The Irish Sea region extends from the Mull of Kintyre in the north to St George’s Channel in the south and includes the Firth of Clyde. Water depths are mostly less than 50 m but reach 100 m in the deeper western areas, which become stratified in the summer. The coastline is mostly rocky but with some extensive areas of intertidal sediment such as Morecambe Bay and the Solway Firth. The main offshore habitats are sands and gravels but mud is a feature in some areas. There are large seasonal variations in sea-surface temperature, ranging from 4 °C in winter to 18 °C in summer. Eastern areas receive significant freshwater input from the rivers of north-west England and south-west Scotland, noticeably lowering the salinity along the coastline.

Climate change

Sea level is rising and increasing the risk of coastal erosion and flooding. This is particularly important for the low-lying areas in the north-west of England, north Wales and south-west Scotland. Sea temperature is rising and has caused a change in seabed biological communities in the eastern Irish Sea. For example, it has caused a decline in coldwater native seaweeds and has contributed to the spread of non-native species such as barnacle, wire weed and the Pacific oyster. On a positive note, the honey-comb worm has re-established on the north Wales coast, possibly due to the warming waters.

Maritime economy

The region is one of the busiest in the UK, has the major cities of Merseyside and Greater Manchester, Strathclyde and Belfast on its shores and is an important focus for a diverse array of activities. Pilot studies for marine planning have been conducted in this region.

Oil and gas is a key industry with a few discrete but productive reserves. In addition, there are important gas pipeline links from England and Scotland to Northern Ireland, the Republic of Ireland and the Isle of Man. The region has among the best sources of wind energy in the UK. There are four wind farms operating (North Hoyle, Burbo Bank, Barrow, Robin Rigg) and more are proposed. There are also important power and telecommunication links between mainland UK and Northern Ireland, the Republic of Ireland and the Isle of Man. Due to a number of strategically important coastal power stations, the value of water abstraction for cooling water is significant. The Sellafield nuclear fuel reprocessing facility is located in the region.

The largest and most valuable fishery in the Irish Sea is for Nephrops with a number of smaller fin-fish and shellfish fisheries. The Irish Sea is a nationally important area for shellfisheries. Species farmed are mainly mussels in Northern Ireland and the Menai Straits in Wales and oysters and scallops in the southern part of Strathclyde.

Maritime transport activities mainly comprise freight traffic between the surrounding countries. 21% of disposal sites for dredged material in the UK are located here but not all are in use at any one time.

This region has the second highest investment in coastal and flood protection. There are long stretches of attractive coast within easy reach of the population, making recreation important. Activities include surfing (e.g. along the Lleyn Peninsula), scuba diving (e.g. Strangford Lough and Anglesey) and cetacean watching (e.g. Cardigan Bay).

Fishing pressure

Assessed commercial fish stocks, including stocks of cod and sole, are neither at full reproductive capacity nor being harvested sustainably, with the exception of plaice stocks. However, the state of the demersal fish community as a whole is improving shown by evidence of increasing abundance, biomass, productivity and size composition. Populations of some species including cod, flounder and angel shark are not improving and smaller fish now dominate. Some rivers do not support the migration of salmon.

Coastal and seabed habitats, particularly soft sediments, are affected by bottom trawling and rocky coastlines are affected by shellfish collecting.

Other issues affecting status

Seabird populations are doing well: breeding numbers have increased substantially over the past 21 years. The number of waterbirds, such as waders, has decreased as more are now wintering in east coast estuaries.

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