Ecosystem overviews

Celtic Seas Ecosystem Overview

Key signals

Fishing accounts for several of the main pressures in the Celtic Seas ecoregion, e.g. species extraction and physical seabed disturbance, which affects mostly fish, cephalopods, and benthic habitats and associated biota.
Extraction of commercial demersal, benthic, and shellfish stocks in the ecoregion has decreased since its peak in the late 1990s and is on average approaching sustainable levels for the assessed stocks in each of these groups.
Temperature related distributional changes have been observed for a number of fish species within the region.
Physical seabed disturbance by mobile bottom‑contacting fishing gear decreased by 35% from 2003 to 2014.
Small-scale coastal fisheries contribute less than 10% of total fish landings but have regional importance in terms of employment (22% FTE) and revenue (14%).
Surface water temperature in shallow shelf regions are warming and becoming seasonally increasingly stratified and nutrient limited in some areas. Freshening of western subpolar north Atlantic waters is observed in deeper areas of the ecoregion such as the Rockall Trough and the Faroe-Shetland Channel.
A decline of 50% in summer copepod abundance has been observed over the last 60 years due to earlier spring blooms and/or the increased contribution of picophytoplankton to the overall phytoplankton abundance.
Long-term coastal dinoflagellate abundance showed a weak decrease from 1993–2019 at the west coast observatory and an increase compared to diatoms in other inshore areas in 2006–2015. This may have implications for the frequency and intensity of harmful algal bloom events (HABs), which have caused widespread closures of shellfish farming areas and occasional mortalities of benthic organisms as well as farmed and wild fish.
The abundance of breeding seabirds has shown a downward trend since the early 2000s.