2023_programme: A year in the life of zooplankton and fish in the Gulf of Maine: Long (and short) term monitoring of pelagic organisms using bottom-mounted, upward-looking, multifrequency echosounders

• Session: 05. Marine Bioacoustics
  Organiser(s): Jennifer Miksis-Olds
• Lecture: A year in the life of zooplankton and fish in the Gulf of Maine: Long (and short) term monitoring of pelagic organisms using bottom-mounted, upward-looking, multifrequency echosounders [invited]
  Paper ID: 2007
  Author(s): Warren Joseph, Lucca Brandyn, Escalante Monique, Lyons Anthony
  Presenter: Warren Joseph
  Abstract: Bottom landers containing upward-facing broadband, multifrequency (38, 120, and 200 kHz) echosounders were deployed at two sites in the Gulf of Maine for ~11 months each. The instrument deployed at Wilkinson Basin collected data from mid-February 2021 to January 2022, while the instrument at the Northeast Channel site sampled from January 2022 to late November 2022. Both systems recorded water column backscatter data for 2 minutes every hour. Fine-scale (5 km by 5 km) vessel-based echosounder surveys were conducted at each site to provide additional information about the spatial extent of scattering features. Hydrographic profiles and vertical ring net tows at each site during deployment and/or recovery provided additional environmental information. In addition to examining the single frequency data, classification algorithms were used to partition the backscatter by the likely scatterer type: small or large fluid-like scatterers (i.e. copepods, krill, shrimp, fish without swimbladders) or swim-bladdered fish. This technique allows us to collect data on multiple taxonomic groups (including multiple trophic levels) simultaneously. These processed data were then used to examine a variety of oceanographic processes including: rapid increases (but at different times) in the abundance of near-surface organisms during the spring and fall blooms; variability in the abundance and biomass of demersal fish; possible detection of copepod diapause; the creation/dissipation and spatial characteristics of internal wave trains; and, in some situations, the presence of marine mammal predators. The advantages (and challenges) of using moored echosounders as part of ocean ecosystem observatory systems will be discussed.
• Corresponding author: Dr Joseph Warren
  Affiliation: Stony Brook University
  Country: United States
  e-mail: