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

Ehrenberg, John E.; Torkelson, Thomas C.

doi:10.1080/00344899028438932

Cited by 36 publications

(43 citation statements)

References 4 publications

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“…It is also unlikely that the organisms measured with the echosounder are planktonic, as the minimum target strength measured was -59 dB. The target strength of the types of the most common plankton in Hawaiian waters at 200 kHz ranges from -73 to -89 dB, even when densely clumped (Greene & Wiebe 1990, Ehrenberg & Torkelson 1996, Huse & Ona 1996, Gal et al 1999.…”

Section: Discussionmentioning

confidence: 99%

Diel horizontal migration of the Hawaiian mesopelagic boundary community observed acoustically

Benoit‐Bird¹,

Au²,

Brainard³

et al. 2001

Mar. Ecol. Prog. Ser.

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ABSTRACT:The mesopelagic boundary community off the leeward coasts of 2 Hawaiian Islands, Oahu and Hawaii, was investigated with an echosounder modified to read directly into a laptop computer. Acoustic sampling was conducted over a total distance of 12.6 km off the Waianae coast of Oahu and 46.3 km off the Kona coast of Hawaii. The density of organisms was determined using echo energy integration, and relative abundance was determined in a way analogous to catch-per-uniteffort. The vertical range of mesopelagic organisms expanded as the mesopelagic layer rose and then compressed as it descended. The vertical range of the layer off the Kona coast was larger than that off the Waianae coast, possibly because of the greater bottom depth off Kona. Near midnight, the boundary community 3 km from the shoreline was split into 2 distinct layers, one beginning approximately 25 m from the surface and one beginning approximately 90 m from the surface. The density and the relative abundance of mesopelagic organisms were consistently higher off the Waianae coast than the Kona coast. However, the density of organisms observed in both locations was high, reaching a maximum of 1800 organisms m -3 off Waianae and 700 organisms m -3 off Kona. The maximum relative abundance off Waianae neared 100%, while off Kona it never exceeded 70%. In both locations, organisms were found within 1 km of shore, in waters much shallower than their assumed daytime habitat. The temporal patterns of relative abundance and density of organisms in waters closest to the shores of each island resembled a bell curve, with a peak in relative abundance and density around midnight. In waters further from shore, the temporal patterns in relative abundance and density had a bimodal distribution, with peaks around both 21:00 and 03:00 h. These patterns in relative abundance and density are significantly affected by the distance of the sampling location from the shoreline, but not by the depth of the sampling site. The data suggest that the organisms of the mesopelagic boundary community undergo a diel horizontal migration that is reciprocal, 1.8 km in 2 h toward shore and then the same distance in approximately the same amount of time away from shore, in addition to their well-established vertical migration. The temporal patterns of the horizontal component of the migration are predictable and are conserved between days, phases of the moon, seasons, and islands.

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Section: Discussionmentioning

confidence: 99%

Diel horizontal migration of the Hawaiian mesopelagic boundary community observed acoustically

Benoit‐Bird¹,

Au²,

Brainard³

et al. 2001

Mar. Ecol. Prog. Ser.

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“…The behavior of individual jellyfish was derived from echo traces on echograms and by acoustic target tracking (TT). Split-beam echosounders can locate the position of a target in the acoustic beam (e.g., Ehrenberg and Torkelson 1996). By applying software allocating subsequent echoes to the same target (Balk and Lindem 2002), TT provides data on size (TS; target strength), three-dimensional (3-D) swimming trajectories and swimming speed of resolved individuals.…”

Section: Methodsmentioning

confidence: 99%

Diel vertical migration of individual jellyfish (Periphylla periphylla)

Kaartvedt

Klevjer

Torgersen

et al. 2007

Limnology & Oceanography

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Vertical migration of the mesopelagic jellyfish Periphylla periphylla (Scyphozoa: Coronatae) was studied by use of hull-mounted and submerged echosounders in a ,440 m deep Norwegian fjord. The research vessel was kept at a fixed position so that individual jellyfish remained in the acoustic beam for prolonged periods in the low advective environment of the deep fjord basin. The population of jellyfish was divided into different vertical modes with different migration behavior. A scattering layer (SL) of P. periphylla was located at 150-200 m during the day; it migrated coherently to the upper 50 m at night and returned to depth the next morning. A deeper SL seemed to remain below 250 m both day and night. However, focus on individuals revealed additional, asynchronous migration activity. A pulse of P. periphylla left upper layers already a few hours after sunset, and there was interchange of individuals between shallow and deep water throughout the night, including ascent of individuals from the apparent nonmigrating deepest SL. Vertical migration velocities were ,2 cm s 21 both during ascent and descent, irrespective of time. Different types of swimming behavior were reflected in the acoustic records, affecting the recorded backscatter.

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“…Split-beam echo sounders can determine both horizontal and vertical positions of a target in the acoustic beam (e.g. Ehrenberg & Torkelson 1996), and TT can be used to establish swimming trajectories through the acoustic beam by applying algorithms allocating subsequent echoes to the same target (Balk & Lindem 2002). Data on target strength (TS), a proxy for size, were also provided.…”

Section: Methodsmentioning

confidence: 99%

Behavior of individual mesopelagic fish in acoustic scattering layers of Norwegian fjords

Kaartvedt¹,

Torgersen²,

Klevjer³

et al. 2008

Mar. Ecol. Prog. Ser.

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Mesopelagic acoustic scattering layers (SLs) in 2 fjords were studied from a stationary research vessel. Diel vertical movements of SLs were assessed by hull-mounted transducers, while in situ behavior of individuals constituting the SLs was resolved by a submerged echo sounder. The study focused on SLs made up of the lightfish Maurolicus muelleri and the lanternfish Benthosema glaciale. Individual fish migrated in a pronounced stepwise manner, alternating between vertical movements and stationary phases both during ascent and descent. Mean lengths of steps varied between 2.01 and 0.40 m, and mean duration of stationary phases between 69 and 36 s for fish in different SLs. Such travel-pause behavior concords with saltatory search, where fish scan the water for prey during the stationary phases, relocate and scan a new water parcel. Little activity was recorded among individuals in deep water, apart from infrequent, short shifts in vertical distribution. This study shows that stationary submerged echo sounders can provide detailed information on in situ behavior of mesopelagic fish.

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

Cited by 36 publications

References 4 publications

Diel horizontal migration of the Hawaiian mesopelagic boundary community observed acoustically

Diel horizontal migration of the Hawaiian mesopelagic boundary community observed acoustically

Diel vertical migration of individual jellyfish (Periphylla periphylla)

Behavior of individual mesopelagic fish in acoustic scattering layers of Norwegian fjords

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