DOI: 10.24431/rw1k5bc
title: Data from experimental estimation of catchability of the combined bottom trawl and acoustic survey for walleye pollock (Gadus chalcogrammus) in the Eastern Bering Sea, 2018

description: This project experimentally estimated the catchability (i.e. the coefficient measuring catch efficiency in relation to actual population size) of a combined bottom trawl (BT)-acoustic survey. Data from this project is organized into 5 subfolders: BOAT DATA Acoustic data collected from the F/V Alaska Knight during 2018 in the Bering Sea to compare to data collected during the same time from tow body towed behind Alaska Knight vessel. This raw data was collected using 38/120 kHz hull-mounted Simrad ES60 echosounder with 7° beamwidth Simrad model ES38B and ES120-7C transducers mounted ~ 10 m aft of the bow of ship. File formats are .raw, .out, .EV and .csv. .raw files contain the recorded echogram, while .out files contain the recorded bottom information. .EV files contain processed acoustic data that can be accessed using Echoview. The .csv files are the exported numerical data from the acoustic data that was processed in Echoview. The file AK_Knight_2018_1m_by_30_sec_revised.csv is the source of all data used for the vessel in this study. ROC DATA Acoustic data collected from the Remotely Operated Catamaran (ROC) towed behind trawling vessel during 2018 in the Bering Sea to compare to data collected during the same time from trawl vessel Alaska Knight. This raw data was collected using a battery-powered 120 kHz Simrad EK60 scientific echosounder. File formats are .raw, .idx, .bot, .EV, .txt and .csv .raw files contain the recorded echogram, while .bot files contain the recorded bottom information. .idx files contain some other data that is not used by echoview. .EV files contain processed acoustic data that can be accessed using Echoview. The .txt files includes information about the calibration procedure. The .csv files are the exported numerical data from the acoustic data that was processed in Echoview. The file ROC_2018_1m_by_30_sec_revised.csv is the source of all data used for the ROC in this study. ROC FIELD NOTES Data collection field notes collected during 2018 in the Bering Sea These field notes were collected on paper forms during data collection and using a proprietary event marking program. File formats are .xlsx and .docx. The .xlsx file shows events that were recorded during data collection, while the .docx files are transcriptions of the hand written notes recording during the data collection. SEABIRD & MARPORT FILES Auxiliary data collected from the F/V Alaska Knight in the Bering Sea during Summer 2018. A Marport Deep Sea Technologies Inc. net mensuration system was used to record net spread and net height and confirm that the net width and net height were within the range normally observed during standard survey trawls. A Seabird CTD was used to collect environmental data. File formats are .BTD, .BTH, and .marp. .BTD files contain the recorded temperature and depth information, while the .BTH file contains all the header information. The .marp files contain net height, depth, temperature and gps data. TOW BODY TILT SENSOR FILES Tilt data was collected from the tow body being towed behind the F/V Alaska Knight during 2018 in the Bering Sea to ensure the acoustic transducer remained level during times of data collection. This data data was collected using an Onset HOBO Pendant G Tilt sensor that was affixed to the tow body. File formats are .csv and .hobo. .csv files contain tilt and acceleration values for each axis at one second intervals, while .hobo files can be opened with Onset's hoboware software and contain tilt and acceleration data. Additionally, there is a README file that describes how to reach out for access to the raw acoustic data.