The Back-scattering of Acoustic Waves in Water by an Obstacle II: Determination of the Reflectivities of Solids using Small Specimens

Haslett, R.W.G.

doi:10.1088/0370-1328/79/3/313

Cited by 18 publications

(10 citation statements)

References 5 publications

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“…Because of the large density and sound speed contrasts of gas and water, the echo intensity of a fish primarily depends on the presence or absence of a gas-filled swimbladder (Haslett 1962;Foote 1980a). Contributions of fish flesh and other organs to the total backscatter of a fish are minimal compared with the contributions from the swimbladder.…”

Section: Discussionmentioning

confidence: 99%

Acoustic characteristics of forage fish species in the Gulf of Alaska and Bering Sea based on Kirchhoff-approximation models

Gauthier¹,

Horne²

2004

Can. J. Fish. Aquat. Sci.

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Acoustic surveys are routinely used to assess fish abundance. To ensure accurate population estimates, the characteristics of echoes from constituent species must be quantified. Kirchhoff-ray mode (KRM) backscatter models were used to quantify acoustic characteristics of Bering Sea and Gulf of Alaska pelagic fish species: capelin (Mallotus villosus), Pacific herring (Clupea pallasii), walleye pollock (Theragra chalcogramma), Atka mackerel (Pleurogrammus monopterygius), and eulachon (Thaleichthys pacificus). Atka mackerel and eulachon do not have swimbladders. Acoustic backscatter was estimated as a function of insonifying frequency, fish length, and body orientation relative to the incident wave front. Backscatter intensity and variance estimates were compared to examine the potential to discriminate among species. Based on relative intensity differences, species could be separated in two major groups: fish with gas-filled swimbladders and fish without swimbladders. The effects of length and tilt angle on echo intensity depended on frequency. Variability in target strength (TS) resulting from morphometric differences was high for species without swimbladders. Based on our model predictions, a series of TS to length equations were developed for each species at the common frequencies used by fisheries acousticians.

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Section: Discussionmentioning

confidence: 99%

Acoustic characteristics of forage fish species in the Gulf of Alaska and Bering Sea based on Kirchhoff-approximation models

Gauthier¹,

Horne²

2004

Can. J. Fish. Aquat. Sci.

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“…liquid to gas) [31] . Fishes without swimbladders have relatively weak acoustic signals, as fish flesh has an acoustic impedance only 10% greater than water [29] . Many fish species have lost their swimbladders, presumably as an adaptation to their benthic or deep-sea lifestyle [32] .…”

Section: Introductionmentioning

confidence: 99%

The Ecological Conditions That Favor Tool Use and Innovation in Wild Bottlenose Dolphins (Tursiops sp.)

Patterson

Mann

2011

PLoS ONE

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Dolphins are well known for their exquisite echolocation abilities, which enable them to detect and discriminate prey species and even locate buried prey. While these skills are widely used during foraging, some dolphins use tools to locate and extract prey. In the only known case of tool use in free-ranging cetaceans, a subset of bottlenose dolphins (Tursiops sp.) in Shark Bay, Western Australia habitually employs marine basket sponge tools to locate and ferret prey from the seafloor. While it is clear that sponges protect dolphins' rostra while searching for prey, it is still not known why dolphins probe the substrate at all instead of merely echolocating for buried prey as documented at other sites. By ‘sponge foraging’ ourselves, we show that these dolphins target prey that both lack swimbladders and burrow in a rubble-littered substrate. Delphinid echolocation and vision are critical for hunting but less effective on such prey. Consequently, if dolphins are to access this burrowing, swimbladderless prey, they must probe the seafloor and in turn benefit from using protective sponges. We suggest that these tools have allowed sponge foraging dolphins to exploit an empty niche inaccessible to their non-tool-using counterparts. Our study identifies the underlying ecological basis of dolphin tool use and strengthens our understanding of the conditions that favor tool use and innovation in the wild.

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“…Swimbladder first inflation ranges from 3 to 15 days depending on species and temperature (Doroshev et al , 1981; Bailey & Doroshev, 1995). Haslett (1962) and Foote (1980 a ) have shown that the swimbladder contributes a minimum of 90% to the backscatter from swimbladdered fishes, which includes O. mykiss . To illustrate the acoustic contribution of the swimbladder using the example fish at a L T of 333 mm, TS values were reduced by 9·3 dB re 1 μPa at 38 kHz and 21·7 dB re 1 μPa at 120 kHz when the swimbladder was removed from model calculations.…”

Section: Discussionmentioning

confidence: 99%

“…target strengths) of swimbladdered fishes. Swimbladders are especially important since they reflect a minimum of 90% of the acoustic energy from individual fishes (Haslett, 1962; Foote, 1980 a ) and vary in shape and size within (Foote, 1985) and among (Whitehead & Blaxter, 1964) fish species. Conversion of reflected energy ( i.e.…”

Section: Introductionmentioning

confidence: 99%

Acoustic ontogeny of a teleost

Horne

2008

Journal of Fish Biology

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The influence of growth on the intensity and variability of acoustic echoes from individuals and groups of a teleosts was quantified using Donaldson trout (rainbow-steelhead hybrid) Oncorhynchus mykiss. Fish growth was linear in total length (L T ) and quadratic in mass. Dorsal swimbladder area increased exponentially with L T . Allometric growth ratio (i.e. k) values of swimbladder length linearly increased with L T . Average swimbladder volumes occupied 3-6% of fish body volume and increased exponentially with L T . The aspect angle that resulted in the maximum average acoustic intensity from the group shifted from 80 to 86°through the experimental period. Mean echo intensities increased at both 38 and 120 kHz as mean L T increased. Predicted echo intensities at 38 kHz exceeded that at 120 kHz at L T <150 mm but were less than that predicted at 120 kHz at L T >280 mm. Generalized additive mixed models using L T , swimbladder angles and lateral elongation ratios of fish bodies were better predictors of echo intensities than L T alone.

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The Back-scattering of Acoustic Waves in Water by an Obstacle II: Determination of the Reflectivities of Solids using Small Specimens

Cited by 18 publications

References 5 publications

Acoustic characteristics of forage fish species in the Gulf of Alaska and Bering Sea based on Kirchhoff-approximation models

Acoustic characteristics of forage fish species in the Gulf of Alaska and Bering Sea based on Kirchhoff-approximation models

The Ecological Conditions That Favor Tool Use and Innovation in Wild Bottlenose Dolphins (Tursiops sp.)

Acoustic ontogeny of a teleost

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