CalCOFI 1210NH Cruise Data. In California Cooperative Oceanic Fisheries Investigations (CalCOFI): Acoustic and Trawl Data

Acoustic backscattering data were collected between stations using a hull-mounted Simrad EK60 split-beam echo sounder equipped with five frequencies (18, 38, 70, 120, and 200kHz). The EK60 was calibrated before each cruise using the standard sphere method (Foote et al., 1987). Pulse length was set to 1.024ms with a ping rate of 0.5s_1. Beam angles were 71 for the 38kHz transducers and111 for the 18 kHz. Power for both 18 and 38kHz transducers was 2kW. As the three highest frequencies did not reliably penetrate to the depth of the daytime deep scattering layer (DSL) at the vessel transit speed (10knot), they were not used in this study. Acoustic data were processed and noise removed using Echoview software. Nautical area scattering coefficient (NASC) was calculated over 100m distance segments by 5m depth intervals. See Davison et al. (2015a) for further details of acoustic data analysis methods.

声学后向散射数据通过船载Simrad EK60分裂波束回声测深仪在站点间采集，该仪器配备五种频率（18、38、70、120和200kHz）。每次巡航前使用标准球体法（Foote等，1987）对EK60进行校准。脉冲长度设置为1.024毫秒，ping率为0.5次/秒。38kHz换能器的波束角为7.1度，18kHz换能器的波束角为11.1度。18和38kHz换能器的功率均为2千瓦。由于在船舶航行速度（10节）下，三种最高频率无法可靠穿透至日间深层散射层（DSL）的深度，因此本研究未使用这些频率。使用Echoview软件对声学数据进行处理并去除噪声。按100米距离段和5米深度间隔计算了航海区域散射系数（NASC）。声学数据分析方法的更多细节请参见Davison等（2015a）。