Kelly J. Benoit-Bird and Whitlow W. L. Au Reporter : 曾綺停

1. 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 lutjanidsnappers 夏威夷鯛科聲波探測之研究I. Target strength and swimbladdercharacteristics 單體標物反射強度與泳鰾特性

2. Introduction The most commercially importantbottomfish, are the primary species of concern inHawaiian. About these deepwater fish andtheir habitatisvery little known. Needfor detailed acoustic backscattering data for targeted species.

3. Red snapper Brighma’s snapper Long-tailed red snapper Von Siebold’s snapper Pink snapper Blue-striped snapper

4. Objective • The first objective was to obtain controlled measurements of acoustic backscatterstrength from all aspects of these fish, particularly the twodepleted species and the pink snapper, which is the mostcommercially valuable species. • The second was to measurethe shape, size, and orientation of the swimbladders of thesame fish. • Objective three was to assess how acoustic backscatteringstrength was related to the swimbladder measuresand other physiological characters such as length, biovolume,and wet weight.

5. 泳鰾與TS 之間 理論關係 資料蒐集 採樣 聲學背景 分析方法 TS實驗流程 及技術 本文精華 結果分析

6. Methods captured Kept alive transported acclimated anestsetized

7. 文字

8. A. Backscatter Frequency range of 60 100 150 200 kHz

9. over-anesthetization using 2 mL of 2-phenoxy-ethanol per 10L of seawater measured length, total length, displacement volume, and wet weight X rays after frozen, maeasured dorsal and lateral aspect Preserving swimbladders to slit the fish ventral side, and inject Plaster of Paris B. Swimbladders

10. Red snapper Long-tailed red snapper Pink snapper

11. Brighma’s snapper Von Siebold’s snapper Blue-striped snapper

12. First, the maximum measuredTSwas compared to theTSof the fish predicted bymodeling the swimbladder as aprolate spheroid. The second model predicts target strength of the fish by modeling the swimbladder as asphere with a volume equivalent to that measured from theplaster cast of the swimbladder. (Furusawa,1988) (Urick,1983) C. Data analysis

13. Results1.Swimbladders Red snapper Long-tailed red snapper Pink snapper

14. Brighma’s snapper Von Siebold’s snapper Blue-striped snapper

16. Results2.Target strength The angle at which the maximum dorsal-aspect targetstrength was measured had anearly one-to-onerelationshipwith the angle of theswimbladder relative to the dorsal aspect of the fish, regardlessof species

17. Pink snapper TS=20.6*㏒(FSL)-55.1, r2=0.85 • Red snapper TS=13.7*㏒(FSL)-46.4, r2=0.54 • Longtailed red snapper TS=12.6*㏒(FSL)-42.9, r2=0.80 • Pink snapper TS=26.2*㏒(FSL)-63.5, r2=0.85 • Red snapper TS=47.2*㏒(FSL)-98.3, r2=0.81 • Longtailed red snapper TS=28.9*㏒(FSL)-68.8, r2=0.81

18. . Variance values increased from 13 to 49 dB with increasing frequency 0.1 to 11 dB

19. Red snapper Long-tailed red snapper Pink snapper

20. Red snapper Long-tailed red snapper Pink snapper

21. Red snapper Long-tailed red snapper lower Pink snapper

22. Red snapper Long-tailed red snapper Pink snapper

23. Results3.Models About 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)

24. Discussion This could permit a conversion of acoustic scattering to snapper species biomass, even if specific species identification were not possible. Target strengths, both lateral and dorsal, of all three target species were correlated with standard length. Variance in target strength within individuals about the lateral axis was also high. The differences in volume between fish are greater within each genus than between them.