Wildlife tourism including white shark cage-diving is growing in popularity, but these industries remain highly contentious amongst divers, conservationists and scientists alike. New tool helps judge the impact.
People eat a lot of fish. Different sex-changing fish can follow several signals that prompt them to change sex. Some change from female to male at a fixed size or age. Often, fisheries will only harvest fish over a certain size. This means catching more males because they are usually bigger, which then skews the population towards female. Not enough males are then available to fertilise all the eggs produced by the females.