Where do you think most lost fish end up?
You can't find them dead, you can't see the holes in the net, you can't find any escapees in the cages, and yet - you endure much lower survival rates than you would expect.
You are looking all around.
What kind of visitors are there? Do you believe the FCR to be correct? Is it too low? Is it too high? When does FCR change?
If you start asking the guards about irregular behavior, you get no satisfactory answers.
And then you realize: the first candidates for the crime are.......
BIRDS‼
The greatest damage is done by birds, according to my experience.
Then, as soon as you realize that, you should take action. You should do something to prevent them from coming to the farm, or at least to prevent them from reaching the small fish in the cages.
Thus, you mount anti-bird nets with supporters in the middle, but then you realize that birds are not as stupid as they had been told! Because if 50 of them are mounted on one spot, the net will reach the surface of the water and so will the birds, and boom! Fingerlings are being eaten by hundreds and even thousands every night.
No noise is loud enough, no mirror is bright enough, and the worst thing is that eventually the net is stretched and torn off too fast, and boom! you have a bird-party in your cage.
To cut a long story short:
Our best solution was a combination of anti-bird net supporters that span as much as 20% of the cage's diameter, and a small mesh Dyneema net that will last much longer under the UV bad conditions and continuous stretching caused by the birds and the environment.
The combined solution was so good that survival rates were too high, and densities were too high, so we had to reduce stocking numbers. Could you imagine that?
If any of the weitter above is insighting you, if any more operational sollutions are needed, I do have many more simple ideas for comnplicated problems.
I think that this is the secrest of making things right.
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