scholarly journals A revised target strength–length estimate for blue whiting (Micromesistius poutassou): implications for biomass estimates

2011 ◽  
Vol 68 (10) ◽  
pp. 2222-2228 ◽  
Author(s):  
Geir Pedersen ◽  
Olav Rune Godø ◽  
Egil Ona ◽  
Gavin J. Macaulay
Keyword(s):  
Target Strength ◽  
Similar Species ◽  
The West ◽  
Norwegian Sea ◽  
Blue Whiting ◽  
Length Relationship ◽  
Abundance Estimates ◽  
Acoustic Target ◽  
Length Estimate ◽  
The Relationship

Abstract Pedersen, G., Godø, O. R., Ona, E., and Macaulay, G. J. 2011. A revised target strength–length estimate for blue whiting (Micromesistius poutassou): implications for biomass estimates. – ICES Journal of Marine Science, 68: 2222–2228. Acoustic abundance estimates of blue whiting have generally been higher than estimates based on catch data. One explanation has been that the relationship between acoustic target strength (TS) and length is too low and hence overestimates the number of fish. Measurements of TS were conducted during surveys of blue whiting in March/April 2003–2007 to the west of the British Isles from several different measurement platforms, and also during August 2005 in the Norwegian Sea. Results from these experiments confirm the view that the existing TS–length relationship is too low. A new TS–length relationship is proposed that is ∼5 dB higher. Blue whiting TS is considerably higher than observed and modelled for a similar species, southern blue whiting (Micromesistius australis).

scholarly journals In situ target strength estimates of optically verified southern blue whiting (Micromesistius australis)

2012 ◽  
Vol 70 (2) ◽  
pp. 431-439 ◽  
Author(s):  
Richard L. O'Driscoll ◽  
Johannes Oeffner ◽  
Adam J. Dunford
Keyword(s):  
New Zealand ◽  
Confidence Interval ◽  
Fork Length ◽  
Target Strength ◽  
Blue Whiting ◽  
Acoustic Target ◽  
The Mean ◽  
The Relationship ◽  
Immature Fish

Abstract O'Driscoll, R. L., Oeffner, J., and Dunford, A. J. 2013. In situ target strength estimates of optically verified southern blue whiting (Micromesistius australis) – ICES Journal of Marine Science, 70: 431–439. Estimates of the acoustic target strength (TS) of southern blue whiting (Micromesistius australis) at 38 kHz were obtained using an autonomous acoustic–optical system (AOS) mounted on a demersal trawl. Data were collected from aggregations of spawning adult [mean fork length (FL) 34.4 cm] and immature (mean FL 24.6 cm) southern blue whiting south of New Zealand. Mean TS was estimated from 162 tracks containing 695 echoes from targets identified from video as southern blue whiting. The mean TS was –37.9 dB with a 95% confidence interval (CI) of –39.7 to –36.6 dB for 21 immature fish and –34.6 dB (95% CI –35.4 to –34.0 dB) for 141 adults. A logarithmic fit through the mean TS values produced a TS–fork length (FL) relationship from optically verified targets of TS = 22.06 log10FL – 68.54. This new relationship gives TS values within 1 dB of those estimated using the relationship recently adopted by ICES for blue whiting (Micromesistius poutassou) of TS = 20 log10TL – 65.2 (where TL is total length) obtained from in situ measurements, but higher values than those estimated from the previous relationship for southern blue whiting of TS = 38 log10FL – 97, which was based on swimbladder modelling.

scholarly journals Progress in determining southern blue whiting (Micromesistius australis) target strength: results of swimbladder modelling

2006 ◽  
Vol 63 (5) ◽  
pp. 952-955 ◽  
Author(s):  
Adam J. Dunford ◽  
Gavin J. Macaulay
Keyword(s):  
Gadus Morhua ◽  
Stock Assessment ◽  
Laser Scanner ◽  
Fork Length ◽  
Sensitivity Analyses ◽  
Target Strength ◽  
Fish Length ◽  
Angle Distribution ◽  
Blue Whiting ◽  
The Relationship

Abstract Southern blue whiting target strength (TS) results from Kirchhoff modelling of swimbladder casts scanned using a hand-held 3D laser scanner are presented. The data are compared with the relationship between TS and fish length used for New Zealand stock-assessment surveys; TS = 21.8 log10(fork length) − 72.8, at 38 kHz. This relationship has its origins in the relationship used for blue whiting (Micromesistius poutassou) in the northern hemisphere, and is based on measurements on juvenile cod (Gadus morhua). The results indicate that the blue whiting relationship is not appropriate for southern blue whiting, and suggest a much steeper slope, with TS = 38 log10(fork length) − 97, at 38 kHz. Sensitivity analyses indicate that further investigations of swimbladder tilt-angle distribution and swimbladder volume are unlikely to provide evidence to support the use of the blue whiting relationship for southern blue whiting.

scholarly journals Extraction and comparison of acoustic backscatter from a calibrated multi- and single-beam sonar

2003 ◽  
Vol 60 (3) ◽  
pp. 669-677 ◽  
Author(s):  
Gary D Melvin ◽  
Norman A Cochrane ◽  
Yanchao Li
Keyword(s):  
Acoustic Properties ◽  
Target Strength ◽  
Acoustic Backscatter ◽  
Biomass Estimation ◽  
Single Beam ◽  
Acoustic Data ◽  
Powerful Analytical Tool ◽  
Acoustic Target ◽  
Element Array ◽  
The Relationship

Abstract Multi-beam sonar is potentially a powerful analytical tool for investigating the acoustic properties and behaviour of fish in relation to quantitative fisheries research. The SIMRAD SM2000 is a 200 kHz multi-beam sonar employing an 80-element array to transmit and synthesize, electronically, 128 receive beams (20°×2.2°) over a 180° arc simultaneously. Once calibrated, such systems enable the extraction of acoustic target strength and volume backscattering from an extended 3D ocean volume. We present an overview of the theoretical framework for the calibration of a multi-beam sonar, and then compare the acoustic backscatter from a calibrated single-beam 50 kHz echosounder with selected beams from a sphere-calibrated multi-beam sonar. Both systems recorded acoustic data from Atlantic herring contained within a weir, as the fish passed beneath the transducers. Specifically, we examine the relationship between the area-backscattering strength (Sa) from the single-beam system with the nadir beam (beam 63) of the SM2000 sonar. In addition, data are presented on the observed variability in Sa with target aspect for off-vertical angles from 15° to 60° in 15° intervals. Non-standard synthesized SM2000 beam widths are explored for both calibration and field datasets. The implications for biomass estimation are also discussed.

scholarly journals In situ target strength of the Baltic Sea herring and sprat

2004 ◽  
Vol 61 (3) ◽  
pp. 378-382 ◽  
Author(s):  
Tomas Didrikas ◽  
Sture Hansson
Keyword(s):  
Baltic Sea ◽  
Clupea Harengus ◽  
Target Strength ◽  
Fish Length ◽  
The North ◽  
Length Relationship ◽  
Stock Biomass ◽  
Acoustic Target ◽  
The North Sea ◽  
The Baltic

Abstract Using single- and split-beam hydroacoustic equipment (70 and 38 kHz), and gillnet and trawl catches, we derived the relationship TS = 25.5 log10 L − 73.6 (r2=0.95) between acoustic target strength (TS) and fish length (L, cm) for Baltic Sea herring (Clupea harengus membras L.) and sprat (Sprattus sprattus balticus (Schneider)). Fixing the slope to 20, which is a standard practice in hydroacoustics, gave TS = 20 log10 L − 67.8 (r2=0.91). Normally, the fisheries agencies around the Baltic use a TS–length relationship that is based mainly on data from the North Sea and the intercept-value in this equation is 3.4 dB lower than that reported in this paper. This difference corresponds to an approximately twofold difference in assessed stock biomass.

Implications of a new acoustic target strength for abundance estimates of Antarctic krill

Nature ◽  
1990 ◽  
Vol 345 (6273) ◽  
pp. 338-340 ◽  
Author(s):  
Inigo Everson ◽  
Jonathan L. Watkins ◽  
Douglas G. Bone ◽  
Kenneth G. Foote
Keyword(s):  
Antarctic Krill ◽  
Target Strength ◽  
Abundance Estimates ◽  
Acoustic Target

Improvements in estimating an acoustic target strength–length relationship for hoki (Macruronus novaezeladiae)

2015 ◽  
Vol 162 ◽  
pp. 12-19 ◽  
Author(s):  
Adam J. Dunford ◽  
Richard L. O’Driscoll ◽  
Johannes Oeffner
Keyword(s):  
Target Strength ◽  
Length Relationship ◽  
Acoustic Target

The acoustic target strength of herring (Clupea harengus L.) in the northern Baltic Sea

2005 ◽  
Vol 62 (4) ◽  
pp. 803-808 ◽  
Author(s):  
Heikki Peltonen ◽  
Helge Balk
Keyword(s):  
Baltic Sea ◽  
Clupea Harengus ◽  
Target Strength ◽  
Fish Length ◽  
The Baltic Sea ◽  
Length Relationship ◽  
Acoustic Target ◽  
The Baltic ◽  
Catch Composition ◽  
Bothnian Sea

Abstract The hydro-acoustic target strength (TS) of herring (Clupea harengus L.) was estimated from the catch composition of 19 pelagic-trawl hauls and from simultaneous recordings with a split-beam, 38 kHz echosounder. The data were collected in September 2000 during a Bothnian Sea survey in the northern Baltic Sea. The dependence of TS (in dB) on fish length (L, cm) was modelled with the equation TS = a log10 L + b. The fitted model was TS = 16.8 log10 L − 60.0. With a predefined slope of 20 the TS vs. log-fish length relationship was TS = 20 log10 L − 63.9. The analyses suggested that TS was higher in the Bothnian Sea than is assumed in most studies in the Baltic Sea. Applying the revised TS–length dependence considerably enhanced the agreement between the biomass estimates from hydroacoustics and those from a catche-at-age analysis (VPA).

Contemporary Qur'anic Studies in Iran and its Relationship with Qur'anic Studies in the West

2012 ◽  
Vol 14 (1) ◽  
pp. 45-72
Author(s):  
Morteza Karimi-Nia
Keyword(s):  
Islamic Law ◽  
Human Sciences ◽  
The West ◽  
Communications Technologies ◽  
Religious Learning ◽  
The Status ◽  
Islamic Republic Of Iran ◽  
Almost All ◽  
The Impact ◽  
The Relationship

The status of tafsīr and Qur'anic studies in the Islamic Republic of Iran has changed significantly during recent decades. The essay provides an overview of the state of Qur'anic studies in Iran today, aiming to examine the extent of the impact of studies by Western scholars on Iranian academic circles during the last three decades and the relationship between them. As in most Islamic countries, the major bulk of academic activity in Iran in this field used to be undertaken by the traditional ʿulamāʾ; however, since the beginning of the twentieth century and the establishment of universities and other academic institutions in the Islamic world, there has been increasing diversity and development. After the Islamic Revolution, many gradual changes in the structure and approach of centres of religious learning and universities have occurred. Contemporary advancements in modern sciences and communications technologies have gradually brought the institutions engaged in the study of human sciences to confront the new context. As a result, the traditional Shīʿī centres of learning, which until 50 years ago devoted themselves exclusively to the study of Islamic law and jurisprudence, today pay attention to the teaching of foreign languages, Qur'anic sciences and exegesis, including Western studies about the Qur'an, to a certain extent, and recognise the importance of almost all of the human sciences of the West.

JOHN LOUIS ESPOSITO TENTANG DIALOG PERADABAN ISLAM-BARAT

1970 ◽  
Vol 7 (1) ◽  
Author(s):  
Moh. Salman Hamdani
Keyword(s):  
Common Ground ◽  
Entry Point ◽  
The West ◽  
Strong Bond ◽  
Historical Fact ◽  
Muslim Intellectuals ◽  
Abrahamic Religions ◽  
Cultural Dialogue ◽  
The Relationship

This paper aims to provide explanation about John Louis Esposito’s insights on therelationship between Islam and The West. The relationship is a fluctuative one, some tensionsand even open conflict may occur. Some events become the entry point to the relationship, forinstance, the crusades that is not only happened physically but also, through this war, the meetingbetween Islam and The West establishes inter cultural dialogue among them.John Louis Esposito’s views on the relationship between Islam and The West ispositioned in view of some Muslim intellectuals and orientalists to emphasize its originality. Theintellectual positions do not put it on pros or cons side in the context of the relationship betweenIslam and The West.Historically, the relationship between Islam and The West actually has a theologicallystrong bond that there is common ground and similarities between Islam and The West. Islamand The west are inherited with Jewish and Christian traditions. Islam like Christianity andJudaism are religions ‘of the sky’ that are allied in Abrahamic religions. Therefore, according toJohn L. Esposito, based on historical fact, there were a real strong bond between Islam and theWest and it started centuries ago .

Rola Avarského Kaganátu Pri Vzniku Slovenčiny

2018 ◽  
Vol 69 (2) ◽  
pp. 199-236
Author(s):  
Martin Braxatoris ◽  
Michal Ondrejčík
Keyword(s):  
Slavic Language ◽  
The West ◽  
The North ◽  
Danube Region ◽  
The Absolute ◽  
North Edge ◽  
The Relationship ◽  
Slovak Language

Abstract The paper proposes a basis of theory with the aim of clarifying the casual nature of the relationship between the West Slavic and non-West Slavic Proto-Slavic base of the Slovak language. The paper links the absolute chronology of the Proto-Slavic language changes to historical and archaeological information about Slavs and Avars. The theory connects the ancient West Slavic core of the Proto-Slavic base of the Slovak language with Sclaveni, and non-West Slavic core with Antes, which are connected to the later population in the middle Danube region. It presumes emergence and further expansion of the Slavic koiné, originally based on the non-West Slavic dialects, with subsequent influence on language of the western Slavic tribes settled in the north edge of the Avar Khaganate. The paper also contains a periodization of particular language changes related to the situation in the Khaganate of that time.

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