Age validation of lemon sole (Microstomus kitt), using marginal increment analysis

•Age validation has never been carried out on lemon sole (Microstomus kitt).•Marginal increment analyse was carried out on the otoliths.•The results showed that a single annulus represents one year of growth.•These results provide greater confidence in age estimation.

Age estimation of the commercially valuable flatfish lemon sole (Microstomus kitt), has traditionally been estimated from otoliths using the ‘breaking and burning’ technique. Perceived annual incremental growth has never been validated for this species, however. Here, the otoliths from 838 lemon sole collected from the North Sea, English Channel and Celtic Sea throughout entire months of 2009 were analysed. The periodicity of increment formation was examined using marginal increment analyses (MIA). No incremental growth was observed between January and March for any size class. Incremental growth generally commenced earlier in younger fish (April in ages 3–5) and later in older fish (May for ages 6–10, June for ages 11+). The results clearly demonstrate that a single annulus represents one year of growth. These results inform best practice, and provide greater confidence in age estimation and consequently, the quality of data used in the assessment of the stock.