest impact, preventing and impeding juvenile diadromous species from undertaking important longitudinal and lateral life-cycle dependant migrations into critical nursery habitats.
Key socio-economic species such as barramundi, sea mullet, mangrove jack, jungle perch, tarpon and long-finned eels are significantly affected. Barriers in the MW region impact freshwater fish communities, affect aquatic ecosystem resilience and reduce the vicarious values the local community places on waterways flowing into the Great Barrier Reef Marine Park.
In many parts of the world remediation of barriers with appropriately designed fishways is one of the most successful management tools utilised by government agencies and natural resource management groups to help reduce the impacts of barriers. However, objectively choosing the ‘right’ barriers to remediate in order to obtain the greatest benefits requires a holistic prioritisation process. The following three stage MW barrier prioritisation process achieves this by investigating the cumulative impacts barriers have on the environment, fishery, economy and local community. The resultant priority ranked list will assist natural resource managers and decision makers in determining where best to allocate limited funding opportunities to ensure the greatest environmental and socio-economic outcomes for the MW region.
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 ontogenetic shifts in habitat use between estuarine and freshwater environments. Remediating barriers and maintaining connectivity between saltwater and freshwater is therefore critical to ensuring freshwater fish community condition and improving overall aquatic ecosystem health. This project aimed to address such issues, through identifying, ranking and remediating fish passage barriers throughout the GB region.
Explicitly, the overall aims of the 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 at several high priority sites in partnership with respective Councils
b. Evaluation monitoring to assess remediation success
c. Field day – South-East Queensland fish passage field trip
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 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.
The GBFBP was also used to guide the remediation of several priority fish barrier sites as part of the overarching project. Fish barrier sites were chosen based on priority ranking and available resources. Five fishways were designed, constructed and monitored by Catchment Solutions (CS) between 2016 and 2017, and delivery of individual fishway projects were undertaken in partnership with each respective Local Government (LG) (Table A). Rock-ramp fishways (RRF) were chosen as the preferred design option at all sites due to their ability to pass weaker swimming juvenile and small bodied species, their natural appearance, pool roughness (creating micro-eddies) and minimal cost outlay when compared to highly engineered, smooth-sided fishways such as vertical-slot fishways. Rock-ramp fishways were constructed on the:
Bremer River (Berrys Weir - ranked 7th),
South Pine River (Leitchs Crossing - ranked 11th),
Hilliards Creek (Hilliards Weir - ranked equal 36th) and
Slacks Creek (Paradise Road overpass - ranked equal 36th). Due to site constraints, a horizontal culvert baffle fishway was constructed in addition to the rock-ramp fishway at Paradise Road on Slacks Creek.
Fishway monitoring was undertaken to evaluate the success of each fishway at facilitating fish passage for the entire fish community. Results showed that all expected juvenile diadromous and small bodied species were able to ascend the fishways. The 2.4 m high, 90 m long, 33 ridge Bremer River partial width rock-ramp fishway recorded the highest numbers and diversity of fish, with over 16,000 individuals recorded in just over four days of monitoring at a catch rate of 4,075 fish per day. The median size of all fish captured was just 34 mm, highlighting the success of the fishway at passing weaker swimming juveniles and small bodied species. Notable captures included the migration of key juvenile diadromous species, such as sea mullet, freshwater mullet and bullrout, which represented catch rates of 316, 266, and 27 individuals per day respectively. The success of each fishway project can be directly attributed to the strong working partnerships developed between CS and each LG to remediate priority fish barriers and deliver significant aquatic connectivity remediation outcomes for the benefit of the environment and local communities.