Ex situ target strength measurements of Pacific herring and Pacific sand lance

Gary Thomas, Jay Kirsch, Richard E. Thorne

Research output: Contribution to journalArticle

28 Citations (Scopus)

Abstract

Near-dorsal aspect target strengths (TS) of individual live juvenile and adult Pacific herring Clupea pallasi and juvenile Pacific sand lance Ammodytes hexapterus were measured ex situ with 120-kHz dual-beam acoustics. An experimental frame was designed to support a transducer, fish cage, standard calibration target, and two video cameras. Pacific herring were measured at a variety of depths while they swam freely in an acoustically transparent cylinder that was secured 3 m below the transducer. Pacific sand lance were measured while tethered at a 4-m depth. We found that both depth and season affected the target strength of Pacific herring. The TS of individual Pacific herring declined as they were lowered in the water column. The decline was in accord with that expected from the effects of Boyle's Law on the swim bladder volume. This impact of depth may explain the apparent discrepancy in published target strength algorithms for Atlantic herring C. harengus and Pacific herring. The depth distribution of Atlantic herring is typically deeper. The results suggest that the depth of measurement needs to be considered in both target strength measurements and acoustic surveys of herring. We also found higher target strengths of Pacific herring during spring than in fall. Larger swim bladder volumes may be associated with spent fish or reduced lipid content during spring. The measurements on the juvenile Pacific sand lance, which lack swim bladders, yielded a much lower target strength than Pacific herring of equivalent size. However, the observed values were appreciably higher than the TS algorithm published for sand lance Ammodytes spp. in the Atlantic Ocean.

Original languageEnglish
Pages (from-to)1136-1145
Number of pages10
JournalNorth American Journal of Fisheries Management
Volume22
Issue number4
DOIs
StatePublished - Nov 1 2002
Externally publishedYes

Fingerprint

target strength
sand
swim bladder
Clupea harengus
transducers (equipment)
transducer
acoustics
Ammodytidae
fish cages
Clupea
Ammodytes
video cameras
acoustic survey
herring
Ammodytes hexapterus
Clupea pallasii pallasii
Atlantic Ocean
fish
calibration
vertical distribution

ASJC Scopus subject areas

  • Aquatic Science

Cite this

Ex situ target strength measurements of Pacific herring and Pacific sand lance. / Thomas, Gary; Kirsch, Jay; Thorne, Richard E.

In: North American Journal of Fisheries Management, Vol. 22, No. 4, 01.11.2002, p. 1136-1145.

Research output: Contribution to journalArticle

@article{57b775acde104d40b6a95ecf34b0617a,
title = "Ex situ target strength measurements of Pacific herring and Pacific sand lance",
abstract = "Near-dorsal aspect target strengths (TS) of individual live juvenile and adult Pacific herring Clupea pallasi and juvenile Pacific sand lance Ammodytes hexapterus were measured ex situ with 120-kHz dual-beam acoustics. An experimental frame was designed to support a transducer, fish cage, standard calibration target, and two video cameras. Pacific herring were measured at a variety of depths while they swam freely in an acoustically transparent cylinder that was secured 3 m below the transducer. Pacific sand lance were measured while tethered at a 4-m depth. We found that both depth and season affected the target strength of Pacific herring. The TS of individual Pacific herring declined as they were lowered in the water column. The decline was in accord with that expected from the effects of Boyle's Law on the swim bladder volume. This impact of depth may explain the apparent discrepancy in published target strength algorithms for Atlantic herring C. harengus and Pacific herring. The depth distribution of Atlantic herring is typically deeper. The results suggest that the depth of measurement needs to be considered in both target strength measurements and acoustic surveys of herring. We also found higher target strengths of Pacific herring during spring than in fall. Larger swim bladder volumes may be associated with spent fish or reduced lipid content during spring. The measurements on the juvenile Pacific sand lance, which lack swim bladders, yielded a much lower target strength than Pacific herring of equivalent size. However, the observed values were appreciably higher than the TS algorithm published for sand lance Ammodytes spp. in the Atlantic Ocean.",
author = "Gary Thomas and Jay Kirsch and Thorne, {Richard E.}",
year = "2002",
month = "11",
day = "1",
doi = "10.1577/1548-8675(2002)022<1136:ESTSMO>2.0.CO;2",
language = "English",
volume = "22",
pages = "1136--1145",
journal = "North American Journal of Fisheries Management",
issn = "0275-5947",
publisher = "American Fisheries Society",
number = "4",

}

TY - JOUR

T1 - Ex situ target strength measurements of Pacific herring and Pacific sand lance

AU - Thomas, Gary

AU - Kirsch, Jay

AU - Thorne, Richard E.

PY - 2002/11/1

Y1 - 2002/11/1

N2 - Near-dorsal aspect target strengths (TS) of individual live juvenile and adult Pacific herring Clupea pallasi and juvenile Pacific sand lance Ammodytes hexapterus were measured ex situ with 120-kHz dual-beam acoustics. An experimental frame was designed to support a transducer, fish cage, standard calibration target, and two video cameras. Pacific herring were measured at a variety of depths while they swam freely in an acoustically transparent cylinder that was secured 3 m below the transducer. Pacific sand lance were measured while tethered at a 4-m depth. We found that both depth and season affected the target strength of Pacific herring. The TS of individual Pacific herring declined as they were lowered in the water column. The decline was in accord with that expected from the effects of Boyle's Law on the swim bladder volume. This impact of depth may explain the apparent discrepancy in published target strength algorithms for Atlantic herring C. harengus and Pacific herring. The depth distribution of Atlantic herring is typically deeper. The results suggest that the depth of measurement needs to be considered in both target strength measurements and acoustic surveys of herring. We also found higher target strengths of Pacific herring during spring than in fall. Larger swim bladder volumes may be associated with spent fish or reduced lipid content during spring. The measurements on the juvenile Pacific sand lance, which lack swim bladders, yielded a much lower target strength than Pacific herring of equivalent size. However, the observed values were appreciably higher than the TS algorithm published for sand lance Ammodytes spp. in the Atlantic Ocean.

AB - Near-dorsal aspect target strengths (TS) of individual live juvenile and adult Pacific herring Clupea pallasi and juvenile Pacific sand lance Ammodytes hexapterus were measured ex situ with 120-kHz dual-beam acoustics. An experimental frame was designed to support a transducer, fish cage, standard calibration target, and two video cameras. Pacific herring were measured at a variety of depths while they swam freely in an acoustically transparent cylinder that was secured 3 m below the transducer. Pacific sand lance were measured while tethered at a 4-m depth. We found that both depth and season affected the target strength of Pacific herring. The TS of individual Pacific herring declined as they were lowered in the water column. The decline was in accord with that expected from the effects of Boyle's Law on the swim bladder volume. This impact of depth may explain the apparent discrepancy in published target strength algorithms for Atlantic herring C. harengus and Pacific herring. The depth distribution of Atlantic herring is typically deeper. The results suggest that the depth of measurement needs to be considered in both target strength measurements and acoustic surveys of herring. We also found higher target strengths of Pacific herring during spring than in fall. Larger swim bladder volumes may be associated with spent fish or reduced lipid content during spring. The measurements on the juvenile Pacific sand lance, which lack swim bladders, yielded a much lower target strength than Pacific herring of equivalent size. However, the observed values were appreciably higher than the TS algorithm published for sand lance Ammodytes spp. in the Atlantic Ocean.

UR - http://www.scopus.com/inward/record.url?scp=18744399823&partnerID=8YFLogxK

UR - http://www.scopus.com/inward/citedby.url?scp=18744399823&partnerID=8YFLogxK

U2 - 10.1577/1548-8675(2002)022<1136:ESTSMO>2.0.CO;2

DO - 10.1577/1548-8675(2002)022<1136:ESTSMO>2.0.CO;2

M3 - Article

AN - SCOPUS:18744399823

VL - 22

SP - 1136

EP - 1145

JO - North American Journal of Fisheries Management

JF - North American Journal of Fisheries Management

SN - 0275-5947

IS - 4

ER -