Sterilising farmed fish offers the aquaculture industry a number of benefits. For farmers themselves, it can prevent fish from becoming sexually mature – desirable since maturation reduces flesh quality and makes fish more susceptible to diseases. Sterilisation can also restrict their environmental impact in preventing farmed genes, which are often suboptimal for a life in the wild, from being introduced into wild populations by escapees. The current sterilisation method of choice for aquaculture is to induce triploidy.
The process itself is fairly straightforward. Fertilised eggs are exposed to either high pressure or high temperature, disrupting chromosome movement during meiosis (cell division). Treated eggs retain more chromosomes than they normally would do – three instead of just two – rendering the animal infertile. Triploidisation as a sterilisation method has a number of benefits. It is already used in terrestrial agriculture systems. Most bananas we eat and seedless watermelons, for example, are triploid. It can also sterilise fish en masse – an essential element for commercial application. Other methods, such as surgical sterilisation, are much more labour intensive – and really only suitable for sterilising a small number of fish at a time.
As with everything, inducing triploidy is not perfect...
This article was written for (and can be read in full at) The Fish Site.