Scotland's seas support a diverse array of habitats and species and contain nationally and internationally important populations of certain species such as the northern feather star, the burrowing sea anemone, the northern sea fan and cold water corals.
There is evidence that certain habitats have been affected, for example shallow and shelf subtidal sediments (including burrowed mud habitats). This stems largely from the effects of fishing over large areas of the seabed and more localised consequences from activities such as aquaculture.
The low abundance of some demersal commercial fish species across the west coast of Scotland is a major concern and is being addressed through various initiatives. Improved knowledge of fishing activity and its effect on the marine environment would be beneficial.
Establishment of new fisheries should only be undertaken following careful assessment of the viability and future sustainability of the fishery, especially given the sensitivity of some, particularly deep water, species to fishing and against a background of historic over-exploitation.
Sharks, skates and rays face further declines and are severely depleted all around the coast, although the number of sightings of basking sharks has increased in recent years, especially in the Minches and Malin Sea. These declines are largely the consequence of historically unsustainable catches in both target and non-target fisheries and their long-lived, very low fecundity life cycle. Many of these, for example, porbeagle and common skate, can no longer be targeted commercially.
Populations of some seabirds, harbour seals and some fish species have declined. Possible reasons include climate change, a number of different human activities and competition from other species. These declines may be associated with broader changes in the food web. For example, the decline in availability of sandeels has had a major influence on recent changes in seabird numbers on the east coast and in the Northern Isles.
Although, in general, the current assessment for cetaceans suggests there are no specific concerns, this has been made against a background of a very high level of uncertainty and little power to detect concerns if they currently exist.