MOST DAMAGING THREATS TO OUR WATERWAYS
VERY NEGATIVE EFFECT OF DAMS AND WEIRS
This is a subject many of the "Blame Carp for everything" promoters don't want to talk about or have too much focus on. It is most probably the single biggest contributor to low native fish numbers and high carp biomass. They prevent natives from doing on their natural migrations, create COLD WATER / THERMAL POLLUTION which kills millions of young native fishes and prevent adults from breeding, hold back silt sediments and pollutants , contribute towards Algal blooms. Recreational fisherman who want to know more about why their preferred target species are not around will get many answers by reading through these articles. Carp may be the most abundant fish but they are not the reason why you are not catching more native fish.
"In the Murray-Darling Basin alone there are over 40,000 known barriers to fish movement. Many of these are what they call ‘undershot weirs’, which release water underneath steel gates as opposed to over a fixed crest. These weir designs have been shown to be particularly harmful to Golden Perch and Murray Cod: with a recent study estimating that as many as 95% of Golden Perch larvae and 52% of Murray Cod larvae are killed as they move downstream through these structures.
There are also irrigation pumps and canals along many of our rivers, and research undertaken by NSW DPI staff has shown that native fish are being sucked into them in very large numbers, and are either killed or transported into artificial water bodies used for irrigation, unable to return to the river. This is a particular concern for young fish (eggs, larvae and juveniles), and particularly species such as Murray Cod, Golden Perch, Silver Perch and Trout Cod, which drift downstream as larvae after hatching, making them particularly vulnerable. Their drifting phase also coincides with peak irrigation periods (November and December).
Source: http://www.finterest.com.au/natives-and-introduced/native-fish-natives-and-introduced/going-with-the-flow/
COLD WATER POLLUTION:
This does not only prevent adult fish from breeding but also kill millions of young native fish every year. Many of these are predatory native fish who prey on carp. A couple million more of these natives would therefore not only be great for recreational fishing but will play a significant role in controlling the biomass of non-native species like carp, (Create the right environment and nature will look after itself)
“Some species of native fish can disappear from large sections of the river.
Some examples of the effects of cold water releases on native fish in NSW include:
Sources:
http://www.water.nsw.gov.au/water-management/water-quality/temperature
http://www.dpi.nsw.gov.au/fishing/habitat/threats/cold-water-pollution
http://www.weeklytimesnow.com.au/news/national/coldwater-pollution-driveing-native-fish-out-of-murray-darling-basin/news-story/df93c8624d12ca129c34ebc7a77fca15
NEGATIVE EFFECT ON BIRDLIFE
Water birds in the Murray-Darling Basin have fallen 70 per cent in the past three decades, and scientists believe damming is behind their decline.
Source: http://ab.co/2rV1SAy
DAMS AND WEIRS PREVENT NATURAL MIGRATION FOR NATIVE FISH SPECIES
Australian fish are dependent on migration to breed as adults, find habitat and seek refuge during droughts.
Barriers to migration have been identified as a major contributor to the decline of native fish species within the Murray Darling Basin. Recognition within the Murray-Darling Basin Authority’s (MDBA) Native Fish Strategy of their impacts on river health and their listing as a key threatening process in state and Commonwealth threatened species legislation is evidence of their impact on aquatic biodiversity.
The MDBA have made significant investment in improving fish passage along the Murray River and associated anabranches through the Lake Hume to the Sea program and the Living Murray Initiative, although this investment has not been matched in the Northern Murray-Darling Basin. At present, the movement of fish within and between river systems north of Menindee Lakes remains significantly restricted by dams and weirs without adequate fish passage.
http://www.dpi.nsw.gov.au/fishing/habitat/publications/pubs/fishway-options-for-weirs-in-the-northern-murray-darling-basin
https://www.mdba.gov.au/sites/default/files/archived/mdbc-NFS-reports/2199_brochure_river_murray_barrages_and_fishways.pdf
DESNAGGING – REMOVAL OF CRUCIAL HABITAT:
What are snags?
Snags are trees, branches and root masses that are found in our rivers. Also known as large woody debris, snags result from trees on the river bank either falling in or dropping
their branches. This can occur because of flooding, bank erosion, wind or limb shedding and is a natural process.
Why are snags important?
Snags provide extremely important habitat for aquatic life, particularly native fish. There are around 45 native fish species in the Murray–Darling Basin. Many of these species,
such as Golden perch, River blackfish, Murray cod, and the critically endangered Trout cod, rely on snags for a number of reasons.
Snags provide fish with:
• sites to attach adhesive eggs during breeding;
• sites to rest from fast river flows;
• shelter from predators;
• landmarks to define territories and aid navigation;
• ambush sites.
Some native fish even have preferences for certain types of snags and their location within the river. Trout cod for example have been shown to use snags closer to the
middle of a river, whereas Murray cod use snags closer to the river bank.
Macroinvertebrates, an important food source for many native fish, use snags not only for shelter, but also as food, grazing on the wood itself and the microbes and algae that grow on
it. Snags are also important habitat for other terrestrial and aquatic animals, such as birds and amphibians.
Snags play an important role in shaping our rivers, creating variability in depth and flow that in turn leads to a greater range of habitat for fish and other aquatic life. As a significant source of carbon, snags also contribute to the chemical composition of the water.
Where have all the snags gone?
Some rivers of the Murray–Darling Basin still have good numbers of snags, an asset that should be managed to ensure their protection. However, millions of snags have been deliberately removed in the past in large-scale desnagging operations. These largely came about because of several misconceptions. Among these was the belief that snags cause erosion of river banks. While in certain instances they may contribute to small-scale and short-term erosion, in many cases the presence of natural loads of snags may reduce erosion by protecting the river banks. Many also thought that snags increased the incidence
of flooding by reducing the capacity of water that the river channel could hold, a view we now know to be largely incorrect.
The effects of snag removal are long-lasting. In fact, the removal of snags, or desnagging, is acknowledged as one of the primary threats to native fish in the Murray–Darling Basin’s Native Fish Strategy – a long-term plan to rehabilitate the Basin’s native fish populations. Furthermore, snags are now protected in some States by legislation, with heavy fines for illegal removal.
Source:
https://www.mdba.gov.au/sites/default/files/pubs/Snags_Resnagging-FS.pdf
ALGAL BLOOMS:
Carp is also blamed for this and many are fooled into thinking that carp somehow is the main cause. The following articles / Government documents discuss the effect and causes of algal blooms, Carp is not mentioned once. We're not saying carp have a zero affect but simply point out that things needs to be viewed in perspective and that other factors have a far bigger effect. Please read the full articles to have a better understanding of who and what the main causes are.
"A combination of environmental conditions is associated with blooms - a stable water column, sunlight and nutrients - but no single factor can ever be implicated as the sole perpetrator. ”People often have this idea that algal blooms are nutrient-driven events, but it's not the case," says Professor Gary Jones, chief executive of water management company, eWater CRC, and former algal expert for CSIRO. "It's far more complex than that."
This complexity is why, when it comes to mitigating blue-green algal blooms, "there aren't too many silver bullets," says Gary.
Long-term solutions focus on maintaining vegetation to minimise erosion, and therefore nutrient run-off, within a catchment. But of all the short-term solutions, which include methods like stripping phosphorus out of the water, Gary says that only 'thermal destratification' - artificially mixing water to prevent cyanobacteria from collecting in the warm upper layers - comes close to being successful."
Source: http://www.australiangeographic.com.au/topics/science-environment/2012/04/algal-blooms-a-colourful-danger/
"Nutrients are either naturally present in sediments or are washed into water systems. In particular, phosphorus may be stored in significant amounts in sediments and released by normal bacterial activity. External sources of nitrogen and phosphorus are agricultural fertilisers, household products, sewage effluent and stormwater runoff, all of which can enter receiving waters either directly or during rainfall events. The availability of varying levels of nitrogen and phosphorus can affect which species of blue-green algae dominate and form blooms. Blooms can form in response to increased temperatures and phosphorus levels even if nitrogen in water remains low, as some blue-green algae species can obtain nitrogen from the atmosphere."
"The most effective method of preventing blue-green algal blooms is to minimise the nutrient load entering waterways through actions such as planting or maintaining riparian vegetation, conserving soil, and implementing appropriate treatment and disposal of stormwater, agricultural, industrial and sewage effluent. Flow manipulation can also be used to prevent the build-up of blue-green algae or to disperse blooms."
Source: http://www.agriculture.gov.au/water/quality/blue-green-algae
"The 2007, 2009 and 2010 algal blooms on the Murray River all happened during the Millennium Drought, and hence were probably ascribed to an aberration in the weather. In reality, the situation may have more to do with how we manage water in Australia – particularly during periods of scarcity..."
Source: http://theconversation.com/are-toxic-algal-blooms-the-new-normal-for-australias-major-rivers-59526
OTHER INVASIVE FISH
The following are some of the introduced species: Brown trout, Rainbow trout, Tilapia, Redfin, Goldfish and Mosquito fish.
BROWN AND RAINBOW TROUT
I must start this section by saying that as a sport fisherman I do support fishing for trout as a sport and healthy way to spend time in nature, much like Carp fishing. Trout however has also had a negative impact on native species and is therefor also listed on this page. It is interesting to see how Local Governments and Recreational fishing bodies strongly support and pay for the release of millions of these Internationally listed Invasive and Non-native feral fish for its social and economic value but can't see the benefits of carp which in my opinion, based on there wide distribution and international reputation as sportfish, have far greater potential to make a significantly bigger contribution to Australia. Interesting to see how the above groups and Trout anglers are staunch supporters of the Koi Herpes Virus aimed at removing an Invasive / Non-Native species (same as Rainbow and Brown Trout).
Brown and Rainbow trout are two of the eight fish species listed on the International Union for Conservation of Nature’s list of 100 most invasive species.
Source: https://portals.iucn.org/library/sites/library/files/documents/2000-126.pdf
Article - Rabbits of the river: Trout are not native to Australia "The surprising thing is that trout have evaded the pest label, and despite abundant evidence that they are causing the extinction of native fauna, their continued existence in Australian rivers is supported by government agencies that release millions of trout fry every year".
Source: http://theconversation.com/rabbits-of-the-river-trout-are-not-native-to-australia-14115
The substantial contribution of C. cainii (Marron), to the diet of wild O. mykiss (Trout) suggests that, at least in habitat limited water bodies, it is likely to have a considerable predatory impact on C. cainii (Marron) populations and may compromise some elements of this iconic recreational fishery.
Source: http://www.tandfonline.com/doi/abs/10.1080/00288330709509908
Rainbow Trout and Brown trout are listed as FERAL FISH SPECIES yet heavily stocked annually into Western Australia's south-west rivers and dams.
Source: http://www.freshwaterfishgroup.com/feral-fishes.php
REDFIN PERCH
Redfin are voracious predators which consume a wide variety of fish and invertebrates, including small native species such as Pygmy perch, Rainbowfish and Carp gudgeon, and the eggs and fry of larger fish such as Silver perch, Golden perch, Murray cod and introduced trout.
http://www.dpi.nsw.gov.au/fishing/pests-diseases/freshwater-pests/species/redfin-perch
EASTERN GAMBUSIA
Eastern gambusia (Gambusia holbrooki - also known as Plague minnow, Gambusia and Mosquito fish) are native to south-eastern USA. Eastern gambusia are known to compete with native species for food and resources. They can behave aggressively towards other species by chasing and fin nipping, which can lead to secondary bacterial or fungal infections and potentially death of other fish. They are also known to prey upon the eggs and juveniles of other fish species.
http://www.dpi.nsw.gov.au/fishing/pests-diseases/freshwater-pests/species/gambusia
TILAPIA
Impacts tilapia have on native fish and habitats include:
•competition with native species for food and space
•predation upon the eggs and young of native species
•aggressive behaviour of tilapia can lead to poor condition and higher infection and mortality rates for native species
•nest building by male tilapia may also damage aquatic habitats through damage to aquatic vegetation and increased turbidity.
http://www.dpi.nsw.gov.au/fishing/pests-diseases/freshwater-pests/species/tilapia
HISTORIC OVERFISHING:
Historic Commercial and Recreational overfishing played a significant role in the demise and near collapse of certain native species. Interesting to think that Commercial and Recreational anglers will now play a very significant role in the success of C.A.R.P.
http://theconversation.com/australian-endangered-species-murray-cod-12555
GENERAL READING:
The following article discuss a number of the threats listed above.
http://theconversation.com/we-need-more-than-just-extra-water-to-save-the-murray-darling-basin-80188
VERY NEGATIVE EFFECT OF DAMS AND WEIRS
This is a subject many of the "Blame Carp for everything" promoters don't want to talk about or have too much focus on. It is most probably the single biggest contributor to low native fish numbers and high carp biomass. They prevent natives from doing on their natural migrations, create COLD WATER / THERMAL POLLUTION which kills millions of young native fishes and prevent adults from breeding, hold back silt sediments and pollutants , contribute towards Algal blooms. Recreational fisherman who want to know more about why their preferred target species are not around will get many answers by reading through these articles. Carp may be the most abundant fish but they are not the reason why you are not catching more native fish.
"In the Murray-Darling Basin alone there are over 40,000 known barriers to fish movement. Many of these are what they call ‘undershot weirs’, which release water underneath steel gates as opposed to over a fixed crest. These weir designs have been shown to be particularly harmful to Golden Perch and Murray Cod: with a recent study estimating that as many as 95% of Golden Perch larvae and 52% of Murray Cod larvae are killed as they move downstream through these structures.
There are also irrigation pumps and canals along many of our rivers, and research undertaken by NSW DPI staff has shown that native fish are being sucked into them in very large numbers, and are either killed or transported into artificial water bodies used for irrigation, unable to return to the river. This is a particular concern for young fish (eggs, larvae and juveniles), and particularly species such as Murray Cod, Golden Perch, Silver Perch and Trout Cod, which drift downstream as larvae after hatching, making them particularly vulnerable. Their drifting phase also coincides with peak irrigation periods (November and December).
Source: http://www.finterest.com.au/natives-and-introduced/native-fish-natives-and-introduced/going-with-the-flow/
COLD WATER POLLUTION:
This does not only prevent adult fish from breeding but also kill millions of young native fish every year. Many of these are predatory native fish who prey on carp. A couple million more of these natives would therefore not only be great for recreational fishing but will play a significant role in controlling the biomass of non-native species like carp, (Create the right environment and nature will look after itself)
“Some species of native fish can disappear from large sections of the river.
Some examples of the effects of cold water releases on native fish in NSW include:
- elimination of trout cod, Macquarie perch and freshwater blackfish from large sections of the Murrumbidgee River downstream from Blowering Dam
- loss of trout cod, Macquarie perch and freshwater catfish from the Murray River downstream from Hume Dam
- loss of silver perch, Murray cod, rainbowfish and bony herring from the Macquarie River for up to 300 km downstream from Burrendong Dam
- suppressed breeding of native fish, particularly silver perch, in the Namoi River as far as 100 km downstream of Keepit Dam
- 50 per cent of juvenile silver perch killed after only 30 days of exposure to cold water in a study conducted by NSW Fisheries.
Sources:
http://www.water.nsw.gov.au/water-management/water-quality/temperature
http://www.dpi.nsw.gov.au/fishing/habitat/threats/cold-water-pollution
http://www.weeklytimesnow.com.au/news/national/coldwater-pollution-driveing-native-fish-out-of-murray-darling-basin/news-story/df93c8624d12ca129c34ebc7a77fca15
NEGATIVE EFFECT ON BIRDLIFE
Water birds in the Murray-Darling Basin have fallen 70 per cent in the past three decades, and scientists believe damming is behind their decline.
Source: http://ab.co/2rV1SAy
DAMS AND WEIRS PREVENT NATURAL MIGRATION FOR NATIVE FISH SPECIES
Australian fish are dependent on migration to breed as adults, find habitat and seek refuge during droughts.
Barriers to migration have been identified as a major contributor to the decline of native fish species within the Murray Darling Basin. Recognition within the Murray-Darling Basin Authority’s (MDBA) Native Fish Strategy of their impacts on river health and their listing as a key threatening process in state and Commonwealth threatened species legislation is evidence of their impact on aquatic biodiversity.
The MDBA have made significant investment in improving fish passage along the Murray River and associated anabranches through the Lake Hume to the Sea program and the Living Murray Initiative, although this investment has not been matched in the Northern Murray-Darling Basin. At present, the movement of fish within and between river systems north of Menindee Lakes remains significantly restricted by dams and weirs without adequate fish passage.
http://www.dpi.nsw.gov.au/fishing/habitat/publications/pubs/fishway-options-for-weirs-in-the-northern-murray-darling-basin
https://www.mdba.gov.au/sites/default/files/archived/mdbc-NFS-reports/2199_brochure_river_murray_barrages_and_fishways.pdf
DESNAGGING – REMOVAL OF CRUCIAL HABITAT:
What are snags?
Snags are trees, branches and root masses that are found in our rivers. Also known as large woody debris, snags result from trees on the river bank either falling in or dropping
their branches. This can occur because of flooding, bank erosion, wind or limb shedding and is a natural process.
Why are snags important?
Snags provide extremely important habitat for aquatic life, particularly native fish. There are around 45 native fish species in the Murray–Darling Basin. Many of these species,
such as Golden perch, River blackfish, Murray cod, and the critically endangered Trout cod, rely on snags for a number of reasons.
Snags provide fish with:
• sites to attach adhesive eggs during breeding;
• sites to rest from fast river flows;
• shelter from predators;
• landmarks to define territories and aid navigation;
• ambush sites.
Some native fish even have preferences for certain types of snags and their location within the river. Trout cod for example have been shown to use snags closer to the
middle of a river, whereas Murray cod use snags closer to the river bank.
Macroinvertebrates, an important food source for many native fish, use snags not only for shelter, but also as food, grazing on the wood itself and the microbes and algae that grow on
it. Snags are also important habitat for other terrestrial and aquatic animals, such as birds and amphibians.
Snags play an important role in shaping our rivers, creating variability in depth and flow that in turn leads to a greater range of habitat for fish and other aquatic life. As a significant source of carbon, snags also contribute to the chemical composition of the water.
Where have all the snags gone?
Some rivers of the Murray–Darling Basin still have good numbers of snags, an asset that should be managed to ensure their protection. However, millions of snags have been deliberately removed in the past in large-scale desnagging operations. These largely came about because of several misconceptions. Among these was the belief that snags cause erosion of river banks. While in certain instances they may contribute to small-scale and short-term erosion, in many cases the presence of natural loads of snags may reduce erosion by protecting the river banks. Many also thought that snags increased the incidence
of flooding by reducing the capacity of water that the river channel could hold, a view we now know to be largely incorrect.
The effects of snag removal are long-lasting. In fact, the removal of snags, or desnagging, is acknowledged as one of the primary threats to native fish in the Murray–Darling Basin’s Native Fish Strategy – a long-term plan to rehabilitate the Basin’s native fish populations. Furthermore, snags are now protected in some States by legislation, with heavy fines for illegal removal.
Source:
https://www.mdba.gov.au/sites/default/files/pubs/Snags_Resnagging-FS.pdf
ALGAL BLOOMS:
Carp is also blamed for this and many are fooled into thinking that carp somehow is the main cause. The following articles / Government documents discuss the effect and causes of algal blooms, Carp is not mentioned once. We're not saying carp have a zero affect but simply point out that things needs to be viewed in perspective and that other factors have a far bigger effect. Please read the full articles to have a better understanding of who and what the main causes are.
"A combination of environmental conditions is associated with blooms - a stable water column, sunlight and nutrients - but no single factor can ever be implicated as the sole perpetrator. ”People often have this idea that algal blooms are nutrient-driven events, but it's not the case," says Professor Gary Jones, chief executive of water management company, eWater CRC, and former algal expert for CSIRO. "It's far more complex than that."
This complexity is why, when it comes to mitigating blue-green algal blooms, "there aren't too many silver bullets," says Gary.
Long-term solutions focus on maintaining vegetation to minimise erosion, and therefore nutrient run-off, within a catchment. But of all the short-term solutions, which include methods like stripping phosphorus out of the water, Gary says that only 'thermal destratification' - artificially mixing water to prevent cyanobacteria from collecting in the warm upper layers - comes close to being successful."
Source: http://www.australiangeographic.com.au/topics/science-environment/2012/04/algal-blooms-a-colourful-danger/
"Nutrients are either naturally present in sediments or are washed into water systems. In particular, phosphorus may be stored in significant amounts in sediments and released by normal bacterial activity. External sources of nitrogen and phosphorus are agricultural fertilisers, household products, sewage effluent and stormwater runoff, all of which can enter receiving waters either directly or during rainfall events. The availability of varying levels of nitrogen and phosphorus can affect which species of blue-green algae dominate and form blooms. Blooms can form in response to increased temperatures and phosphorus levels even if nitrogen in water remains low, as some blue-green algae species can obtain nitrogen from the atmosphere."
"The most effective method of preventing blue-green algal blooms is to minimise the nutrient load entering waterways through actions such as planting or maintaining riparian vegetation, conserving soil, and implementing appropriate treatment and disposal of stormwater, agricultural, industrial and sewage effluent. Flow manipulation can also be used to prevent the build-up of blue-green algae or to disperse blooms."
Source: http://www.agriculture.gov.au/water/quality/blue-green-algae
"The 2007, 2009 and 2010 algal blooms on the Murray River all happened during the Millennium Drought, and hence were probably ascribed to an aberration in the weather. In reality, the situation may have more to do with how we manage water in Australia – particularly during periods of scarcity..."
Source: http://theconversation.com/are-toxic-algal-blooms-the-new-normal-for-australias-major-rivers-59526
OTHER INVASIVE FISH
The following are some of the introduced species: Brown trout, Rainbow trout, Tilapia, Redfin, Goldfish and Mosquito fish.
BROWN AND RAINBOW TROUT
I must start this section by saying that as a sport fisherman I do support fishing for trout as a sport and healthy way to spend time in nature, much like Carp fishing. Trout however has also had a negative impact on native species and is therefor also listed on this page. It is interesting to see how Local Governments and Recreational fishing bodies strongly support and pay for the release of millions of these Internationally listed Invasive and Non-native feral fish for its social and economic value but can't see the benefits of carp which in my opinion, based on there wide distribution and international reputation as sportfish, have far greater potential to make a significantly bigger contribution to Australia. Interesting to see how the above groups and Trout anglers are staunch supporters of the Koi Herpes Virus aimed at removing an Invasive / Non-Native species (same as Rainbow and Brown Trout).
Brown and Rainbow trout are two of the eight fish species listed on the International Union for Conservation of Nature’s list of 100 most invasive species.
Source: https://portals.iucn.org/library/sites/library/files/documents/2000-126.pdf
Article - Rabbits of the river: Trout are not native to Australia "The surprising thing is that trout have evaded the pest label, and despite abundant evidence that they are causing the extinction of native fauna, their continued existence in Australian rivers is supported by government agencies that release millions of trout fry every year".
Source: http://theconversation.com/rabbits-of-the-river-trout-are-not-native-to-australia-14115
The substantial contribution of C. cainii (Marron), to the diet of wild O. mykiss (Trout) suggests that, at least in habitat limited water bodies, it is likely to have a considerable predatory impact on C. cainii (Marron) populations and may compromise some elements of this iconic recreational fishery.
Source: http://www.tandfonline.com/doi/abs/10.1080/00288330709509908
Rainbow Trout and Brown trout are listed as FERAL FISH SPECIES yet heavily stocked annually into Western Australia's south-west rivers and dams.
Source: http://www.freshwaterfishgroup.com/feral-fishes.php
REDFIN PERCH
Redfin are voracious predators which consume a wide variety of fish and invertebrates, including small native species such as Pygmy perch, Rainbowfish and Carp gudgeon, and the eggs and fry of larger fish such as Silver perch, Golden perch, Murray cod and introduced trout.
http://www.dpi.nsw.gov.au/fishing/pests-diseases/freshwater-pests/species/redfin-perch
EASTERN GAMBUSIA
Eastern gambusia (Gambusia holbrooki - also known as Plague minnow, Gambusia and Mosquito fish) are native to south-eastern USA. Eastern gambusia are known to compete with native species for food and resources. They can behave aggressively towards other species by chasing and fin nipping, which can lead to secondary bacterial or fungal infections and potentially death of other fish. They are also known to prey upon the eggs and juveniles of other fish species.
http://www.dpi.nsw.gov.au/fishing/pests-diseases/freshwater-pests/species/gambusia
TILAPIA
Impacts tilapia have on native fish and habitats include:
•competition with native species for food and space
•predation upon the eggs and young of native species
•aggressive behaviour of tilapia can lead to poor condition and higher infection and mortality rates for native species
•nest building by male tilapia may also damage aquatic habitats through damage to aquatic vegetation and increased turbidity.
http://www.dpi.nsw.gov.au/fishing/pests-diseases/freshwater-pests/species/tilapia
HISTORIC OVERFISHING:
Historic Commercial and Recreational overfishing played a significant role in the demise and near collapse of certain native species. Interesting to think that Commercial and Recreational anglers will now play a very significant role in the success of C.A.R.P.
http://theconversation.com/australian-endangered-species-murray-cod-12555
GENERAL READING:
The following article discuss a number of the threats listed above.
http://theconversation.com/we-need-more-than-just-extra-water-to-save-the-murray-darling-basin-80188