Murray–Darling Basin Authority Native Fish Strategy Strategies to improve post release survival of hatchery-reared threatened fish species Michael Hutchison, Danielle Stewart, Keith Chilcott, Adam Butcher, Angela Henderson
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- Species trained Treatment Evaluation type Number of replicates
| Figure 3: Tank set up used to test response of freshwater catfish and Murray cod to predatory fish. Note semi-permeable screen to contain the predator and use of open water and cover areas in the predator, near centre and far cells. The experiment pictured shows a control group of catfish after introduction of a predator (Murray cod) to the tank. (Freeze frame from video monitor).
Table 1: Evaluation experiments for fingerlings
b. Response to simulated bird The response of fingerlings of silver perch, Murray cod and freshwater catfish to a simulated bird predator was tested using a similar tank set up to that shown in Figure 5. The only difference being that the predator screening was removed. As for the predatory fish experiments, fingerlings were introduced to the tank and allowed to settle for 30 minutes. Recording then commenced and after 15 minutes a simulated bird predator was introduced for one minute, and then withdrawn. It was introduced again after four minutes for a further minute and withdrawn again. After another four minutes the simulated bird predator was introduced for a final minute. Filming continued for 15 minutes after the first introduction of the simulated predator. The simulated predator was made from plywood and cut into the shape of a cormorant. Underneath it was painted to mimic cormorant markings. A bunch of cormorant feathers was attached by fishing line to the base of the wooden bird (Figure 4). When simulating presence of a bird predator the wooden silhouette was moved back and forth over the predator cells of the test tank. The silhouette was fixed to the end of a PVC pole and was manoeuvred over the tank by a person hidden behind a black plastic screen. The cormorant feathers were permitted to dangle into the water to introduce cormorant odour. Predatory bird response evaluation experiments tested groups of eight fingerlings, with 12 replicates for each treatment. However, the numbers of replicates for catfish were reduced to 8 from twelve (refer to Table 1), as there was a shortage of suitable catfish fingerlings. At the conclusion of all experiments videos of the simulated bird attacks were viewed and the position of fingerlings in each test tank was recorded every 15 seconds, for 15 minutes before and after introduction of the simulated predator. Movements of cod and catfish were also recorded for each 15 second segment. 
Figure 4: Cormorant silhouette. Note the feathers attached by fishing line to provide cormorant odour. (Photo M. Hutchison) Directory: sites -> default -> files -> pubs files -> Northern England’s set-jetting locations files -> Nstructions for Acquiring Excess Equipment online, through the 1033 Program files -> Occupational health and safety files -> The Black Panther Party’s Ten Point Program files -> International programs roel profile files -> Fermi Questions a guide for Teachers, Students, and Event Supervisors Lloyd Abrams, Ph. D. DuPont Company, cr&D/ccas experimental Station Wilmington, de 19880 files -> Personal Information Name: Maha Al-Ammari Nationality: Saudi Relationship Status pubs -> Aboriginal Partnerships Action Plan Download 3.02 Mb. Share with your friends:
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