Studies in the Mariana Archipelago will Compare Alternative Methods of Assessing the Density of Local Fish Populations

February 11, 2010

Today a research expedition was launched to collect data vital to the management of coral reef ecosystems in the Mariana Archipelago. The 30-day cruise of the NOAA Ship Oscar Elton Sette is being conducted by a scientific crew of 20, including researchers from the Pacific Islands Fisheries Science Center (PIFSC), the Northwest Fisheries Science Center (NWFSC), the University of Hawaii Joint Institute for Marine and Atmospheric Research (JIMAR), and the University of Guam Marine Laboratory, and fisheries resource managers from Guam and the Commonwealth of the Northern Mariana Islands (CNMI). Chief Scientist in charge of research operations is PIFSC logistics specialist Scott Ferguson. During the cruise, data will be collected using a variety of methods to support the resource monitoring needs of local and national resource management agencies.

Potential survey areas in the Mariana Archipelago. 
            Depths estimated from available acoustic bathymetric data and satellite altimetry data.
Potential survey areas in the Mariana Archipelago. Depths estimated from available acoustic bathymetric data and satellite altimetry data.
A SeaBed AUV operated jointly by PIFSC and NWFSC. 
            Deployed above the seafloor, it follows the terrain to collect data for assessing fish resources and 
            characterizing the benthic habitat.
A SeaBed AUV operated jointly by PIFSC and NWFSC. Deployed above the seafloor, it follows the terrain to collect data for assessing fish resources and characterizing the benthic habitat.

The ship will carry out various studies of important fishery resources in Guam and CNMI. Included is a project to calibrate information on fish density using a variety of fishery-independent approaches, including extractive and non-extractive methods.

Prior to the fish density research, the scientists will use multibeam sonar to create high-resolution seafloor maps of one or more study areas in Guam and a similar number of areas in CNMI that include important fishery resources. Areas of interest that have been identified by scientists and managers in Guam and CNMI include Galvez Bank, Rota Island, Farallon de Medinilla (FDM), and a number of other shallow banks west of FDM Saipan, Tinian and Rota. Acoustic seafloor mapping will be required at most of these locations prior to use of additional survey equipment. The primary tool for seafloor mapping will be a Reson 8101ER multibeam echosounder deployed from Sette using a pole mount on the side of the ship. Optical data will be collected using a towed camera or autonomous underwater vehicle (AUV) to help characterize the habitat.

After the mapping is completed, two types of baited camera stations will be deployed from the Sette as non-extractive fisheries evaluation tools: the BotCam that has been developed by PIFSC and the BRUVS (Baited Remote Underwater Video System) from the Australian Institute of Marine Science. Data on density of fishes and other results from these video systems will be compared with extractive catch data collected by a chartered commercial fishing vessel. The fishing will be conducted during or immediately after the Sette's video surveys. In addition to the fishing and video surveys of fish density, acoustic data on biota in the water column will be collected using the Sette's EK60 sonar system to provide additional information about fisheries resources in the Mariana Archipelago.

Public education and outreach activities will be conducted aboard the Sette during a mid-cruise port call to Saipan, CNMI, and following the cruise in Guam.