NOAA Protocols for Fisheries Acoustics Surveys and Related ...

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Center Background NEFSC The Northeast Fisheries Science Center (NEFSC) fisheries acoustics group currently has two FTE’s affiliated with the Survey Branch and one FTE affiliated with the Population Dynamic’s Branch. Two FTE’s are base funded and the other FTE is funded on a congressional budget “line-item”. The NEFSC fisheries acoustics group focuses on estimating Atlantic herring (Clupea harengus) spawning stock biomass with an annual six-week survey conducted in the fall. The Atlantic herring acoustical survey employs a systematic parallel design, with intertransect spacing set at 8 or 10 nautical miles (nmi). The transect spacing is consistent within a survey, but has changed among surveys. This is due to logistic constraints, and the fact that a definitive survey design has not been determined at this time. The extent of the survey encompasses the spawning stock biomass in the Georges Bank region. The S a values along transects are used to derive relative indices of the herring abundance. The S a values are extrapolated to the surveyed region using geostatistical methods. The Sa values are converted to abundance by calculating mean herring lengths from trawl catches, converting the mean lengths to target strength (TS) using a generic Atlantic herring TS-Length regression. Biomass estimates are derived by scaling the abundance estimates by an empirical length-weight relationship. Agebased estimates are derived from the age composition of the trawl catches. 56
Methods Calibration and System Performance Calibration Techniques Software The NEFSC uses the Simrad Lobe program, version EK/EY500 5.XX (date of last revision: 30 October 1995) to calibrate the EK500 echo sounder. The calibration software version and the echo sounder firmware version are documented for all calibrations. Standard values Table 1 provides a list of standard values for calibration. Table 1. Calibration standard values used at the NEFSC. Frequency [kHz] Calibration Sphere EK500 Minimum Target Range [m] Nominal TS [dB]* 12 45 mm Cu 35 -40.4 18 64 mm Cu 22 -34.4 18 63 mm Cu 22 -34.4 38 60 mm Cu 10 -33.6 120 23 mm Cu 10 -40.4 Calibration sphere measurements are the sphere diameter. ‘Cu’ denotes a copper calibration sphere. Note that the 18 kHz has two spheres listed. Simrad originally recommended the 63-mm sphere. However, after consultation with Neal Williamson (NOAA-Fisheries, AFSC) and Ken Foote (WHOI) during the fall of 2003, the 64-mm Cu sphere was determined to be the optimal sphere. The 64-mm Cu will be used from 2004 on. The 12-kHz echo sounder was replaced in 2002 with the 18-kHz echo sounder. On-axis sensitivity The NEFSC acoustics manual (NEFSC_aqstx-acoustics_manual.doc) details on-axis calibration protocols. The tolerance of the 38-kHz on-axis calibration is ±0.4 dB (G 0 : ±0.2 dB). Transceiver settings are equivalent to those used during the survey. Beam pattern measurements The NEFSC acoustics manual (NEFSC_aqstx-acoustics_manual.doc) details beampattern measurement protocols. The NEFSC does not modify the offset or beamwidth parameters based on the LOBE program. This is due to the concern that the beam pattern parameters derived by the LOBE program are not based on independent measurements of the beam pattern. The LOBE program relies on the angular offsets provided by the EK500 and transducer, which is not an independent measure of the true angular positions. Transceiver settings are equivalent to those used during the survey. 57
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NOAA Protocols for Fisheries Acoust
Page 4 and 5:
Echo Sounder Parameters ...........
Page 6 and 7: Trawls ............................
Page 9: Introduction In response to Vice Ad
Page 12 and 13: Advanced Survey Technologies Progra
Page 14 and 15: Techniques Before conducting a cali
Page 16 and 17: Considerations Remediation Echo sou
Page 18 and 19: transmission loss. To correct for s
Page 20 and 21: unavoidably discarded, just as some
Page 22 and 23: factors such as orientation are not
Page 24 and 25: A schedule for calibration and main
Page 26 and 27: Techniques Noise Acoustical A commo
Page 28 and 29: ⎛ I ⎞ r TS ≡ 10 log10 ⎜ ⎟
Page 30 and 31: Considerations Remediation If a TS-
Page 32 and 33: Techniques Beam Pattern Transducers
Page 34 and 35: during vertical migration, will cau
Page 36 and 37: A schedule for calibration and main
Page 38 and 39: degradation are external to the ech
Page 40 and 41: permanently archived for each surve
Page 42 and 43: Numerical Density to Biomass Densit
Page 44 and 45: An electronic ‘event log’ can b
Page 46 and 47: References Demer, D.A., M.A. Soule,
Page 48 and 49: Regional Protocols Because of the d
Page 51 and 52: Table of Contents Introduction.....
Page 53: Electrical ........................
Page 58 and 59: S v Calibrations The NEFSC acoustic
Page 60 and 61: Operation Menu/Transmit Power Norma
Page 62 and 63: Software The echo sounder firmware
Page 64 and 65: ii. Minimum Sv for good pick: -50.0
Page 66 and 67: Net mensuration sensors are attache
Page 68 and 69: We remove backscattering by surface
Page 70 and 71: GPS The primary Global Positioning
Page 72 and 73: Electrical Electrical noise protoco
Page 74 and 75: Scientific Computer System (SCS) Fi
Page 77: Appendix 2 March 11, 2005 NOAA Prot
Page 80 and 81: Techniques ........................
Page 82 and 83: Center Background AFSC The Alaska F
Page 84 and 85: On-axis sensitivity and S v calibra
Page 86 and 87: Volume Backscattering Measurements
Page 88 and 89: Mid-water juvenile pollock (max sa=
Page 90 and 91: Biological Sampling Mid-water and n
Page 92 and 93: Bubble Attenuation Vessel speed is
Page 94 and 95: Data Collection Since 1990 to the p
Page 96 and 97: sampling resolution of scattering l
Page 98 and 99: A decision must be made as to wheth
Page 100 and 101: design. If fish abundance in this a
Page 102 and 103: Simrad. 2001. Simrad EK60 scientifi
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Acoustic Data......................
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ackscattering cross-section (σ i )
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o For the 38 kHz transducer operati
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• Two-way integrated beam pattern
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Classification Techniques Single Fr
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Performance Degradation Definition
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Biological Data Data from catch pro
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elation also assumes that backscatt
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finer than the 13.5-18.9 nmi (25-35
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Improvements - The annual hake migr
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Techniques The primary source of th
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Hamano, A., Sasakura, T., Kieser, R
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