Fish Learn Stranger Danger
Fri, 26/02/2010 - 9:18am
Stranger danger a tough lesson for young fish
We all learned about stranger danger in school, and scientists have discovered the lesson is just as important for young fish.
Minister for Primary Industries, Fisheries and Rural and Regional Queensland Tim Mulherin said : "As unusual as it sounds researchers have been teaching hatchery reared fingerlings to fear and avoid predators - and it works."
"The research by Queensland Primary Industries and Fisheries is part of a threatened species recovery program.
"One of the key ways to rebuild threatened fish populations is to rear young fish in hatcheries and release them into the wild.
"Unfortunately hatchery reared native fish often suffer the highest mortality rates shortly after being released into their natural habitat.
"The fact they've never been exposed to predators in the hatchery makes them an easy meal.
"Research shows the first few hours are the most perilous with the majority of fish lost during this time, sometimes up to 90 percent.
"That's why this training program being carried out at the Sustainable Fisheries Research Facility at Queensland Primary Industries and Fisheries' (QPIF) Bribie Island Research Centre (BIRC) is so important," he said.
The Minister said the juvenile Murray cod, silver perch and eel-tailed catfish are introduced to predator fish in a protected environment.
"The juvenile fish are placed into one side of a mesh-partitioned tank and on the other side of the tank is a predator fish, a spangled perch, golden perch or a Murray cod," he said.
"Skin extracts from the prey fish containing ‘alarm pheromones' are also placed in the predator side of the tank.
"These chemicals act as a warning to the juveniles and they soon learn to associate the vibrations, smell and sight of the predator with danger.
Mr Mulherin said the laboratory trials have been highly successful.
"Trained fish recognised predators more readily and either maintained their distance from the predator or used cover more effectively, whereas untrained fish became an easy meal," he said.
"Scientists are hoping that training juvenile fish will help rebuild populations in the wild," the Minister said.
Lead scientist Dr Michael Hutchison said the project is co-funded by the Murray-Darling Basin Authority's Native Fish Strategy Program.
"In addition to training the juvenile fish prior to release, scientists are testing the effectiveness of a ‘soft release' into the wild," he said.
"This is where fish are released into their new environment in a predator free cage so they can get their bearings and overcome any transport stress.
"The fish are left in the cage for 90 minutes before it is opened and they can swim out into their new home.
"Field trials are currently underway and will test the difference in survival rates of trained and untrained fish, as well as the effect of the soft release," he said.
Dr Hutchison said if the trials were successful, scientists will be able to restore threatened native fish species in Queensland waterways more quickly and cost-effectively.
Seventy community fish stocking groups throughout Queensland release approximately one million fingerlings each year into more than 100 different water bodies.
Eleven species of native fish and crustaceans are permitted for socking, with restrictions on which species may be stocked into each river catchment.
Popular recreational species in the stocking program include Barramundi, Australian Bass, Golden Perch, Murray Cod, Silver Perch and Sooty Grunter.
For more information contact the Queensland Primary Industries & Fisheries Business Information Centre on 13 25 23 or visit www.dpi.qld.gov.au
We all learned about stranger danger in school, and scientists have discovered the lesson is just as important for young fish.
Minister for Primary Industries, Fisheries and Rural and Regional Queensland Tim Mulherin said : "As unusual as it sounds researchers have been teaching hatchery reared fingerlings to fear and avoid predators - and it works."
"The research by Queensland Primary Industries and Fisheries is part of a threatened species recovery program.
"One of the key ways to rebuild threatened fish populations is to rear young fish in hatcheries and release them into the wild.
"Unfortunately hatchery reared native fish often suffer the highest mortality rates shortly after being released into their natural habitat.
"The fact they've never been exposed to predators in the hatchery makes them an easy meal.
"Research shows the first few hours are the most perilous with the majority of fish lost during this time, sometimes up to 90 percent.
"That's why this training program being carried out at the Sustainable Fisheries Research Facility at Queensland Primary Industries and Fisheries' (QPIF) Bribie Island Research Centre (BIRC) is so important," he said.
The Minister said the juvenile Murray cod, silver perch and eel-tailed catfish are introduced to predator fish in a protected environment.
"The juvenile fish are placed into one side of a mesh-partitioned tank and on the other side of the tank is a predator fish, a spangled perch, golden perch or a Murray cod," he said.
"Skin extracts from the prey fish containing ‘alarm pheromones' are also placed in the predator side of the tank.
"These chemicals act as a warning to the juveniles and they soon learn to associate the vibrations, smell and sight of the predator with danger.
Mr Mulherin said the laboratory trials have been highly successful.
"Trained fish recognised predators more readily and either maintained their distance from the predator or used cover more effectively, whereas untrained fish became an easy meal," he said.
"Scientists are hoping that training juvenile fish will help rebuild populations in the wild," the Minister said.
Lead scientist Dr Michael Hutchison said the project is co-funded by the Murray-Darling Basin Authority's Native Fish Strategy Program.
"In addition to training the juvenile fish prior to release, scientists are testing the effectiveness of a ‘soft release' into the wild," he said.
"This is where fish are released into their new environment in a predator free cage so they can get their bearings and overcome any transport stress.
"The fish are left in the cage for 90 minutes before it is opened and they can swim out into their new home.
"Field trials are currently underway and will test the difference in survival rates of trained and untrained fish, as well as the effect of the soft release," he said.
Dr Hutchison said if the trials were successful, scientists will be able to restore threatened native fish species in Queensland waterways more quickly and cost-effectively.
Seventy community fish stocking groups throughout Queensland release approximately one million fingerlings each year into more than 100 different water bodies.
Eleven species of native fish and crustaceans are permitted for socking, with restrictions on which species may be stocked into each river catchment.
Popular recreational species in the stocking program include Barramundi, Australian Bass, Golden Perch, Murray Cod, Silver Perch and Sooty Grunter.
For more information contact the Queensland Primary Industries & Fisheries Business Information Centre on 13 25 23 or visit www.dpi.qld.gov.au
In other news
