Seasonal movements of veined squidLoligo forbesiin Scottish (UK) waters

Abstract

-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.

World Squid Fisheries

“…In some years a West-East migration apparently occurs in autumn in Scottish waters (Waluda and Pierce, 1998). In the Moray Firth, Scotland, the smallest individuals are caught close inshore in summer and there seems to be a subsequent ontogenetic migration away from the coast and a later return of mature animals into coastal waters to spawn (e.g., Viana et al, 2009). Several studies in Scotland have reported two main recruitment periods, in April and November, with small numbers of recruits present throughout most of the year, despite there apparently being a single main breeding season (Lum-Kong et al, 1992;Boyle and Pierce, 1994;Pierce et al, 1994b;Boyle et al, 1995;Collins et al, 1997Collins et al, , 1999.…”

“…Perhaps the most realistic approach, considering the continued dominance of landings from bycatch fisheries, is for management to focus on protection of essential habitat such as spawning areas rather than on generic catch or effort limitations. Recent modeling work has attempted to define habitat and movements of L. forbesii in Scottish waters (Viana et al, 2009;Smith et al, 2013) but the main spawning areas of this species remain to be identified. Many records exist of Loligo spp.…”

Climate change and squid range expansion in the North Sea

“…This expansion and increase in abundance were correlated with several climatic variables, including the AMO, but most strongly with a direct effect of annual North Sea SST. This was expected given the short life cycle of squid, and close links demonstrated between the spatial distribution of Loligo and warmer sea temperatures in Scottish waters (Waluda & Pierce, ; Viana et al ., ) and the Celtic Sea (Denis et al ., ). During winter in waters around Scotland, L. forbesii was shown to be absent from areas with temperatures lower than 7 °C (Pierce et al ., ).…”

Biology and meso-scale distribution patterns of North Sea cephalopods

“…More recently, distribution patterns, seasonal migrations, and interannual trends in abundance related to oceanographic factors such as water temperature have also been investigated in North Sea squid (e.g. Waluda and Pierce, 1998;Robin and Denis, 1999;Bellido et al, 2001;Pierce and Boyle, 2003;Zuur and Pierce, 2004;Pierce et al, 2008;Viana et al, 2009). Information on the distribution and abundance of cephalopods in North Sea regions other than the English Channel and around Scotland remained poor and was mostly added to reports on the Scottish squid fishery (Thomas, 1969;Thomas and Davidson, 1972;Howard, 1979;Howard et al, 1987).…”