This is the thirteenth in a multi-part series chronicling the 2012 trip to monitor the health of coral reefs in Raja Ampat, Indonesia. This year, Conservancy scientists are traveling to Raja Ampat alongside colleagues from CI and WWF.
This post was authored by Edy Setyawan, CI-Indonesia’s Kaimana marine conservation and science officer, and is cross-posted on CI’s blog.
Assessing fish populations is one of our main objectives on our monitoring trip in Raja Ampat—it’s a crucial part of evaluating the health of coral reefs here. On this trip, we’re particularly interested in comparing fish populations inside Marine Protected Areas (MPAs) with those outside of MPAs.
We have been fortunate enough to observe some of the larger, more elusive coral reef species. We’ve seen five species of sharks—mostly blacktip reef sharks patrolling the reef, though we were also fortunate enough to see the Tasselled Wobbegong, a “carpet shark” that lives on the seafloor and whose coloration patterns allow it to blend into the coral reef background. Other charismatic biodiversity sightings included Giant Mantas and Spotted Eagle Rays.
The diversity and biomass of different trophic (feeding) groups is an important indicator of a coral reef’s health and its ability to respond to and resist disturbances. It’s been encouraging to see many species of large carnivore fishes in Raja Ampat, including groupers, snappers, emperors, and sweetlips.
Herbivorous fishes that eat algae—like Surgeonfishes, Parrotfishes, and Rabbitfishes—are also abundant on many of the reefs we’ve surveyed. These species play a critical role in controlling algae and allow new corals to settle on the reef. We’ve also recorded schools of Bumphead Parrotfish that feed mainly on corals and help produce the white sand that ends up on beaches.
Small, cryptic fish—species that are generally difficult to see due to size or coloration, such as gobies—were also found in high diversity and abundance, though quantitative data was not collected because these fish are often hard to identify during monitoring surveys. These species are often snacks for larger fishes and are important in moving energy through coral reef ecosystems.
Though we have observed many species of fish from many different trophic groups, we have been concerned with the low numbers of larger fish, especially carnivores. On healthy reefs, top level predators should account for the bulk of the fish biomass.
In the 54 sites we’ve surveyed so far, this has not been the case. Unfortunately, this trend is holding up in MPAs as well as unprotected areas. Local governments and communities are hoping that the MPAs they have established in Raja Ampat will help many of these fish populations return to healthy sizes. Considering that the majority of coastal people in this region are largely dependent on their local fisheries for protein, protecting these reefs is critical for local food security.
Learn more about the Conservancy’s involvement in the game-changing Coral Triangle Initiative on Coral Reefs, Fisheries and Food Security.
(First image: Observing a school of surgeonfishes. First image credit: Edy Setyawan. Second image: A group of bumphead parrotfish. Second image credit: Sangeeta Mangubhai/TNC.)