This dataset contains biological measurements of 338 individuals of the North Atlantic myctophid Notoscopelus kroyeri (Krøyer's lantern fish). Individuals were collected opportunistically as bycatch in pelagic trawls (surface and deep) during the Icelandic portion of the International Ecosystem Summer Survey of Nordic Seas (IESSNS) conducted in south Icelandic waters and the Irminger Sea in July 2020 and south and west Icelandic waters in 2021. Frozen samples were processed on land in 2022 from twelve trawl stations located in four IESSNS strata regions (5, 6,11, and 12). Further details on the trawl methodology, sampling and associated environmental variables can be found in related to references and two survey reports (Ólafsdóttir and Kennedy 2020, Ólafsdóttir et al. 2022). Observations include multiple length and weight measurements, as well as otolith morphometrics, including otolith length, width and area. Otoliths were photographed on a matte background, proximal side down, and the left otoliths were measured using ImageJ software (if only the right otolith was present, this was used). The data is provided by the Marine and Freshwater Research Institute (MFRI) in Iceland.