This manual describes the coordinated survey design for Baltic international trawl surveys. Randomly stratified fishing-stations location is based on ICES subdivisions and their depth layers as strata to reflect the variability of the Baltic target species temporal-spatial distribution pattern. Besides the traditional Baltic International Trawl Survey (BITS-Q1) in February-March additional coordinated, routine survey (BITS-Q4) has been conducted in November, since 2001. The above-mentioned demersal trawl surveys are coordinated by the ICES WGBIFS. The surveys aimed to the monitoring of the spatial distribution and year-classes abundance of the demersal species, i.e. cod (Gadus morhua), flounder (Platichthys flesus) and other flatfish (plaice - Pleuronectes platessa, turbot - Scophthalmus maximus, dab - Limanda limanda, brill - Scophthalmus rhombus) and to some extent to clupeids (sprat - Sprattus sprattus and herring - Clupea harengus) in the Baltic Sea. WGBIFS agreed in 2009, that data of all analysed fish are uploaded to the ICES Data-base of Trawl Surveys (DATRAS) to support the Baltic ecosystem analyses, taking into consideration ICES subdivisions and rectangles codes.
Published under the auspices of the following ICES Steering Group or Committee
EOSG
Published under the auspices of the following ICES Expert Group or Strategic Initiative
WGBIFS
Series
ICES Survey Protocols
Volume
7
ISBN
978-87-7482-202-8
ISSN
2304-6252
Recommended citation
ICES. 2017. SISP 7 - Manual for the Baltic International Trawl Surveys (BITS). Version 2. Series of ICES Survey Protocols. 95 pp. http://doi.org/10.17895/ices.pub.2883