How pulse lengths impact fish stock estimations during hydroacoustic measurements at 70 kHz

Godlewska, M.; Colon, Michel; Jóźwik, A.; Guillard, Jean

doi:10.1051/alr/2011104

Cited by 32 publications

(23 citation statements)

References 29 publications

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“…Single Echo Detections (SED) were determined using the Sonar5‐Pro software with the following settings: a pulse length ratio between 0.8 and 1.3, a maximum gain compensation of 3 dB (one way) and a sample angle standard deviation 0.3 degree (Godlewska et al. ; Guillard et al. ).…”

Section: Methodsmentioning

confidence: 99%

Including 38 kHz in the standardization protocol for hydroacoustic fish surveys in temperate lakes

Mouget

Goulon

Axenrot

et al. 2019

Remote Sens Ecol Conserv

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Hydroacoustics has become a requisite method to assess fish populations and allows to describe the relationships of fish with other elements of the aquatic ecosystem. This nonintrusive method is currently an integral part of the sampling procedures recommended for fish stock assessment by the Water Framework Directive and has been standardized by the European Committee for Standardization [CEN (2014) CSN EN 15910 ‐ Water quality ‐ Guidance on the estimation of fish abundance with mobile hydroacoustic methods, Category: 7577 Water quality. Biological.]. In Europe, hydroacoustic surveys are performed in freshwater using different frequencies. Consequently, there is a need to evaluate if survey results can be compared. This study aimed to carry out in situ comparisons at the 38 kHz frequency (noted f) with two other commonly used frequencies, 70 and 200 kHz. The 38 kHz frequency has seldom been compared with other frequencies in freshwater although it is widely used worldwide, especially in the Great Lakes of North America and in Sweden. In 2016, hydroacoustic data were acquired in Lakes Annecy and Bourget using methods validated in previous studies that compared the frequencies 70, 120 and 200 kHz. This study showed similar density and biomass estimations as a function of frequency, density(f) and biomass(f), between the frequencies studied for low to moderate fish densities. For higher fish densities, the results were more variable and need to be verified. Fish density(f) and biomass(f) estimations sometimes exhibit differences between frequencies, which is not fully in agreement with theoretical calculations. The aim of this study was to evaluate frequency comparisons in practise. However, if the differences on acoustic metrics, density(f) or biomass(f) between frequencies were occasionally statistically significant, the differences were small enough to be considered negligible for fish population management. These analyses led to better knowledge of the responses from fish in temperate lakes for the studied frequencies. Our findings should be considered when revising the CEN standard.

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Section: Methodsmentioning

confidence: 99%

Including 38 kHz in the standardization protocol for hydroacoustic fish surveys in temperate lakes

Mouget

Goulon

Axenrot

et al. 2019

Remote Sens Ecol Conserv

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“…A GPS system was used to record boat positions. The collection parameters were a pulse-length of 0.256 ms (Godlewska et al, 2011) and 5 pulses per second. Sounder calibrations were performed annually in a large basin (IFREMER, Brest) according to the standard protocol of Foote et al (1987), and the system was stable (gain variation b 0.4 dB).…”

Section: Methodsmentioning

confidence: 99%

Is the fishery of the introduced Tanganyika sardine (Limnothrissa miodon) in Lake Kivu (East Africa) sustainable?

Guillard¹,

Darchambeau²,

Mulungula³

et al. 2012

Journal of Great Lakes Research

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Limnothrissa miodon, a small pelagic clupeid fish introduced at the end of the 1950s into Lake Kivu, became an important resource for the human populations of this area. The total stock of pelagic fish populations of this lake was estimated in 2008 by two hydroacoustic surveys, using an EK60 split-beam sounder (frequency 70 kHz). The total fish stocks were estimated to be approximately 5000 t in the rainy season and 6000 tons in the dry season. These values are similar to previous estimations performed in the 1980s. During 2008, the stock did not fluctuate throughout the seasons; however, the spatial distributions were different in the two hydrological seasons. Interestingly, the L. miodon stock has appeared to remain stable over the last two decades, which suggests that the pelagic fishery in Lake Kivu has not been overexploited and that it is sustainable.

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“…Acoustic measurements on fish populations can be affected by the sound frequency and pulse duration (Knudsen, Larsson & Jakobsen, 2006;Godlewska et al, 2011), but it has been shown that parameters lying within the range of this study produce unbiased fish biomass estimates (Guillard, Lebourges-Dhaussy & Brehmer, 2004;Godlewska et al, 2009Godlewska et al, , 2011. Nevertheless, we analysed the effects of the different sound frequencies and pulse durations on the reliability of the fish density estimates using the Sawada index N v (Sawada, Furusawa & Williamson, 1993)…”

Section: Hydroacousticsmentioning

confidence: 91%

“…Acoustic measurements on fish populations can be affected by the sound frequency and pulse duration (Knudsen, Larsson & Jakobsen, 2006; Godlewska et al. , 2011), but it has been shown that parameters lying within the range of this study produce unbiased fish biomass estimates (Guillard, Lebourges‐Dhaussy & Brehmer, 2004; Godlewska et al.…”

mentioning

confidence: 84%

Strong correspondence between gillnet catch per unit effort and hydroacoustically derived fish biomass in stratified lakes

Emmrich

Winfield

Guillard³

et al. 2012

Freshwater Biology

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The NERC and CEH trademarks and logos ('the Trademarks') are registered trademarks of NERC in the UK and other countries, and may not be used without the prior written consent of the Trademark owner. e-mail: emmrich@igb-berlin.de 2 Summary 1) Sampling of lake fish assemblages is a challenging task in fish science and the information obtained strongly depends on the choice of sampling gear. The use of more than one sampling technique is generally preferred in order to achieve a comprehensive view on fish assemblage structure. Therefore, knowledge of whether catches between fishing gears are comparable is crucial.2) We compared catches in benthic multi-mesh gillnets with fish biomass estimates obtained by vertical hydroacoustics in 18 European lakes strongly varying in morphometry and trophic status. Separate analyses were conducted for different depth strata and for several fish-length thresholds to account for depth-and sizeselective gillnet catches.3) Gillnet catches and hydroacoustically obtained fish biomass estimates were significantly correlated. The strength of correlations was independent of the fishlength thresholds applied, but varied across different depth strata of the lakes, with the strongest correlations occurring in the shallow strata.4) The results support the applicability of vertical hydroacoustics for the quantification of fish biomass in stratified lakes. Survey designs combining hydroacoustics with limited gillnetting at sampling dates shortly one after the other, the latter for the purpose of inventory sampling only, are a cost-effective strategy for sampling fish assemblages in lakes. However, gillnet sampling does not provide reliable fish density estimates in very deep lakes with separate, pelagic-dwelling fish assemblages.

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How pulse lengths impact fish stock estimations during hydroacoustic measurements at 70 kHz

Cited by 32 publications

References 29 publications

Including 38 kHz in the standardization protocol for hydroacoustic fish surveys in temperate lakes

Including 38 kHz in the standardization protocol for hydroacoustic fish surveys in temperate lakes

Is the fishery of the introduced Tanganyika sardine (Limnothrissa miodon) in Lake Kivu (East Africa) sustainable?

Strong correspondence between gillnet catch per unit effort and hydroacoustically derived fish biomass in stratified lakes

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