West Coast of Scotland - Environment

The currents within ICES Division VIa are strongly influenced by ocean circulation in the wider north-eastern Atlantic and in particular by the strength of the North Atlantic current (NAC). Observations in the Rockall Trough show that between the 1960s-1990s waters have tended to be cool and relatively fresh but from the mid-1990s there has been a period of warming and increasing salinity.

Longer term observations are available from the Tiree passage mooring and some inshore stations. These show the mean water temperature to be around 10-11°C with clear seasonal fluctuations of around 3°C. There has been a sequence of alternate cooling and warming periods but with an overall trend for increasing temperatures at a rate of 0.57°C per decade up to 2004. However, since then, the rate of warming appears to have slowed as seen offshore.