scholarly journals Acoustic data collected during and between bottom trawl stations: consistency and common trends

2007 ◽  
Vol 64 (1) ◽  
pp. 166-180 ◽  
Author(s):  
Nicolas Bez ◽  
David Reid ◽  
Suzanna Neville ◽  
Yves Vérin ◽  
Vidar Hjellvik ◽  
...  
Keyword(s):  
Bottom Trawl ◽  
Vertical Profiles ◽  
Spatial Structures ◽  
Acoustic Measurements ◽  
Acoustic Data ◽  
Global Indices ◽  
Abundance Estimates ◽  
Before And After ◽  
Systematic Perturbation ◽  
Trawl Surveys

Acoustic data are often collected during bottom trawl surveys. Their use can potentially improve the precision and accuracy of fish abundance estimates if acoustic data collected between trawl stations are consistent with those collected during trawling operations. This question is addressed here through the analysis of 20 bottom trawl surveys (three survey areas and five different survey series) with coincident acoustic measurements during and between trawl stations. Firstly, on-station and underway acoustic data were compared using statistics computed globally over each survey (average vertical profiles, global indices of collocations, and spatial structures) for various combinations of depth layers. Secondly, we focussed on underway acoustic data recorded in the vicinity of stations, distinguishing between data recorded before and after the tows. On-station and underway acoustic data were highly consistent, and no systematic perturbation of the acoustic sign due to the presence of the gear a few hundred metres behind the vessel was observed.

Calculation of untrawlable areas within the boundaries of a bottom trawl survey

2003 ◽  
Vol 60 (6) ◽  
pp. 657-669 ◽  
Author(s):  
Mark Zimmermann
Keyword(s):  
Relative Abundance ◽  
Species Group ◽  
Bottom Trawl ◽  
Trawl Survey ◽  
Gis Analysis ◽  
Target Species ◽  
Abundance Estimates ◽  
Original Target ◽  
Catch Rates ◽  
Trawl Surveys

A geographic information system (GIS) analysis of 5039 bottom trawl events from U.S. west coast bottom trawl surveys (1977–1998) estimated that the survey area was about 77% trawlable but five of the 30 strata were less than 50% trawlable. Untrawlable areas, by definition, cannot be surveyed with the bottom trawl; however, there has never been a means of identifying and excluding these areas from relative abundance estimates, which are calculated only from hauls completed in the trawlable portions of each stratum. Unknown amounts of untrawlable habitat are a problem for relative abundance estimation in many bottom trawl surveys. This manuscript describes one method of using the bottom trawling events of a survey, such as ripped-up hauls and abandoned stations, to calculate the amount of area that is untrawlable. A comparison of catch rates between undamaged tows and a limited number of damaged tows, which are normally discarded as faulty samples, showed that Sebastes catch rates were generally higher in damaged tows. Thus untrawlable areas may have substantial importance on relative abundance estimates of Sebastes, the original target species group for this survey.

scholarly journals Day–night differences in Cunene horse mackerel (Trachurus trecae) acoustic relative densities off Angola

2010 ◽  
Vol 67 (5) ◽  
pp. 1004-1009 ◽  
Author(s):  
Filomena Vaz Velho ◽  
Pedro Barros ◽  
Bjørn Erik Axelsen
Keyword(s):  
Diurnal Variation ◽  
Pelagic Zone ◽  
Horse Mackerel ◽  
Acoustic Measurements ◽  
Night Time ◽  
Fish School ◽  
Acoustic Data ◽  
Abundance Estimates ◽  
Vertical Distributions ◽  
Horizontal And Vertical Distributions

Abstract Vaz Velho, F., Barros, P., and Axelsen, B. E. 2010. Day–night differences in Cunene horse mackerel (Trachurus trecae) acoustic relative densities off Angola. – ICES Journal of Marine Science, 67: 1004–1009. The assessment and the management of the Cunene horse mackerel in Angola rely heavily on abundance estimates from hydroacoustic surveys. Acoustic data collected from 1994 to 1999 were analysed to quantify diurnal variation in relative acoustic densities at 38 kHz. The nautical-area scattering coefficient (sA, m2 nautical mile−2) was characterized by clear day–night differences: sA values recorded during the day were significantly higher (mean sA: 135 m2 nautical mile−2) than the corresponding night-time values (mean sA 83 m2 nautical mile−2). This pattern is associated with differences in behaviour and horizontal and vertical distributions between day and night: by day, the fish school near the seabed, and by night, they move into the pelagic zone and disperse into widespread scattering layers. More than 40% of the total backscatter by day originated from the bottom 10 m, but at night this proportion decreased to <10%. The findings demonstrate considerable influences of behaviour and aggregation dynamics on acoustic measurements. Possible implications for the estimates of acoustic abundance are discussed in the light of the differences.

Combining bottom trawl and acoustic data to model acoustic dead zone correction and bottom trawl efficiency parameters for semipelagic species

2013 ◽  
Vol 70 (2) ◽  
pp. 208-219 ◽  
Author(s):  
Stan Kotwicki ◽  
Alex De Robertis ◽  
James N. Ianelli ◽  
André E. Punt ◽  
John K. Horne
Keyword(s):  
Dead Zone ◽  
Light Level ◽  
Walleye Pollock ◽  
Modeling Method ◽  
Bottom Trawl ◽  
Acoustic Measurements ◽  
Habitat Features ◽  
Acoustic Data ◽  
Eastern Bering Sea ◽  
Pelagic Habitat

We present a modeling method that combines acoustic and bottom trawl abundance measurements and habitat data to estimate acoustic dead zone (ADZ) correction and bottom trawl efficiency parameters. Bottom trawl and acoustic measurements of walleye pollock (Theragra chalcogramma) abundance and available habitat data from the eastern Bering Sea are used to illustrate this method. Our results show that predictions of fish abundance in the ADZ can be improved by incorporating bottom habitat features such as depth and sediment particle size, as well as pelagic habitat features such as water temperature, light level, and current velocity. We also obtain predictions for trawl efficiency parameters such as effective fishing height, density-dependent trawl efficiency, and catchability ratio between trawl and acoustic data by modeling bottom trawl catches as a function of acoustic measurements and the environmentally dependent ADZ correction. We conclude that catchability of walleye pollock for either survey is spatially and temporarily variable. Our modeling method can be applied to other semipelagic species to obtain estimates of ADZ correction and bottom trawl efficiency parameters.

Improving area swept estimates from bottom trawl surveys

2011 ◽  
Vol 110 (1) ◽  
pp. 198-206 ◽  
Author(s):  
Stan Kotwicki ◽  
Michael H. Martin ◽  
Edward A. Laman
Keyword(s):  
Bottom Trawl ◽  
Trawl Surveys

Vertical Distribution of Fish Biomass in Lake Superior: Implications for Day Bottom Trawl Surveys

2007 ◽  
Vol 27 (3) ◽  
pp. 735-749 ◽  
Author(s):  
Jason D. Stockwell ◽  
Daniel L. Yule ◽  
Thomas R. Hrabik ◽  
Jean V. Adams ◽  
Owen T. Gorman ◽  
...  
Keyword(s):  
Vertical Distribution ◽  
Lake Superior ◽  
Bottom Trawl ◽  
Fish Biomass ◽  
Distribution Of Fish ◽  
Trawl Surveys

Do Flexible Silicone Tubes Immersed in Water Combined With Vocalise Improve the Immediate Effect on Voice?

2021 ◽  
pp. 1-28
Author(s):  
Nathália Suellen Valeriano Cardoso ◽  
Jonia Alves Lucena ◽  
Zulina Souza de Lira ◽  
Silvio José de Vasconcelos ◽  
Leonardo Wanderley Lopes ◽  
...  
Keyword(s):  
Acoustic Measurements ◽  
Post Intervention ◽  
Silicone Tube ◽  
Maximum Phonation Time ◽  
Range Profile ◽  
Before And After ◽  
Quasi Experimental ◽  
Vocal Effort ◽  
Cepstral Peak Prominence ◽  
Voice Range

Purpose: This study aimed to analyze the immediate effect on a singer's voice of a flexible silicone tube immersed in water combined with ascending and descending vocalise scales compared with ascending and descending vocalise scales alone. Method: A pre- and post-intervention quasi-experimental study was conducted. Thirty adult singers between 18 and 45 years old with no laryngeal disorders performed the two techniques for 3 min each on different days. Acoustic measurements of frequency, jitter, shimmer, glottal-to-noise excitation ratio, noise, smoothed cepstral peak prominence (CPPS), maximum phonation time (MPT), voice range profile, and self-perceived vocal effort (Borg Category Ratio 10-BR Scale adapted for vocal effort) were assessed before and after performing the techniques. Results: The results indicated an increase in singers' CPPS and MPT values and a decrease in shimmer and noise when performing with a flexible silicone tube immersed in water combined with vocalise. The singers reported a perception of decreased vocal effort after both methods. However, the diminished perceived vocal effort became more pronounced with the tube phonation technique combined with vocalise. Conclusions: Phonation in tubes combined with vocalise improved the vocal acoustic parameters (including cepstral measurements), increased MPT, and diminished perceived vocal effort. Although using vocalise alone diminished perceived vocal effort, this decrease was more pronounced in the tube phonation technique combined with vocalise.

Sign in / Sign up

Export Citation Format

Share Document