A Comparative Assessment of Mid-Water Trawl and Deep Vision for Investigating Fishery Resources in the Coastal Waters off Jeju Island, Korea

Yong-Deuk Lee,Eirik Svoren Osborg,Kristoffer Løvall,Hyungbeen Lee,Cheol Park,Euna Yoon

doi:10.3390/app12041835

Yong-Deuk Lee, Eirik Svoren Osborg + Show 4 more

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https://doi.org/10.3390/app12041835

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Abstract

Acoustic-trawl surveys use trawl sampling to identify aquatic species. The Deep Vision stereo camera system collects images of fish passing through trawl extensions. We conducted a survey using Deep Vision with a mid-water trawl to identify and measure the lengths of domestic fish species in October 2020 and July 2021 in coastal waters off Jeju Island, Korea. We identified 86.4% of 22 species captured from images and estimated the lengths of 40% of the identified fish. A comparison of species numbers identified by mid-water trawl and Deep Vision revealed that, with the exception of three species with fewer than five individuals, identification was consistent. Our results indicate that the combined use of Deep Vision and mid-water trawl can be an eco-friendly and effective approach of examining the spatial distribution and size of fish species.

Highlights

Direct resource surveys for fisheries research include trawl, ichthyoplankton, underwater acoustic, and sighting surveys, along with scientific evaluation
A total of 22 species were caught through three mid-water trawls, among which 19 species were identified from 12,625 stereo images obtained using Deep Vision, indicating that 86% of the fish species caught in the trawl were identified by Deep Vision (Table 2)
The deviation of the populations between the two survey methods ranged from 0% to 2000%, with the largest difference of 2000% being obtained for chub mackerel and 1748% for skinnycheek lanternfish (Benthosema pterotum) in haul01, whereas Japanese flying squid (Todarodes pacificus), john dory (Zeus faber), Pacific rudderfish, and slender ribbonfish (Trachipterus ishikawae) in haul03 showed no difference in populations

Summary

Introduction

Direct resource surveys for fisheries research include trawl, ichthyoplankton, underwater acoustic, and sighting surveys, along with scientific evaluation. Trawl surveys quantify fishery catches primarily by using scientific research vessels and have been continuously conducted since 1930 to identify and evaluate the spatiotemporal distribution and resource quantity of major commercial fish species worldwide [3,4]. Given that the acoustic survey method using a scientific echosounder can estimate the spatiotemporal distribution and existing amounts of fishery organisms over large surveys area in a short period of time, research on major pelagic fish species such as North Pacific pollock and Atlantic mackerel has been widely conducted since the 1980s [5,6,7]. Mid-water trawl surveys, which catch pelagic fish detected by scientific echosounders, have a significant advantage in species identification when a single species is caught They are limited with respect to temporal and spatial analyses of biological resources, such as vertical distribution of specific fish species. To minimize damage to biological resources, eco-friendly studies are increasingly being conducted to identify ecological characteristics, such as the depth distribution of organisms, by installing underwater cameras on trawl gear or using autonomous underwater vehicles (AUVs) or underwater drones [11,12,13,14]

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