Ping360 scans obtained in a commercial sea cage rearing Atlantic salmon (Salmo salar)
Description
This dataset contains a sample of the raw data (excel files) obtained from a mechanical 360-degree scanning sonar (Ping360 Scanning Image Sonars, Blue Robotics Inc., California, USA) deployed in a commercial sea-cage (140 m circumference, 27 m depth, the upper 15 m cylindrical + 12 m conical; a lice skirt was mounted to 5 m depth) rearing Atlantic salmon (Salmo salar) in Norway. Fish were just transferred from the land-based facility to the sea cage, and we wanted to follow the evolution in their behavior (vertical and horizontal distribution) their first month at sea. Fish were on average 510g (post smolts) and density in the cage at the start was 4.3 kg/m3. Due to storage limits, 3 full days (24 h each) are included (one folder per date). Raw data from 38 days (not always 24h continuous) is available on request but all scans from the raw data are presented as videos (10 images per sec) in the folder "All videos from complete dataset". Description xlsx files: Timestamps are in CET and embedded in filenames (yyyymmdd_hhmmss-x). First column: angle (radians, 0–399) First row: distance (0–1199, equal to 30 m) Remaining cells: echo strength (Analog-to-Digital Converter values, 0–597) Folder "Data processing": Includes a Python script to plot sonar data, input/output examples, and a labeled scan ("Scanwithexplanations.png") in polar coordinates. The sonar is in the middle of the figure. The circular lines show the distance from the sonar and each line corresponds to a 5 m distance. Apart from the visible cage structures (cage walls, cone leading to the cage bottom and water surface), observations inside the cage are salmon. Any visible echo strength above the water surface corresponds to echo reverberation on the surface. Cage deformation due to current is also visible on the scans and examples of deformed and undeformed cage are provided in the folder "Cage deformation". Folder "Water current": Excel file with two sheets: Horizonspeed = overall sideways movement of the water in cm/sec Eastspeed = current in the eastern direction in cm/sec First column: timestamp (dd.mm.yyyy HH:MM in UTC) First range: depth (in meters) Data collected on one of the most exposed buoys of the fish farm's mooring frame.
Files
Steps to reproduce
A mechanical 360-degree scanning sonar (Ping360 Scanning Image Sonars, Blue Robotics Inc., California, USA) was mounted on a 50 m long tether cable to be connected to a PC on the rig of the sea cage. Initially used for horizontal scanning to detect obstacles for ROVs, the Ping360 was placed in the center of the sea cage at 7 m depth to scan vertically with a range of 30 m and thus, to scan an entire segment of the sea cage. We provide visualizations of the studied sea cage (see folder "Experimental set up") at scale with the Ping360 theoretical 360 degrees scan coverage from three different point of views (done on www.sketchup.com). The lice skirt and the full set of 400 pings are not fully represented for better visibility. Each scan took approximately 35 seconds to be completed. xlsx files: Pretreatments have been performed on the files provided using Python (V3.8). After extraction, each ping was assigned its correct time stamp, and jumps in the dataset i.e. duplicates of same rotational angle, were discarded. Scans were separated into individual files with a corrected rotation applied in order to get the water surface horizontal for a more intuitive interpretation when plotting the scan (with angle 0 = north).