The R package EchoviewR for automated processing of active acoustic data using Echoview

Harrison, Lisa-Marie Katrina; Cox, Martin J.; Skaret, Georg; Harcourt, Robert

doi:10.3389/fmars.2015.00015

Cited by 17 publications

(10 citation statements)

References 20 publications

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“…Lower value thresholds (-44 to -41 dB re 1 m -1 ) removed krill echoes ( S1 Fig for the selection of S v noise threshold). Acoustic data processing was carried out using Echoview software (version 11.1, Echoview, Hobart, Australia), automated via COM-objects using EchoviewR (version 1.1.18; [ 16 ]). Sound speed and absorption coefficients were applied to each transect segment and were calculated from the nearest voyage CTD station using the harmonic mean of sound speed calculated from CTD samples between 10 m and 250 m water depth.…”

Section: Methodsmentioning

confidence: 99%

Two scales of distribution and biomass of Antarctic krill (Euphausia superba) in the eastern sector of the CCAMLR Division 58.4.2 (55°E to 80°E)

et al. 2022

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Regular monitoring is an important component of the successful management of pelagic animals of interest to commercial fisheries. Here we provide a biomass estimate for Antarctic krill (Euphausia superba) in the eastern sector of the Commission for the Conservation of Antarctic Marine Living Resources (CCAMLR) Division 58.4.2 (55°E to 80°E; area = 775,732 km2) using data collected during an acoustic-trawl survey carried out in February and March 2021. Using acoustic data collected in day-time and trawl data, areal biomass density was estimated as 8.3 gm-2 giving a total areal krill biomass of 6.48 million tonnes, with a 28.9% coefficient of variation (CV). The inaccessibility of the East Antarctic makes fisheries-independent surveys of Antarctic krill expensive and time consuming, so we also assessed the efficacy of extrapolating smaller surveys to a wider area. During the large-scale survey a smaller scale survey (centre coordinates -66.28°S 63.35°E, area = 4,902 km2) was conducted. We examine how representative krill densities from the small-scale (Mawson box) survey were over a latitudinal range by comparing krill densities from the large-scale survey split into latitudinal bands. We found the small scale survey provided a good representation of the statistical distribution of krill densities within its latitudinal band (KS-test, D = 0.048, p-value = 0.98), as well as mean density (t-test p-value = 0.44), but not outside of the band. We recommend further in situ testing of this approach.

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Section: Methodsmentioning

confidence: 99%

Two scales of distribution and biomass of Antarctic krill (Euphausia superba) in the eastern sector of the CCAMLR Division 58.4.2 (55°E to 80°E)

et al. 2022

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“…The echosounder operated at 38 and 120 kHz for the duration of the voyage with a pulse duration of 1.024 ms, a pulse repetition rate of one ping per second and a 7° beam width. Acoustic data were processed using Echoview v6.1 (Myriax, Hobart, Australia) and the R package EchoviewR 56 . Background and time varied gain noise was removed using the method outlined in De Robertis and Higginbottom 57 .…”

Section: Methodsmentioning

confidence: 99%

The characteristics of krill swarms in relation to aggregating Antarctic blue whales

Miller

Potts²,

Cox

et al. 2019

Sci Rep

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We model the presence of rare Antarctic blue whales (Balaenoptera musculus intermedia) in relation to the swarm characteristics of their main prey species, Antarctic krill (Euphausia superba). A combination of visual observations and recent advances in passive acoustic technology were used to locate Antarctic blue whales, whilst simultaneously using active underwater acoustics to characterise the distribution, size, depth, composition and density of krill swarms. Krill swarm characteristics and blue whale presence were examined at a range of spatiotemporal scales to investigate sub meso-scale (i.e., <100 km) foraging behaviour. Results suggest that at all scales, Antarctic blue whales are more likely to be detected within the vicinity of krill swarms with a higher density of krill, those found shallower in the water column, and those of greater vertical height. These findings support hypotheses that as lunge-feeders of extreme size, Antarctic blue whales target shallow, dense krill swarms to maximise their energy intake. As both Antarctic krill and blue whales play a key role in the Southern Ocean ecosystem, the nature of their predator-prey dynamics is an important consideration, not only for the recovery of this endangered species in a changing environment, but for the future management of Antarctic krill fisheries.

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“…These data were then converted into Echoview line (.evl) and region (.evr) files. Furthermore, a list of transect start and stop times and associated echosounder files was created for each vessel and used by an R-script that, transect-by-transect, loaded the appropriate echosounder files into the Echoview template, loaded the previously created line and region files, directed Echoview to process as per the template, and then exported the integrals into files for subsequent processing (EchoviewR; Harrison et al, 2015).…”

Section: Acoustic Data Processingmentioning

confidence: 99%

OUP accepted manuscript

Krafft

Macaulay

Skaret

et al. 2021

Journal of Crustacean Biology

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Estimates of the distribution and density of Antarctic krill (Euphausia superba Dana, 1850) were derived from a large-scale survey conducted during the austral summer in the Southwest Atlantic sector of the Southern Ocean and across the Scotia Sea in 2018-19, the '2018-19 Area 48 Survey'. Survey vessels were provided by Norway, the Association of Responsible Krill harvesting companies and Aker BioMarine AS, the United Kingdom, Ukraine, Republic of Korea, and China. Survey design followed the transects of the Commission for the Conservation of Antarctic Marine Living Resources synoptic survey, carried out in 2000 and from regular national surveys performed in the South Atlantic sector by the U.S., China, Republic of Korea, Norway, and the U.K. The 2018-19 Area 48 Survey represents only the second large-scale survey performed in the area and this joint effort resulted in the largest ever total transect line (19,500 km) coverage carried out as one single exercise in the Southern Ocean. We delineated and integrated acoustic backscatter arising from krill swarms to produce distribution maps of krill areal biomass density and standing stock (biomass) estimates. Krill standing stock for the Area 48 was estimated to be 62.6 megatonnes (mean density of 30 g m -2 over 2 million km 2 ) with a sampling coefficient variation of 13%. The highest mean krill densities were found in the South Orkney Islands stratum (93.2 g m -2 ) and the lowest in the South Georgia Island stratum (6.4 g m -2 ). The krill densities across the strata compared to those found during the previous survey indicate some regional differences in

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The R package EchoviewR for automated processing of active acoustic data using Echoview

Cited by 17 publications

References 20 publications

Two scales of distribution and biomass of Antarctic krill (Euphausia superba) in the eastern sector of the CCAMLR Division 58.4.2 (55°E to 80°E)

Two scales of distribution and biomass of Antarctic krill (Euphausia superba) in the eastern sector of the CCAMLR Division 58.4.2 (55°E to 80°E)

The characteristics of krill swarms in relation to aggregating Antarctic blue whales

OUP accepted manuscript

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