KRILLBASE-length frequency database, a compilation of scientific net sampling data on length, sex and maturity stage of Euphausia superba around the Southern Ocean, 1926 to 2016

The KRILLBASE-length frequency database comprises individual length measurements of 613487 Euphausia superba from 6470 scientific net hauls. Some of these individually-measured krill have additional information on their sex and maturity stage. Most of these E. superba are postlarvae, but some of the hauls include small (< 20 mm) krill which likely include furcilia larvae as well as juveniles. Much of these data were compiled at British Antarctic Survey in 2007 by Mark Jessopp, with additional compilation by Angus Atkinson, Catherine Brewster and Natalie Ensor, and later data checking by Angus Atkinson with Helen Peat. The circumpolar distribution of records is illustrated in the file KRILLBASE_LF_DISTRIBUTION that is available along with this dataset. Examples of uses of KRILLBASE-length frequency are in Atkinson et al. (2009), Tarling et al. (2016), Perry et al. (2019) and Atkinson et al. (2019). The KRILLBASE-length frequency records were provided by contributing authors of the database or transcribed from the literature or from other institutional databases. At the time of data compilation, data from commercial-size large mesh trawls and from the commercial fishery was also transcribed, providing valuable information on the larger krill caught by these nets. These data are not included in this current KRILLBASE-length frequency database version, because of the difficulty in comparing them with the finer mesh scientific nets compiled here, and because length and population structure are also available in more complete form from CCAMLR. The KRILLBASE-length frequency database forms a complementary database to the KRILLBASE-abundance database (doi:10.5285/8b00a915-94e3-4a04-a903-dd4956346439), which compiles the abundance of Euphausia superba and salps in the Southern Ocean (Atkinson et al 2017). Both databases are multi-national, circumpolar compilations of net samples spanning years 1926 to 2016. The KRILLBASE-length frequency database uses some of the stations as KRILLBASE-abundance but also additional ones from targeted hauls or horizontal hauls.