Displaying the remarkable ability to change its sex, the red grouper is a protogynous hermaphrodite, starting its life as a female, and later changing to a male. Females reach sexual maturity after four to six years of age, before participating in spawning events between January and April, with females and males simultaneously releasing millions of eggs and sperm into the water. Around 30 hours after fertilisation, the eggs hatch and the larval fish begin life as part of the zooplankton, floating passively in the ocean’s currents. After a further 35 to 50 days of growth, the benthic young fish will start to feed on small, ground-dwelling crustaceans amongst seagrasses (4). Heavily predated by larger fish, it is only once they reach a moderate size that the young groupers move away from the shelter of the grasses towards deeper, more dangerous waters. If the red groupers successfully avoid predation they may change to males after 7 to 14 years, and possibly live to a staggering 30 years of age (2) (5).
Growing over a metre in length, these dominating marine predators are high-up the food chain. Opportunistically preying upon a variety of crabs, shrimps, octopuses and fish, such as snappers and parrotfish, the red grouper has a significant influence on the abundance of other reef-dwelling species and the overall health of the fragile coral reef ecosystem (2) (6). Juvenile red groupers are important prey for other predatory fish, such as mackerels and jacks (6).