Baltic International Acoustic Survey Report, R/V Svea, Sweden : survey 2022-10-02 - 2022-10-17

Abstract

Internationally coordinated hydroacoustic surveys in the Baltic Sea have been operated by the Institute of Marine Research in Lysekil since 1978. The Baltic International Acoustic Survey (BIAS), is performed annually in October. The survey is mandatory for each EU member state around the Baltic Sea, and is regulated under the European Commission's Data Collection Framework (DCF). Sweden is responsible for collecting data from subdivision (SD) 27 as well as parts of SD 25, 26, 28, and 29. The purpose of the expedition is to assess the stock status of herring and sprat, and this is done by producing an index of abundance each year. The results are reported annually to the International Council for the Exploration of the Sea (ICES) working groups Baltic International Fish Survey (WGBIFS) and the Baltic Fisheries Assessment (WGBFAS).

The 2022 survey was carried out with R/V Svea and commenced with echo sounder calibration on October 2, in Gåsfjärden (57°34.5 N, 16°35.0 E), after which the vessel headed eastward to SD 27 where the data collection started. The survey finished on October 17, in Kalmar (56°40.0 N, 16° 21.0 E). Through the survey, acoustic raw data was continuously collected using a scientific echo sounder (EK80 38 kHz). Biological data was collected through pelagic trawling to obtain information on species composition and length distribution. Acoustic raw data were post-processed using the Large Scale Survey System (LSSS) software. The trawl catches are analyzed for species composition and length distribution, and the target species herring, sprat, and cod were also analyzed to determine the age structure of each stock. The information on species and lengths from the trawl catches was integrated with the acoustic data to calculate an index of abundance of the fish species.

Guidelines and manuals are managed by WGBIFS and results from each country are compiled into a database. The results are used as an index of abundance by WGBFAS in the estimation of the total stock status of herring and sprat in the Baltic Sea. The results for BIAS were accepted by the WGBIFS and added to the index. Previous results and more information about BIAS and WGBIFS work can be found in the annual reports of the WGBIFS working group.

Keywords

herring; sprat; acoustic; index; Baltic Sea

Published in

Aqua notes
2024, number: 2024:29
Publisher: Department of Aquatic Resources, Swedish University of Agricultural Sciences

SLU Authors

• Larson, Niklas

  • Department of Aquatic Resources (SLU Aqua), Swedish University of Agricultural Sciences
    

UKÄ Subject classification

Fish and Aquacultural Science

Publication identifier

• DOI: https://doi.org/10.54612/a.8iepsnfeb6
• eISBN: 978-91-8046-666-0

Permanent link to this page (URI)

https://res.slu.se/id/publ/139228