Application of dual-beam and split-beam target tracking in fisheries acoustics

Ehrenberg, John E.; Torkelson, Thomas C.

doi:10.1006/jmsc.1996.0044

Cited by 74 publications

(20 citation statements)

References 4 publications

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“…Because behavioral changes in fish aspect can cause wide variations in TS (Gunderson 1993), a range of ±3 decibels was applied to the estimated TS of age‐0 kokanee. This range corresponded to the average standard deviation of TS of individual fish in our dataset and was consistent with values reported in the literature (MacLennan and Simmonds 1992; Ehrenberg and Torkelson 1996; Ransom et al 1999). To describe temporal patterns in vertical distribution of kokanee we computed median, 25th and 75th percentiles, and the range of depths occupied by kokanee during each sampling interval.…”

Section: Methodssupporting

confidence: 92%

Do Predators Influence the Distribution of Age-0 Kokanee in a Colorado Reservoir?

Hardiman

Johnson

Martinez

2004

Transactions of the American Fisheries Society

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Seasonal changes in reservoir conditions such as productivity, light, and temperature create spatiotemporal variation in habitat that may segregate or aggregate predators and prey, producing implications for the distribution, growth, and survival of fishes. We used hydroacoustics to document the diel vertical distribution of age‐0 kokanee Oncorhynchus nerka relative to environmental gradients at Blue Mesa Reservoir, Colorado, during May–August of 2002. Temperature, light, and zooplankton density profiles were examined relative to foraging conditions for kokanee and their primary predator, lake trout Salvelinus namaycush. Age‐0 kokanee displayed large diel vertical migrations in May despite the lack of an energetic advantage before reservoir stratification. Age‐0 kokanee minimized near‐surface foraging at this time, perhaps to avoid predation by visual predators, such as lake trout, in the well‐lit surface waters. Strong reservoir stratification in midsummer appeared to provide a thermal refuge from lake trout that the kokanee exploited. By August vertical migrations were shallow and most kokanee remained in the epilimnion throughout the day. Although the energetic implications of the late‐summer strategy are unclear, it appears that kokanee were responding to changes in their predator environment. A robust model for kokanee diel vertical migration across a range of systems should include a predator avoidance component.

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Section: Methodssupporting

confidence: 92%

Do Predators Influence the Distribution of Age-0 Kokanee in a Colorado Reservoir?

Hardiman

Johnson

Martinez

2004

Transactions of the American Fisheries Society

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“…Echo counting was used when the single target echoes did not overlap, which generally occurred when the fish were at lower densities (Simmonds & MacLennan ). A fish track (FT) was considered a combination of at least three single targets from a single fish (Ehrenberg & Torkelson ) (Fig. ).…”

Section: Methodsmentioning

confidence: 99%

Seasonal and diel changes in fish distribution in a tropical hydropower plant tailrace: evidence from hydroacoustic and gillnet sampling

Loures

2015

Fisheries Management Eco

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Hydropower plant operation can lead to direct impacts on fish near the dam, causing injuries and death. In Brazil, it is more common to observe these impacts in the tailrace. To understand temporal and spatial variations in fish abundance in the tailrace, to assist plant operation management, surveys were performed in Três Marias Hydropower Plant using hydroacoustics and multimesh gillnets. Data were collected in the tailrace backwater over 1 year, during 18 field trips, each covering a 24‐h cycle with six sampling intervals. A greater abundance of fish was found in the tailrace during the wet season, mainly explained by total discharge. More fish were detected by hydroacoustics and gill nets during night sampling. Siluriformes, which are known to exhibit nocturnal habits, were the predominant species in both dry and wet seasons. Thus, damaging operational procedures for fish should be planned in the dry season, low‐abundance period.

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“…Comparison of our relationship for the vertical mode of TS = 7.07 log 10 ( V ) – 43.48 with the relationship provided by Ostrovsky et al () of TS = 7.45 log 10 ( V ) – 44.67 shows good consistency. The small difference in coefficients could be attributed to the fact that split‐beam echosounders (used in present work) are less influenced by additive noise than dual‐beam echosounders (Ehrenberg and Torkleson ).…”

Section: Discussionmentioning

confidence: 85%

Quantification of methane bubbles in shallow freshwaters using horizontal hydroacoustical observations

Frouzová

Tušer

Stanovský

2015

Limnol. Oceanogr. Methods

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Methane represents an important greenhouse gas, and its ebullition is a significant way of releasing gas from bottom sediments of shallow fresh waters to the atmosphere. Estimation of ebullition is complicated because of high spatiotemporal variability; however, a hydroacoustical survey represents an effective method for quantifying it. Commonly used vertical beaming in deep waters can be quite limited in very shallow waters. This study was thus aimed to investigate the possibility of using a horizontally oriented sonar beam for gas bubble quantification. Artificially prepared methane bubbles of various sizes, ranging from 2.5 to 905 × 10−3 mL (1.7–12 mm of equivalent spherical diameter), were released from a depth of 6 m in a freshwater reservoir. The acoustic target strength (TS) of these bubbles was observed using both the vertical and horizontal beams of a 120 kHz frequency split‐beam sonar. TS obtained in both the vertical and horizontal modes increase with growing bubble size. However, for identical bubble size, the vertical observation gives stronger TS than the horizontal one. Further, TS distribution around mean value is wider with an increase in bubble size, and this distribution is greater in case of the horizontal mode of observation than vertical. It was observed that during bubble rise TS changes for both the vertical and horizontal mode of observation lie within the range of standard deviation of TS measurement; hence, depth is not relevant for TS regression models used in depth up to 6 m.

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Application of dual-beam and split-beam target tracking in fisheries acoustics

Cited by 74 publications

References 4 publications

Do Predators Influence the Distribution of Age-0 Kokanee in a Colorado Reservoir?

Do Predators Influence the Distribution of Age-0 Kokanee in a Colorado Reservoir?

Seasonal and diel changes in fish distribution in a tropical hydropower plant tailrace: evidence from hydroacoustic and gillnet sampling

Quantification of methane bubbles in shallow freshwaters using horizontal hydroacoustical observations

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