Assessing juvenile Atlantic bluefin tuna schools in the Northwest Atlantic using sonar data and aerial imagery

• Published in: The Journal of the Acoustical Society of America
• Main Authors: Schroth-Miller, Madeline L, Weber, Thomas C.
• Format: Text
• Language: unknown
• Published: University of New Hampshire Scholars' Repository 2011
• Subjects: Oceanography and Atmospheric Sciences and Meteorology; Northwest Atlantic
• Online Access: https://scholars.unh.edu/ccom/648; https://doi.org/10.1121/1.3587674

Over the past 2 years, a feasibility study has been conducted in order to establish a methodology for assessing the biomass of juvenile Atlantic bluefin tuna (Thunnus thynnus). Over several days in August 2009, a 400 kHz Reson 7125 multibeam sonar installed on a commercial fishing vessel was used to collect acoustic backscatter from tuna schools. The multibeam sonar was oriented on the starboard side of the vessel to image a vertical slice of the water column. Because the fishing vessel was led to the tuna schools by a spotter plane, we were restricted to examining only near‐surface tuna schools that were visible from the air. The same spotter plane collected aerial images of the same schools that were examined with the multibeam sonar. The multibeam sonar data allowed us to estimate attributes such as the maximum depth, cross sectional area, and morphology of the fish schools in a vertical plane, while metrics such as the nearest neighbor distance and number of fish were estimated from the aerial photographs. Taken together, the sonar data and aerial imagery provide a viable methodology for assessing juvenile Atlantic bluefin tuna.