Underrepresentation of eels in AGRRA and REEF fish surveys in Bonaire
Eels play an important role in coral reef ecosystems as part of nuclear hunting groups and as top predators. They are often underrepresented in fish population surveys due to their hiding behavior. There is consensus among the scientific community that most visual survey methods are not able to give an accurate measurement of the eels in the area surveyed. This study conducted surveys using the methods of two environmental and research organizations: the Reef Environmental Education Foundation (REEF) and the Atlantic and Gulf Rapid Reef Assessment (AGRRA). The surveys conducted in this study looked specifically for eels and the results were compared with historic data collected using both methods. This comparison indicates how accurate these methods are at representing eel populations in Bonaire. Using the same protocols but looking specifically for eels this study found eels more frequently and in greater numbers than the REEF surveys from the online database. The density of eels found using the AGRRA protocol was higher but not significantly different than the density reported in a similar study from 2011. The conclusions from this study are that the REEF methodology, while excellent at reporting species diversity, in not a very accurate method when it reports eel densities. The AGRRA method is about as accurate as a visual survey method can be for eels and allows the data to be reported in a much more usable manner.
This student research was retrieved from Physis: Journal of Marine Science XIII (Spring 2013)19: 39-44 from CIEE Bonaire.