Evaluating a Teranas Natural Reef off Malaysia Using a Multibeam Echosounder: A Method to Support Artificial Reefs
Razak Zakariya and Lenny Sharinee Sakai
Abstract.—In recent years, as reported by the Malaysian Department of Fisheries, the decline in demersal fish resources is due to excessive exploitation. This indicates that management and protection of these resources and their habitat are required. Teranas is identified as important critical marine habitat and locally in Malay is defined as a hard rock substrate on the seabed. Teranas can appear in all shapes and sizes, depths, and locations. The combination of these various bottom features often make a teranas attractive to fish. The objective of this study is to detect a teranas so that it can be located and managed through mapping. Sonar in the form of a multibeam echosounder was used to map a teranas with a combination of bathymetry and water column features to identify the signature for teranas. The result produced a signature library to readily identify a teranas with the multibeam echosounder. An important factor in determining the signature for the teranas was the seabed structure and its associated marine life. Bathymetry identified the seabed structure, and the water column characteristics helped verify the presence of marine life. Fishing and visual surveys with scuba diving were also conducted to verify the effectiveness of the multibeam echosounder to identify the teranas. These study results can be used as an aid for planning and managing a teranas to help sustain the associated fisheries resources. Moreover, since a teranas is similar in structure and position to an artificial reef, the multibeam echosounder, when coupled with visual diver-based surveys and fishing effort, could be used to identify the extent and marine fauna associated with an artificial reef. This research will help in providing strategic location selection for artificial reef placement.