Behavioral characteristics and spatio-temporal distribution of fish near the waters of Uljin marine ranch area in the East Sea using hydroacoustics

Abstract

The present study was conducted to investigate the behavior and distribution characteristics of fishes near an artificial reef close to the waters of Uljin marine ranch. A 200-kHz, dual-beam frequency transducer was attached to the side of a ship for acoustic measurements. The fish formed small groups in the bottom layer near the artificial reef around the afternoon-sunset period; at night, the fish did not form groups and remained individually scattered. During dawn-sunrise and morning, the fish formed groups again and were found near the upper and middle layers of the artificial reef. High density of fish occurred near the middle of the nautical zone during morning, afternoon-sunset, and dawn-sunrise, periods; at nighttime, the distribution was uniform across the entire zone. Moreover, the mean Nautical Area Scattering Coefficients (NASC, m2/nmi2) value was highest during dawn-sunrise at 400.2 m2/nmi2, similar during night and morning (100.5 m2/nmi2), and lowest during afternoon-sunset (20.1 m2/nmi2). The present study is expected to provide the background for understanding the behavioral characteristics of fish living near artificial reefs and estimating the density and biomass of fish.

Keywords

• Dual-beam
• Acoustic
• Artificial reef
• Fish distribution
• Behavior