© Copyright The Marron Growers Association of WA 2016
Working Hard for Western Australian Marron Growers

The Marron Growers Bulletin

Free to all members & published twice a year

Full of interesting & informative articles, the Bulletin is an essential magazine for all marron growers. Below we publish a selection of past articles so that you can see the quality & scope of the information the Bulletin contains. If you would like to know more or join the Marron Growers Association of WA, please contact us or download & submit our Membership Application form
Red fin Origins Red fin perch are a little like the rabbit of the water. Like rabbits they were introduced to Australia to provide sport and meat. Like rabbits they are prolific breeders and expert colonizers. They have been introduced to most river systems but also to a large number of independent dams such as old railway and forestry dams. They are adaptable to fresh and brackish water and capable of moving along very minor streams. For example, a keen red fin fisherman working on road construction near my place found large numbers of juveniles in the sludge of late summer in the drain below my farm and established that they came from my place. He then got my permission and caught some buckets full of fish. Many years ago, i have caught them in brackish river pools in the wheat belt east of Narrogin. Red fin perch is a declared pest and it is illegal to return them to our river systems. Like many fresh water fish, they breed most successfully where there are reed beds to support the eggs so numbers may be less prolific in reed free water bodies. The eggs can be transferred through the pumping systems on Marron farms but the juvenile fish will also find their own way along quite minor streams except possibly where there is a complete water fall. So it is likely that if red fin are in your area they will find their way into Marron ponds. impact on Marron farms  In the wild, red fin co-exist with Marron and possibly do not impact too severely on adult Marron numbers, however, they do consume juveniles and therefore are a serious threat to effective Marron production on Marron farms. Native fish are among their preferred foods and one indicator of the presence of red fin in Marron dams may be the disappearance of native fish, such as pygmy perch, that will normally thrive in co-habitation with Marron. On my place, red fin are prolific in the lowest reedy dam and have infiltrated at least four, possibly six other dams on the flood plain. A total of more than two hectares of water has been invaded by red fin. Some of the higher flood plain dams are separated by complete water drops and so far, may be free of red fin. The hillside dams are also believed to be free although one dam could have been infected through the pumping system. invited line fishermen remove some fish but have little impact on the problem. Gill nets have been tried without any success. The worst dams are managed by stocking with larger 1+ Marron so that these dams do produce some Marron but not at the level that could be expected if they could be efficiently stocked with juvenile Marron. it is also reasonable to assume that the red fin may compete for space and some of the foods that Marron eat and this may also restrict Marron production. The dams that are most infested are all spring fed and overflow throughout the year so total draining is not really a desirable option. Chemical treatment with a total poison could be an option but would kill all Marron and risk on-going contamination so has not been considered. it is difficult to be precise because there are so many other variables in a Marron farm but i estimate that with good management of the red fin problem i could initiate production improvements that would be in the order of 500 kg ($15,000.00) annually. Rotenone as a Piscicide About two years ago i read of pest fish control work that was being done near Busselton by Murdoch University. i contacted Dr Stephen Beatty for suggestions to combat my problem with red fin and he suggested that i could explore using rotenone. Rotenone is a piscicide, a fish specific poison that acts on gill fish but does not impact other species. it is derived from the roots of the Derris tree that was traditionally used for catching fish by indigenous people in some tropical countries. it is also widely used in garden dusts and other insecticides. There are numerous articles on the internet regarding the use of Rotenone for pest fish control in various parts of the world for those that want to know more. One such article dealt with a pest fish control attempt by NSW Fisheries in a stream that also contained yabbies. The report indicated that there was an effective fish kill but the yabbies were not impacted. This report, and others, supplied sufficient evidence for me to try rotenone as a resolution to the red fin problem. Rotenone Permits The only permit for use of Rotenone in Australia was issued by the APVMA to the NSW Government and applied to all government departments throughout Australia. Discussion with WA Fisheries indicated that they held stocks of Rotenone and had used it under this permit. The option of having Fisheries contact to treat my farm was discussed but the preferred option was that i seek a private permit. i submitted my application in April 2015 and received a permit in June 2016. The permit is for five years from June 2016 to May 2020. The permit applies only to my farm and various conditions apply with a six month withholding period for Marron sales from the treated water and a three month withholding period for use of water for stock. Both these conditions appear to be excessive by international standards but should not have adverse impacts in my situation. Proposed implementation  I do not have livestock and it is my intention to treat the ponds in about April following a heavy trapping season to remove most size Marron. it will then be possible to restock the dams with juveniles and not do further trapping for market until October. Late summer treatment will enable the level of the lowest dam to be dropped by transfer to replace hill dam evaporation. This will prevent run off from the property. Toxicity also reduces quicker when water temperatures are warmest. i will keep you posted on the results. My expectation is that i will need to do a treatment on some areas each year to cover any missed infestation or reinfestation of the dams. The permit provides for only one treatment of two hectares per twelve month period.

Red Fin Perch

A Marron Farm Pest

By Ron Robertson
If you would like to order a Marron Growers magazine or back issue, please contact us.
The Marron Growers Bulletin has been a regular part of our members lives for over 18 years. Packed full of interesting articles and photographs, it brings together the latest news for all WA marron farmers. We have a range of options for advertising with us, current prices are available from the Association Secretary, you can discuss your business needs & we’ll help identify the best way for you to advertise with us and make the most of your budget. 

White Spot Disease

  White spot disease is a highly contagious viral infection that affects a wide range of crustaceans but does not pose a threat to human health or food safety. The disease has been found in farmed prawn populations in Asia, the Americas and Africa. During the latter half of 2016 a prawn farm on the Logan River in South East Queensland returned positive results for white spot syndrome virus. All prawn farms with stock in the Logan River area have now tested positive for the disease.  All ponds on the seven infected farms are in the gradual process of being drained, dried out and limed as a further decontamination measure. There have also been recent reports of 100 wild giant tiger prawns testing positive for white spot disease in the Logan River and Moreton Bay areas.   Giant tiger prawns are not normally found in that environment, but are of the same variety farmed in the affected area, so it is a reasonable assumption that the prawns came from these farms and it may not indicate that the disease itself is present in the wild population in the river. The source of the outbreak of white spot disease in south-east Queensland has not been determined. There are a number of possible pathways, such as contaminated imported feed, probiotics, contaminated equipment, overseas visitors, poor onfarm biosecurity practices, and brood stock, as well as imported uncooked prawns used as bait. Based on information that the level of risk associated with uncooked imported prawns had become unacceptable, the Director of Biosecurity suspended imports on 6 January 2017.
The department has an extensive product withdrawal program in place to deal with product which was already in the country. The Department of Agriculture and Water Resources has carried out an investigation targeting importers suspected of non-compliance. The investigation has, to date, seen one importer lose their approved arrangement and import permit and the department is in discussion with the CDPP for consideration of possible charges. Action against a number of other importers is being considered and is likely. initially the use of imported uncooked prawns meant for human consumption as bait was thought to be reasonably low. Departmental investigators surveying recreational fishers in the Logan River area during the holiday period just passed, found fishers using imported prawns meant for human consumption as bait. Testing indicated that some of the prawns were positive for white spot disease. Around the same time, the department collected samples of imported raw prawns available for sale in the area. The results showed a significant number of prawns were positive for white spot disease. To reduce the risk associated with product already in the country at the time of the suspension, the department is working closely with major retailers to withdraw infected product from the market. WA Fisheries and Marine Officers are working at WA’s borders with staff from the Department of Agriculture and Food to inspect consignments and clear those that meet the import requirements. Based on current information and good progress, the authorities remain of the view that the disease can be eradicated. it should be noted that while a full range of sources has been investigated, at the time of publication there has been no link between the outbreak and imported feed products or probiotics. For a complete overview and updates on this incident, keep an eye on the following links. http://www.fish.wa.gov.au/Sustainability-andEnvironment/Aquatic- Biosecurity/Pages/Biosecurityincidents.aspx  https://www.daf.qld.gov.au/animal-industries/ animal-health-and-diseases/a- z-list/white-spotdisease/information-for-prawn-farmers 

In this edition of the Marron Growers Bulletin

President’s Message Windarra Ponds Redfin Perch Marron Growers Field Day and AGM Update on Curtin University Marron Research Project White Spot Disease Membership Application Form
© Copyright The Marron Growers Association of WA 2016
Working Hard for Western Australian Marron Growers

The Marron

Growers Bulletin

Free to all members & published twice a year

Full of interesting & informative articles, the Bulletin is an essential magazine for all marron growers. Below we publish a selection of past articles so that you can see the quality & scope of the information the Bulletin contains. If you would like to know more or join the Marron Growers Association of WA, please contact us or download & submit our Membership Application form
Red fin Origins Red fin perch are a little like the rabbit of the water. Like rabbits they were introduced to Australia to provide sport and meat. Like rabbits they are prolific breeders and expert colonizers. They have been introduced to most river systems but also to a large number of independent dams such as old railway and forestry dams. They are adaptable to fresh and brackish water and capable of moving along very minor streams. For example, a keen red fin fisherman working on road construction near my place found large numbers of juveniles in the sludge of late summer in the drain below my farm and established that they came from my place. He then got my permission and caught some buckets full of fish. Many years ago, i have caught them in brackish river pools in the wheat belt east of Narrogin. Red fin perch is a declared pest and it is illegal to return them to our river systems. Like many fresh water fish, they breed most successfully where there are reed beds to support the eggs so numbers may be less prolific in reed free water bodies. The eggs can be transferred through the pumping systems on Marron farms but the juvenile fish will also find their own way along quite minor streams except possibly where there is a complete water fall. So it is likely that if red fin are in your area they will find their way into Marron ponds. impact on Marron farms  In the wild, red fin co-exist with Marron and possibly do not impact too severely on adult Marron numbers, however, they do consume juveniles and therefore are a serious threat to effective Marron production on Marron farms. Native fish are among their preferred foods and one indicator of the presence of red fin in Marron dams may be the disappearance of native fish, such as pygmy perch, that will normally thrive in co-habitation with Marron. On my place, red fin are prolific in the lowest reedy dam and have infiltrated at least four, possibly six other dams on the flood plain. A total of more than two hectares of water has been invaded by red fin. Some of the higher flood plain dams are separated by complete water drops and so far, may be free of red fin. The hillside dams are also believed to be free although one dam could have been infected through the pumping system. invited line fishermen remove some fish but have little impact on the problem. Gill nets have been tried without any success. The worst dams are managed by stocking with larger 1+ Marron so that these dams do produce some Marron but not at the level that could be expected if they could be efficiently stocked with juvenile Marron. it is also reasonable to assume that the red fin may compete for space and some of the foods that Marron eat and this may also restrict Marron production. The dams that are most infested are all spring fed and overflow throughout the year so total draining is not really a desirable option. Chemical treatment with a total poison could be an option but would kill all Marron and risk on-going contamination so has not been considered. it is difficult to be precise because there are so many other variables in a Marron farm but i estimate that with good management of the red fin problem i could initiate production improvements that would be in the order of 500 kg ($15,000.00) annually. Rotenone as a Piscicide About two years ago i read of pest fish control work that was being done near Busselton by Murdoch University. i contacted Dr Stephen Beatty for suggestions to combat my problem with red fin and he suggested that i could explore using rotenone. Rotenone is a piscicide, a fish specific poison that acts on gill fish but does not impact other species. it is derived from the roots of the Derris tree that was traditionally used for catching fish by indigenous people in some tropical countries. it is also widely used in garden dusts and other insecticides. There are numerous articles on the internet regarding the use of Rotenone for pest fish control in various parts of the world for those that want to know more. One such article dealt with a pest fish control attempt by NSW Fisheries in a stream that also contained yabbies. The report indicated that there was an effective fish kill but the yabbies were not impacted. This report, and others, supplied sufficient evidence for me to try rotenone as a resolution to the red fin problem. Rotenone Permits The only permit for use of Rotenone in Australia was issued by the APVMA to the NSW Government and applied to all government departments throughout Australia. Discussion with WA Fisheries indicated that they held stocks of Rotenone and had used it under this permit. The option of having Fisheries contact to treat my farm was discussed but the preferred option was that i seek a private permit. i submitted my application in April 2015 and received a permit in June 2016. The permit is for five years from June 2016 to May 2020. The permit applies only to my farm and various conditions apply with a six month withholding period for Marron sales from the treated water and a three month withholding period for use of water for stock. Both these conditions appear to be excessive by international standards but should not have adverse impacts in my situation. Proposed implementation  I do not have livestock and it is my intention to treat the ponds in about April following a heavy trapping season to remove most size Marron. it will then be possible to restock the dams with juveniles and not do further trapping for market until October. Late summer treatment will enable the level of the lowest dam to be dropped by transfer to replace hill dam evaporation. This will prevent run off from the property. Toxicity also reduces quicker when water temperatures are warmest. i will keep you posted on the results. My expectation is that i will need to do a treatment on some areas each year to cover any missed infestation or reinfestation of the dams. The permit provides for only one treatment of two hectares per twelve month period.

Red Fin Perch

A Marron Farm Pest

By Ron Robertson
If you would like to order a Marron Growers magazine or back issue, please contact us.

White Spot Disease

White spot disease is a highly contagious viral infection that affects a wide range of crustaceans but does not pose a threat to human health or food safety. The disease has been found in farmed prawn populations in Asia, the Americas and Africa. During the latter half of 2016 a prawn farm on the Logan River in South East Queensland returned positive results for white spot syndrome virus. All prawn farms with stock in the Logan River area have now tested positive for the disease.  All ponds on the seven infected farms are in the gradual process of being drained, dried out and limed as a further decontamination measure. There have also been recent reports of 100 wild giant tiger prawns testing positive for white spot disease in the Logan River and Moreton Bay areas.   Giant tiger prawns are not normally found in that environment, but are of the same variety farmed in the affected area, so it is a reasonable assumption that the prawns came from these farms and it may not indicate that the disease itself is present in the wild population in the river. The source of the outbreak of white spot disease in south-east Queensland has not been determined. There are a number of possible pathways, such as contaminated imported feed, probiotics, contaminated equipment, overseas visitors, poor onfarm biosecurity practices, and brood stock, as well as imported uncooked prawns used as bait. Based on information that the level of risk associated with uncooked imported prawns had become unacceptable, the Director of Biosecurity suspended imports on 6 January 2017. The department has an extensive product withdrawal program in place to deal with product which was already in the country. The Department of Agriculture and Water Resources has carried out an investigation targeting importers suspected of non-compliance. The investigation has, to date, seen one importer lose their approved arrangement and import permit and the department is in discussion with the CDPP for consideration of possible charges. Action against a number of other importers is being considered and is likely. initially the use of imported uncooked prawns meant for human consumption as bait was thought to be reasonably low. Departmental investigators surveying recreational fishers in the Logan River area during the holiday period just passed, found fishers using imported prawns meant for human consumption as bait. Testing indicated that some of the prawns were positive for white spot disease. Around the same time, the department collected samples of imported raw prawns available for sale in the area. The results showed a significant number of prawns were positive for white spot disease. To reduce the risk associated with product already in the country at the time of the suspension, the department is working closely with major retailers to withdraw infected product from the market. WA Fisheries and Marine Officers are working at WA’s borders with staff from the Department of Agriculture and Food to inspect consignments and clear those that meet the import requirements. Based on current information and good progress, the authorities remain of the view that the disease can be eradicated. it should be noted that while a full range of sources has been investigated, at the time of publication there has been no link between the outbreak and imported feed products or probiotics. For a complete overview and updates on this incident, keep an eye on the following links. http://www.fish.wa.gov.au/Sustainability- andEnvironment/Aquatic- Biosecurity/Pages/Biosecurityincidents.aspx  https://www.daf.qld.gov.au/animal-industries/ animal- health-and-diseases/a-z-list/white-spotdisease/information- for-prawn-farmers