The other main finding of our analysis was that, at the time of
the survey, individuals of both species were on average twice as
heavy (as indicated by the average mass per individual) in the
west than in the east (Fig. 3). This might be linked to phenological
differences in the timing of the primary production season
in different regions of the Irish Sea. Coastal areas in the
western part of the basin (east coast of Ireland) are known to
have a production season starting early in the year (MarcheApril)