In order to protect and sustainably manage fishery resource species, it is
essential to understand their movements and habitat use. To detect the
hypothesised migration of maturing veined squid Loligo forbesi from the west coast of
Scotland (UK) to the North Sea and identify possible inshore-offshore
movements, we analysed seasonal, spatial and environmental patterns in
abundance and size distribution, based on commercial fishery landings data
and trawl survey data from Scottish coastal waters (International Council
for the Exploration of the Sea, ICES areas IVa, IVb and VIa). A geographic
information system (GIS) was used to build monthly contour maps of
abundance. Generalised additive mixed models (GAMM) were used to quantify
patterns in size distribution and abundance. In most years, there was no
evidence of movement from the West to the East coast of Scotland. Evidence
of inshore-offshore movements during the life-cycle of the cohort that
recruits in autumn (winter breeders) was found instead. The winter breeding
cohort appears to spawn in inshore waters and some evidence suggests that
the spawning grounds of the summer breeders are also inshore. Across
seasons, higher abundance of L. forbesi can generally be found in the north of
Scotland at intermediate water depths and in warmer waters.