September 2, 2010

Why doesn’t Reef Check Monitor Angelfish or Surgeonfish?


The tropical protocol was designed to use proxy indicators, typically at the family level, to indicate the health of coral reefs with respect to human impacts. It was designed to extract the maximum information about reef health in the minimum time and by trained volunteers. Reef Check surveys also provide a lot of ecological information about the reef, but the protocol was not designed as an ecological survey per se.

Two global fish indicators, the Grouper and the Parrotfish families were chosen to represent predators and herbivores that are targeted by fishermen for food. Butterflyfish were chosen to help track the impacts of the marine aquarium trade on reefs. Unfortunately, the more indicators that are included in the Reef Check protocol, the more training is needed and the greater chance of error by volunteers. By restricting the taxonomic detail and the number of indicators to less than ten fish and ten invertebrates, this makes Reef Check accessible to well trained high school students or fishermen.

Angelfish and Surgeonfish would be excellent indicators of coral reef health because the former are targeted by aquarium fishermen and the latter are an important food fish. However, we don’t include them in Reef Check because we had to make a decision about what makes the best indicators. If we included all the possible indicators then we are back to a standard scientific survey requiring many weeks of training that would no longer be suitable for volunteers. From this perspective, the Butterflyfish are proxies for Angelfish with respect to the marine aquarium trade and the Parrots are proxies for the Surgeonfish from the perspective of an herbivore that is targeted as a food fish. Of course they are not perfect proxies because there are many differences in their behavior, feeding and life history strategies. But together with the other fish, invertebrate, algal and non-living indicators, the Reef Check protocol has proven to provide a very useful measure of reef health. For Reef Check teams that have the taxonomic skills and interest, we welcome you to add one or two more indicators that you feel are important in your area, however, we don’t include those in our global database.