BIOMASS AND SPATIAL DISTRIBUTION ESTIMATES OF HAIRTAIL (TRICHIURUS JAPONICUS) IN THE NORTHERN WATERS OF TAIWAN

Abstract

In the East China Sea, the population structure of hairtail has varied for the last 20-30 years because of high intensity of fishing pressure. Therefore, for the sustainable management of hairtail, a conservative measure is required on the basis of scientific research. Acoustic transect line survey was conducted from 10 to 17 Dec 2019 in the northern sea of Taiwan along with 7 pole and line fishing and 1 trawl sampling to estimate the biomass and spatial distributional characteristics of hairtail. Two fishing gears had very different results. Thus, for hairtail allocation, three interpretation scenarios of low, medium, and high in total backscatter were considered. Consequently, the hairtail biomass in three scenarios were to be 5286 (30%), 7048 (40%), and 8810 tons (50%), respectively. Acoustic data from a long coastal line and three lines at a similar location were extracted to examine fish distributional characteristics. Lastly interpolated water temperature and salinity with backscatters were compared. This study can support in designing an integrated acoustic trawl survey next year, as well as the sustainable hairtail resource management.