The importance of sound fisheries management to maintain healthy coral reefs (and the importance of healthy coral reefs to a robust fishing program) has been known to Polynesians for a long time. An interesting local scientific research program now sheds light on how this works – and illustrates the importance of employing traditional knowledge to maintain a healthy fishing environment.
After the Crown-of-Thorns starfish outbreak and Cyclone Oli, the coral reefs on Tetiaroa and Moorea were in very bad shape. Everyone wondered if they would recover. Scientists from the Long-term Ecological Research program (LTER), working at the UC Berkeley Gump Research station, decided to use this as an opportunity to see how a coral reef responds to a major stress like this.
The LTER scientists found that coral larvae, still abundant in planktonic form, were trying to settle on old dead coral surfaces, but brown algae was settling faster. Soon most of the surface of the dead reef was covered with algae, blocking the return of coral to the system. But then, presumably because these islands still have a robust fish population, the herbivorous fish species with plenty of algae to eat, began to multiply. Their populations grew until they ate up most of the algae and created space for the coral larvae to settle. And the coral came back. The system slowly shifted until the outer slopes of the reefs on Tetiaroa and Moorea were covered with tiny corals.
The key to the recovery of the reefs was a healthy fish population, particularly the herbivorous fish like Surgeonfish and Parrotfish. These also happen to be the species that local people like to eat the most, so it raises a problem.