Simulation and experimental measurement of side-aspect target strength of Atlantic salmon (Salmo salar) at high frequency

Juha Lilja, Timo J. Marjomäki, Juha Jurvelius, Tuomo Rossi, Erkki Heikkola

Research output: Contribution to journalArticleScientificpeer-review

17 Citations (Scopus)

Abstract

Numerical simulations and empirical measurements of swimming Atlantic salmon (Salmo salar) were used to describe the effects of fish behavior on side-aspect target strength (TS). Simulation results were based on the numerical solution of the Helmholtz equation with the finite element method (FEM). A three-dimensional geometric model approximated the shape of the swimbladder of an Atlantic salmon. Numerical simulations were used to study the dependence of TS on the fish length, orientation, and swimming behavior. The results showed strong variation in TS, both when the side-aspect angle was changed and when the swimbladder was bent to the direction of the sonar beam. A total of 11 swimming adult Atlantic salmon 62–107 cm long were measured with a horizontally aimed echosounder (200 kHz) and video camera, and the experimental results were compared with the corresponding simulation results. The linear regression between mean TS and the logarithm of fish length (L, cm) was TS = 24.4log10(L) – 72.9 dB. The strong variability of TS owing to the orientation and bending of the fish and large L/λ ratios reduces the usefulness of TS alone for fish size estimation or species discrimination.
Original languageEnglish
Pages (from-to)2227 - 2236
Number of pages10
JournalCanadian Journal of Fisheries and Aquatic Sciences
Volume61
Issue number11
DOIs
Publication statusPublished - 2004
MoE publication typeA1 Journal article-refereed

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target strength
Salmo salar
swim bladder
fish
simulation
fish behavior
video cameras
orientation behavior
Helmholtz equation
swimming behavior
sonar
finite element method

Cite this

Lilja, Juha ; Marjomäki, Timo J. ; Jurvelius, Juha ; Rossi, Tuomo ; Heikkola, Erkki. / Simulation and experimental measurement of side-aspect target strength of Atlantic salmon (Salmo salar) at high frequency. In: Canadian Journal of Fisheries and Aquatic Sciences. 2004 ; Vol. 61, No. 11. pp. 2227 - 2236.
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title = "Simulation and experimental measurement of side-aspect target strength of Atlantic salmon (Salmo salar) at high frequency",
abstract = "Numerical simulations and empirical measurements of swimming Atlantic salmon (Salmo salar) were used to describe the effects of fish behavior on side-aspect target strength (TS). Simulation results were based on the numerical solution of the Helmholtz equation with the finite element method (FEM). A three-dimensional geometric model approximated the shape of the swimbladder of an Atlantic salmon. Numerical simulations were used to study the dependence of TS on the fish length, orientation, and swimming behavior. The results showed strong variation in TS, both when the side-aspect angle was changed and when the swimbladder was bent to the direction of the sonar beam. A total of 11 swimming adult Atlantic salmon 62–107 cm long were measured with a horizontally aimed echosounder (200 kHz) and video camera, and the experimental results were compared with the corresponding simulation results. The linear regression between mean TS and the logarithm of fish length (L, cm) was TS = 24.4log10(L) – 72.9 dB. The strong variability of TS owing to the orientation and bending of the fish and large L/λ ratios reduces the usefulness of TS alone for fish size estimation or species discrimination.",
author = "Juha Lilja and Marjom{\"a}ki, {Timo J.} and Juha Jurvelius and Tuomo Rossi and Erkki Heikkola",
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Simulation and experimental measurement of side-aspect target strength of Atlantic salmon (Salmo salar) at high frequency. / Lilja, Juha; Marjomäki, Timo J.; Jurvelius, Juha; Rossi, Tuomo; Heikkola, Erkki.

In: Canadian Journal of Fisheries and Aquatic Sciences, Vol. 61, No. 11, 2004, p. 2227 - 2236.

Research output: Contribution to journalArticleScientificpeer-review

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T1 - Simulation and experimental measurement of side-aspect target strength of Atlantic salmon (Salmo salar) at high frequency

AU - Lilja, Juha

AU - Marjomäki, Timo J.

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AU - Rossi, Tuomo

AU - Heikkola, Erkki

PY - 2004

Y1 - 2004

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AB - Numerical simulations and empirical measurements of swimming Atlantic salmon (Salmo salar) were used to describe the effects of fish behavior on side-aspect target strength (TS). Simulation results were based on the numerical solution of the Helmholtz equation with the finite element method (FEM). A three-dimensional geometric model approximated the shape of the swimbladder of an Atlantic salmon. Numerical simulations were used to study the dependence of TS on the fish length, orientation, and swimming behavior. The results showed strong variation in TS, both when the side-aspect angle was changed and when the swimbladder was bent to the direction of the sonar beam. A total of 11 swimming adult Atlantic salmon 62–107 cm long were measured with a horizontally aimed echosounder (200 kHz) and video camera, and the experimental results were compared with the corresponding simulation results. The linear regression between mean TS and the logarithm of fish length (L, cm) was TS = 24.4log10(L) – 72.9 dB. The strong variability of TS owing to the orientation and bending of the fish and large L/λ ratios reduces the usefulness of TS alone for fish size estimation or species discrimination.

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