On the live transport analysis boxes 2 and 3 were opened. These contained 10,000 and 40,000 larvae respectively. The temperature of these was still 3-4 degrees below the ambiant water temperature that was added.
The survival rate of 25.2 per cent was as expected on box 2, which had been aerated at too vigorous an aeration rate, causing excessive bubbling and initial stress to the larvae. The survival rate on box 3 was over 3 times higher at 76 per cent, which can be attributed to a lower level of air pressure used in aeration of the water.
The clear larval rearing tank had almost 100 per cent loss by morning feed and the trial was terminated. As it was a single tank and had not been conducted as a trial with a control and duplicate system the exact reason for such high mortality rates is unknown. This is definitely a trial that will need redoing, undertaking a proper scientific approach to review if there is no benefit to this system or if it was just a coincidental high mortality rate.
The high density tanks seem to be at a much higher level of survival than was expected. However, we are approaching the 7-10 day period which has previously seen significant losses in our earlier trials.
These tanks will be sampled over the next 3 days to ascertain a more accurate mortality rate that this higher stocking density has achieved.
The egg collection was just under 500,000 eggs.
Further Reading
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