Significant differences in length were detected between areas (ANOVA F = 94.93, p-value < 0.001) (Fig. 4). In order to confirm that growth differences between areas did not arise due to the observed length differences, the dataset was reduced so that the length distributions of fish from Bay of Biscay and South Ireland overlapped. The spatial variation in growth revealed by the growth model comparison was also apparent when growth rates were compared between locations within the common body size range (ANOVA F = 7.023, p-value = 0.01); with mean growth rates of 1.13 mm/day for fish from south Ireland and 0.96 mm/day for the Bay of Biscay samples. Samples from south Ireland were captured using three fishing methods (purse seine, trawl and gillnet) while all samples from the Bay of Biscay were caught by purse seine. To ensure that the observed differences in growth and length between areas was not an artefact of the sampling methods used (due to differences in the selectivity of the various gears), the two areas were compared using only fish that had been collected by purse seine; the differences in length persisted (ANOVA F = 104.9, p-value < 0.001).