The present work explores four years of quantitative spatiallyexplicit
bycatch data of Aurelia aurita and Cyanea spp. in the Irish
Sea with three specific objectives: (1) to provide the first speciesspecific
quantitative estimates of jellyfish biomasses in the Irish
Sea and a description of their distributions; (2) to examine whether
inter-annual variations of biomass are consistent across the Irish
Sea; and (3) to check whether these are linked to variations in
number of individuals or of the size of the individuals. Beyond the
specific case of the Irish Sea, these last two points should provide
further elements on the importance of considering regional and
local scales when studying jellyfish temporal dynamics (Dawson
et al., 2014), as well as on the vulnerability of bycatch datasets to
phenological changes