Acoustic investigation had been built-up about NOAA Boat Nancy Foster inside the echosounder doing work from the 3 frequencies (38, 120, two hundred kHz). Pulse length is set to 128 ?s into the 120 kHz and two hundred kHz and you will 256 ?s into 38 kHz. I interviewed a maximum of eight programs as well as each station a keen acoustic survey is actually frequent six moments more than day (pre-dawn, post-start, daytime, pre-dusk, post-dusk, nighttime; as much as step 1.5 times per questionnaire). The fresh new questionnaire structure consisted of seven parallel transects 1 nm (step one.852 km) much time and you can separated fifty meters apart (Fig step 1). The newest ship rate is actually everything 6.5 tangles. Up to 7 nmi of song lines was basically surveyed per out of brand new six sampling cycles (ca. 50 nmi full) within eight programs. Predator and sufferer densities was indeed estimated for each and every of your studies as well as the diel development of fish density try standardized because of the testing web site.

The device is actually calibrated before the sail adopting the standard measures having fun with an effective tungsten carbide areas

The latest spatial and you may temporal variability in the study town was higher.Read More