International Bottom Trawl Survey Jellyfish Data - North Sea - 2012 to 2023

notPlanned

Jellyfish data was collected using standard GOV fishing gear deployed from Cefas RV Endeavour, to carry out the International Bottom Trawl Survey (IBTS) since 2012. Cefas is responsible for the Quarter 3 (Q3) survey which is recurring every August and covers the North Sea. The IBTS is a fishery dependent multi-species bottom trawl survey coordinated within ICES areas. These surveys aim to provide ICES assessment and science groups with consistent and standardized data for examining spatial and temporal changes in (a) the distribution and relative abundance of fish and fish assemblages; and (b) of the biological parameters of commercial fish species for stock assessment purposes. Full details of protocols are described in the official manual: `https://www.ices.dk/sites/pub/Publication%20Reports/ICES%20Survey%20Protocols%20(SISP)/SISP1-IBTSVIII.pdf`_ Following each fishing trawl described in the protocol, gelatinous zooplankton (commonly known as jellyfish) collected in the net were processed similarly to the fish. The rationale for the sampling of jellyfish is explained in Aubert et al. 2018 (`https://doi.org/10.1016/j.marpol.2017.12.010`_), which also contains the official standard operating protocol to process the gelatinous zooplankton. Gelatinous zooplankton were separated according to species. The bulk of each species was weighted with individuals also weighted and measured. Unrecognisable specimen were categorised into a "non-identified" category. .. _`https://www.ices.dk/sites/pub/publication%20reports/ices%20survey%20protocols%20(sisp)/sisp1-ibtsviii.pdf`: https://www.ices.dk/sites/pub/Publication%20Reports/ICES%20Survey%20Protocols%20(SISP)/SISP1-IBTSVIII.pdf .. _`https://doi.org/10.1016/j.marpol.2017.12.010`: https://doi.org/10.1016/j.marpol.2017.12.010