Integrated hull mounted multi-frequency acoustic data, biotic and oceanographic data from Marine Institute, Ireland Cruise: Multidisciplinary Mesopelagic Scouting Survey Cruise (M2S2)
Description
A dedicated Multidisciplinary Mesopelagic Scouting Survey (M2S2) took place onboard the RV Tom Crean in September 2022 on the shelf slopes of the Rockall Trough. The survey was carried out to collect information on the spatial extent and temporal persistence of any aggregations using a replicate line transect survey design. Multi-frequency acoustic data (18, 38, 70 and 120 kHz) were collected on aggregations and scattering layers in the upper mesopelagic zone during daylight hours. Directed trawling on insonified layers was carried out to determine species composition and collect biological metrics on key species including, M. mulleri and B. glaciale. Trawling was carried out using a trawl utilizing a graded small mesh design to sample small active swimming mesopelagic fish. The survey collected depth stratified water samples by vertical CTD cast for environmental DNA sampling purposes and trialed on-board analysis procedures for near real-time interpretation of echograms.