Sex changing fish anyone?

Did you know that many species of fish are ambisexual? They can be either male or female depending on lifecycle and environmental influences.

Two Bay of Plenty Polytechnic scientists are working on a research project that could have implications for the international aquaculture industry.

Dr Lindsay Skyner, from the Polytechnic’s Animal Care department, and Dr Simon Muncaster, from the Marine Studies department, have been collaborating to get to the bottom of the sex changing fish mystery.

“Many species of fish are ambisexual,” says Dr Skyner. “That is, they can change sex from male to female (protandry), female to male (protogyny), or even from one sex to another then back again. Some fish can change sex several times over their life time – some can even have mixed sexual organs, called ovotestes.”

Dr Skyner has extensive experience in studying animal behaviour so it was a great opportunity to partner with Dr Muncaster who has a PhD in reproductive physiology in a study to understand and control reproduction in farmed fish species.

While other research projects around the world have focussed on the physiological aspects of sex change in fish, the Polytechnic pair are including an additional focus on the fish behaviour which is thought to trigger the whole event.

“One of the reasons we are interested in understanding the sex change process is that many high value fish species around the world change sex as part of their lifecycle,” says Dr Muncaster. “In a farming situation it is important to control reproduction for efficient production. This involves maintaining optimal breeding ratios of male and female fish.

“Obviously if fish start changing sex in captivity then this can have negative implications for farmers. Therefore it is important to understand what initiates the process and how it proceeds so that we can apply this knowledge. We can investigate this using the humble spotty as a model species.”

Marine studies students have helped the pair with video recordings to monitor behaviour and setting up experiments. They hope to publish their preliminary data later in 2013.