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This data set has trawl catch weight and biological measurements from the 2nd leg of the Icelandic part of the International Ecosystem Summer Survey in Nordic Seas (IESSNS) conducted in July 2019. The survey area was from the coast, over the shelf edge and into the deep-water basins south and west of Iceland, defined as IESSNS strata 5, 6, and 12, and stratum boundaries (black solid line) are displayed on attached map "IESSNS 2019.png". The survey period is July 16 - 28 2019, and samples were collected at 34 trawl stations (blue symbol on attached map). A specifically designed scientific trawl, called Multpelt832 (ICES, 2013a-b, Valdemarsen et al 2014) with cod-end mesh size of 50 mm, was used at all 34 stations. Trawl depth ranged from surface (trawl headline in surface) to 370 m depth. All trawl catch was identified to lowest possible taxonomic level, total weight of each species recorded and length of 20-50 specimen per species measured. For blue whiting (Micromesistius poutassou) more biological measurements are provided such as weight, sex, maturity, age, and stomach weight. For age determination, the otolith was extracted whole from the blue whiting at sea and read whole under a dissecting microscope on land by an experienced age reader part of the ICES framework. Gonad maturity stage was visually estimated at sea during sampling by an experienced technician. The maturity stages are 1-7, where 1 is immature, 2 is beginning to mature or beginning to recovering from previous spawning event, 3 is maturing, 4 is maturing, 5 is getting fully mature, 6 is spawning, and 7 has finished spawning. In total, measurements are provided for 857 specimen. Each specimen is one row in the dataset file. Ten specimen, at eight stations (352, 354, 361, 366, 375, 383, 388, 391) were not length measured but are included and total weight of catch per taxon or species per station is provided. Information for three pelagic fish species is excluded from the data set and these species are mackerel (Scomber scombrus), herring (Clupea harengus) and lump fish (Cyclopterus lumpus). For detailed information about the survey, see the survey report (in English): https://www.hafogvatn.is/is/midlun/utgafa/haf-og-vatnarannsoknir/results-of-the-icelandic-part-of-the-international-ecosystem-summer-survey-in-nordic-seas-iessns-in-2019-on-rv-arni-fridriksson-hv-2019-57. Various information is provided about the trawling operation, weather, position, date and time. The data are provided by the Marine and Freshwater Research Institute (MFRI) in Reykjavik, Iceland.