Fishery-Independent Methods for Measuring Fish Populations Studied in Marianas

In mid-March 2010, a 30-day expedition by the NOAA Ship Oscar Elton Sette was completed in waters of Guam and the Commonwealth of the Northern Mariana Islands (CNMI) to study various fishery-independent technologies to measure the abundance of fish stocks. Scientists from the PIFSC Coral Reef Ecosystem Division (CRED) were joined by colleagues from the University of Hawaii Joint Institute for Marine and Atmospheric Research, the Northwest Fisheries Science Center (NWFSC), Woods Hole Oceanographic Institute, University of Western Australia, and University of Guam. Students from Guam public schools also participated in the cruise. The researchers conducted mapping surveys with the Sette and deployed 4 different types of instruments to measure fish density and composition around 6 banks and islands.

Three popular fishing banks south of Guam—Galvez Bank, a small bank south of Galvez Bank, and 11-Mile Reef—were completely mapped using a pole-mounted multibeam sonar. Then tests were carried out using 4 instruments to measure characteristics of the local fish community:

All methods are non-extractive methods of fish observation. During the cruise, the AUV capabilities were enhanced by adding the capability to transmit data to the surface during deployment.

Operations then moved to Rota, CNMI, where the Sette mapped the seafloor over depths of 40-300 m to add to previous multibeam coverage. BRUVS and AUV operations were also carried out. Farallon de Medinilla, a bank north of Saipan where military training operations are routinely conducted, was mapped using sonar, revealing previously unknown extents of this large bank that is of interest to CNMI fisheries management agencies. During the final segment of the cruise, BRUV and TOAD operations were conducted on the extensive banks west of Saipan. Data from 123 BRUVS deployments at Galvez Bank, Rota, and banks west of Saipan will be used by researchers from the University of Guam and University of Western Australia to compare fish populations and habitats in these areas. TOAD deployments west of Saipan documented a rare and protected coral, Euphyllia paraancora, in that area.

In addition to the science agenda, the Sette expedition featured outreach and education activities in Saipan and Guam. The research party also included a NOAA teacher-at-sea, who authored a blog during the cruise.