Studies by Sakakura and Tsukamoto (2003) segmented 3 sizes of yellowtail kingfish juveniles 12 days after they hatch. These are 42% small (6-8mm), 50% medium (8-10mm) and 8% large (10-12mm). of the 8% of the population of large juveniles, about 20-30% showed aggression towards the small juveniles.
This aggression involves chasing and canibalism.
Aggression was not shown towards the medium juveniles.
Grading of the large juveniles from the population prevents this ‘bullying’ however, the small juveniles appear to be on a degenerative “trajectory” anyway.
Sakakura and Tsukamoto found that the best way to handle yellowtail kingfish juveniles was at night when they become semi-dormant and float towards the surface of the tank.
Further information can be found in Sakakura and Tsukamoto’s paper titled Size hetrogeneity, growth potential and aggression in juvenile yellowtail kingfish.
Tags: yellowtail kingfish
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The loss caused by this agression has resulted in high price for the yellowtail kingfish. Can the tremendous loss caused by this agression can be overcomed by ways such as separating large juveniles from the small? Do hatcheries currently have any solution for this problem? Is there any existing technique which is practiced to separate large juveniles from small juveniles?
Mihir- it will be interesting to see the outcomes of one of the groups to see if any of the jaw deficiency work they are doing can be adapted to lower the aggression in the fish.
Is it true in what you say, that yellowtail kingfish are priced so high because of the losses in fish experienced in its juvenile stage. This is very interesting, because as a consumer, I would want as much research done as possible to lower the market prices of this fish.