A Pilot Study on the Application of Acoustic Data Collected from a Korean Purse Seine Fishing Vessel for the Chub Mackerel

This paper describes the first use of acoustic data collected during normal fishing operations from a South Korean commercial fishing vessel. Acoustic data (120 kHz) were collected from a purse seine fishing vessel while targeting chub mackerel (Scomber japonicus) between 13 September and 7 October 2014 in the southern West Sea and near Jeju Island. Acoustic backscatter data from 21 fishing events were used to delineate fish school characteristics and to estimate the chub mackerel biomass which was compared with the catch. With regard to the fish school description, the volume back scattering strength (SV) and thickness of the fish schools presented differently. The average and standard deviation of SV was −47.3 ± 2.1 dB. The fish lengths varied greatly and some schools were inordinately long (average and standard deviation length of 137.0 ± 329.6 m). The fish school area largely altered. The average distributional depth and the distance between fish school and sea bottom were 31.8 m and 42.7 m, respectively, indicating that the fish schools attracted by light were mainly located close to the water surface. On average, the chub mackerel biomass was 1.7 times larger than the catch. The correlation between the chub mackerel biomass and the catch was low positive (r = 0.3, p < 0.05). This paper presented that available echo sounders installed fishing vessels can be used for helping in the chub mackerel resources management in South Korea.