Fisheries bycatch data provide insights into the distribution of the mauve stinger (Pelagia noctiluca) around Ireland

There is concern that jellyfish populations are proliferating in the Northeast Atlantic and that their socio-economic impacts will increase. Using information from the Irish Groundfish Survey, data are presented on the distribution of the mauve stinger, Pelagia noctiluca, over an area >160 000 km² around Ireland and the UK in 2009. The species accounted for 93% of the overall catch of gelatinous organisms, with an average catch biomass of 0.26 ± 2.3 kg ha−1. The study area was divided into four subregions (North, West, Southwest, and South), and the distribution and abundance of P. noctiluca displayed both inter- and intraregional variations. Individual bell diameters ranged from 1 to 13.5 cm (median 4.5 cm, s.d. 1.2 cm), and the size distribution also varied spatially. It is the first time that such detailed information has been made available for P. noctiluca in a part of the Northeast Atlantic where its impact on the salmon aquaculture industry can be considerable. Finally, the possibility of using annual datasets from this type of fisheries survey to develop time-series that, in the future, will allow investigation of relationships between long-term variations of P. noctiluca populations and climatic factors in the area is addressed.