Density Estimation of Antarctic Krill in the South Shetland Island (Subarea 48.1) Using dB-Difference Method

Choi, Seok-Gwan; Chae, Jinho; Chung, Sangdeuk; Oh, Wooseok; Yoon, Eun–A; Sung, Gunhee; Lee, Kyounghoon

doi:10.3390/su12145701

Cited by 2 publications

(1 citation statement)

References 22 publications

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“…The densities by transect of E. pacifica in the SSL were calculated using the ∆MVBS, the Sv, and the nautical area scattering cross-section (NASC) of the 1 nautical mile (n•mile) interval of the elementary distance sampling unit. The density of E. pacifica was calculated via Equation (4) using the L with frequency of L, W-L relationship, and the NASC values obtained from the net sampling data [26,[43][44][45],…”

Section: Density Estimation Of E Pacificamentioning

confidence: 99%

Spatial Distribution of Sound Scattering Layer and Density Estimation of Euphausia pacifica in the Center of the Yellow Sea Bottom Cold Water Determined by Hydroacoustic Surveying

Kim

Kım

Kim

et al. 2022

JMSE

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The Yellow Sea Bottom Cold Water (YSBCW) refers to seawater with a water temperature of 10 °C or less found at the bottom of the center of the Yellow Sea. The spatiotemporal variability of the YSBCW directly affects the distribution of organisms in the marine ecosystem. In this study, hydroacoustic and net surveys were conducted in April (spring) to understand the spatial distribution of the sound scattering layer (SSL) and estimate the density of Euphausia pacifica (E. pacifica) in the YSBCW. Despite the shallow water in the YSBCW region, E. pacifica formed an SSL, which was distributed near the bottom during the daytime; it showed a diel vertical migration (DVM) pattern of movement toward the surface during the nighttime. The mean upward and downward swimming speeds around sunset and sunrise were approximately 0.6 and 0.3–0.4 m/min, respectively. The E. pacifica density was estimated in the central, western, and eastern regions; the results were approximately 15.8, 1.3, and 10.3 g/m2, respectively, indicating significant differences according to region. The results revealed high-density distributions in the central and eastern regions related to the water temperature structure, which differs regionally in the YSBCW area. Additional studies are needed regarding the spatial distribution of E. pacifica in the YSBCW and its relationship with various ocean environmental parameters according to season. The results of this study contribute to a greater understanding of the structure of the marine ecosystem in the YSBCW.

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Section: Density Estimation Of E Pacificamentioning

confidence: 99%

Spatial Distribution of Sound Scattering Layer and Density Estimation of Euphausia pacifica in the Center of the Yellow Sea Bottom Cold Water Determined by Hydroacoustic Surveying

Kim

Kım

Kim

et al. 2022

JMSE

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Antarctic Krill Biomass and Flux Measured Using Wideband Echosounders and Acoustic Doppler Current Profilers on Submerged Moorings

et al. 2022

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During austral summer 2018/2019, we deployed an array of six submerged moorings equipped with Nortek Signature100 integrated wideband echosounder and acoustic Doppler current profilers (ADCPs) on the continental shelf of the northern Antarctic Peninsula. Acoustic data from these instruments were used to classify targets, estimate water flow and the biomass of Antarctic krill (Euphausia superba), and quantify krill flux (biomass transport). We differentiated krill from other target aggregations using a supervised classification of data from the echosounder representing five wideband frequency bins spanning 68–113 kHz and two narrowband frequencies at 70 and 120 kHz. We estimated krill biomass using echosounder data collected at 120 kHz and water flow using the ADCP data. We estimated the biomass flux from the product of mean volumetric krill density and flow speed over a depth-integration range of 150 m. The overall mean krill areal biomass density based on hourly averages was 174 g⋅m–2 during the austral summer (December–March). Mean daily biomass decreased by an order of magnitude, from 300 to 31 g⋅m–2, over the sampling period, and fluctuated by nearly a factor of 4 above and below the local trend within weekly intervals. Mean current direction was along-shelf toward the west, and mean flow speed increased from ∼0.10 to 0.14 m⋅s–1 during the season. Krill flux was correlated with biomass variation, and the grand mean flux was 0.13 g⋅m–2⋅s–1. During the study period and in our approximately 1,300 km2 study area, average total biomass of krill was 116265 metric tons, and total cumulative krill biomass was 2.5 million tons. Our results demonstrate the utility of integrated echosounder-ADCP systems for quantifying krill flux in an important foraging area used by krill-dependent predators (seabirds and marine mammals) that breed nearby and highlight the scales of variability in a key prey resource required by these predators.

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Density Estimation of Antarctic Krill in the South Shetland Island (Subarea 48.1) Using dB-Difference Method

Cited by 2 publications

References 22 publications

Spatial Distribution of Sound Scattering Layer and Density Estimation of Euphausia pacifica in the Center of the Yellow Sea Bottom Cold Water Determined by Hydroacoustic Surveying

Spatial Distribution of Sound Scattering Layer and Density Estimation of Euphausia pacifica in the Center of the Yellow Sea Bottom Cold Water Determined by Hydroacoustic Surveying

Antarctic Krill Biomass and Flux Measured Using Wideband Echosounders and Acoustic Doppler Current Profilers on Submerged Moorings

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