Upload
abiola
View
82
Download
0
Embed Size (px)
DESCRIPTION
2003 Acoustical Society of America Pages: 2757–2766. Kelly J. Benoit-Bird and Whitlow W. L. Au Reporter : 曾綺停. Acoustic backscattering by Hawaiian lutjanid snappers 夏威夷鯛 科聲波探測之研究 I. Target strength and swimbladder characteristics 單體標物反射強度與泳鰾特性. Introduction. - PowerPoint PPT Presentation
Citation preview
ACOUSTIC BACKSCATTERING BY HAWAIIAN LUTJANID SNAPPERS 夏威夷鯛科聲波探測之研究I. TARGET STRENGTH AND SWIMBLADDER CHARACTERISTICS 單體標物反射強度與泳鰾特性
Kelly J. Benoit-Bird and Whitlow W. L. Au
Reporter :曾綺停
2003 Acoustical Society of America Pages: 2757–2766
Introduction
The most commercially important bottomfish, are the primary species of concern in Hawaiian.
About these deepwater fish and their habitat is very little known.
Need for detailed acoustic backscattering data for targeted species.
Red snapper
Long-tailed red snapper
Pink snapper
Brighma’s snapper
Von Siebold’s snapper
Blue-striped snapper
Objective
The first objective was to obtain controlled measurements of acoustic backscatter strength from all aspects of these fish, particularly the two depleted species and the pink snapper, which is the most commercially valuable species.
The second was to measure the shape, size, and orientation of the swimbladders of the same fish.
Objective three was to assess how acoustic backscattering strength was related to the swimbladder measures and other physiological characters such as length, biovolume, and wet weight.
本文精華資料蒐集採樣泳鰾與 TS之間理論關係
聲學背景分析方法 TS實驗流程及技術
結果分析
Methods
anestsetizedacclimated
transported
Kept alive
captured
文字
A. BackscatterFrequency range of 60 100 150 200 kHz
B. SwimbladdersPreserving
swimbladders to slit the fish ventral side, and inject Plaster of Paris
X rays after frozen, maeasured dorsal and lateral aspect
measured length, total length, displacement volume, and wet weight
over-anesthetization using 2 mL of 2-phenoxy-ethanol
per 10L of seawater
Red snapper
Long-tailed red snapper
Pink snapper
Brighma’s snapper
Von Siebold’s snapper
Blue-striped snapper
C. Data analysis
First, the maximum measured TS was compared to the TS of the fish predicted by modeling the swimbladder as a prolate spheroid.The second model predictstarget strength of the fish by modeling the swimbladder as a sphere with a volume equivalent to that measured from the plaster cast of the swimbladder.
(Furusawa,1988)
(Urick,1983)
Results1.Swimbladders
Red snapper
Long-tailed red snapper
Pink snapper
Brighma’s snapper
Von Siebold’s snapper
Blue-striped snapper
Results2.Target strength
The angle at which the maximum dorsal-aspect target strength was measured had a nearly one-to-one relationship with the angle of the swimbladder relative to the dorsal aspect of the fish, regardless of species
• Pink snapperTS=20.6*㏒ (FSL)-55.1, r2=0.85• Red snapperTS=13.7*㏒ (FSL)-46.4, r2=0.54• Longtailed red snapperTS=12.6*㏒ (FSL)-42.9, r2=0.80
• Pink snapperTS=26.2*㏒ (FSL)-63.5, r2=0.85• Red snapperTS=47.2*㏒ (FSL)-98.3, r2=0.81• Longtailed red snapperTS=28.9*㏒ (FSL)-68.8, r2=0.81
.
Variancevalues increased from 13 to 49 dB with increasing frequency 0.1 to 11 dB
Red snapper
Long-tailed red snapper
Pink snapper
Red snapper
Long-tailed red snapper
Pink snapper
Red snapper
Long-tailed red snapper
Pink snapper
lower
Red snapper
Long-tailed red snapper
Pink snapper
Results3.ModelsAbout both the dorsal and lateral aspects of the fish are the most important for utilizing these measures in a field study.The target strength over this range of angles had a range of 8 to 12 dB in the tilt plane, 2.5 to 7 dB in the roll plane, and 4 to 6 dB in the lateral plane.
Red snapper wet weight (g)=22983*sigma(m2)-18.39 (r2=0.82 P<0.05)Long-tailed red snapper wet weight(g)=24631*sigma(m2)-527.55 (r2=0.71 P<0.05)red snapper wet weight(g)=12665*sigma(m2)-122.91 (r2=0.77 P<0.05)
Discussion
The differences in volume between fish aregreater within each genus than between them.
Target strengths, both lateral and dorsal,of all three target species were correlated with standardlength.
Variance in target strength within individuals aboutthe lateral axis was also high.
This could permit a conversion ofacoustic scattering to snapper species biomass, even if specificspecies identification were not possible.