Arctic | Fishes and Fish Habitats
A nearshore Arctic Ecosystem Observatory (2018-present)–preliminary results Presenter: Leandra Sousa , leandra.sousa@north-slope.org, North Slope Borough Dept. of Wildlife Management Nicholas Ens , ensnicholas@gmail.com, Department of Biology, University of Victoria Stephane Gauthier , Stephane.Gauthier@dfo-mpo.gc.ca, Institute of Ocean Sciences, Fisheries and Oceans Canada Todd Sformo , todd.sformo@north-slope.org, North Slope Borough Dept. of Wildlife Management Billy Adams , billy.adams@north-slope.org, North Slope Borough Dept. of Wildlife Management Matt Stone , mstone@aslenv.com, ASL Environmental Sciences Jeremy Lawrence , jlawrence@aslenv.com, ASL Environmental Sciences A bottom mounted mooring has been deployed and recovered annually since 2018 in a nearshore (< 1 Km from shore) shallow (14 meters depth) site near Plover Point near Utqiaġvik Alaska. The mooring is equipped with an Acoustic Zooplankton and Fish Profiler (AZFP) operating at 38, 125, 200 & 455 kHz (2018-present), CTD (2018-present), Wave Logger (2019-present) and ADCP (2021-present). CTD casts and under-ice net sampling began in spring 2022, when fish and zooplankton were collected to verify acoustic targets. The goals of this project were to investigate the presence of Arctic Cod spawning in Arctic Lagoons and associated environmental variables (temperature, salinity, and pressure), and to determine under-ice seasonal changes in zooplankton, and fish volume backscatter in relation to water mass parameters, and currents. We present preliminary AZFP data analyses for 2018-2019 as well as under-ice survey methods used in spring 2022. Zooplankton nautical area scattering coefficient (NASC – a proxy for biomass) was low from November (avg. temp. -1.89°C and salinity 30.48) to June (avg. temp. -0.33 and salinity 30.21), with a peak in abundance from 10-25 June prior to ice break up. Zooplankton were scattered throughout the water column in November and began aggregating in increasingly distinct layers from March to June. The abundance of single fish targets peaked in November during freeze-up and gradually declined until April and peaked again in June. Under ice sampling of fish and zooplankton was conducted every 4 days using ring nets and gillnets from April to June 2022. Copepods and juvenile euphausiids were collected throughout the sampling period while; larval fish began to occur in June. Ostracods, pterapods, chaetognaths, and amphipods started to occur by mid-May and were intermittently present. Currents and water clarity were highly variable during the surveys. Further analyses of ADCP, sea level and surface wind measurements in conjunction with additional years of AZFP and net sampling data are planned. These results will help us better understand the relationships between environmental parameters associated with changes in the relative abundance, biomass, and diversity of under ice fauna in the Arctic nearshore.
Alaska Marine Science Symposium 2023 223
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