The UK’s first State of Nature report, which has been launched by Sir David Attenborough, reveals that 60% of UK wildlife species are in decline. And that is just the species which have been well studied. Our ability to monitor the state of nature, and respond with appropriate conservation action, is hampered by a lack of knowledge on trends for most of the 8,500 marine species.
The UK’s marine area covers over 850000 km2: that’s three times more than her land area. Her seas regularly host 13 species of marine mammal and even leatherback turtles. When divers first visit UK seas they are often amazed at the diversity and abundance of life (although, in winter, they are sometimes also dismayed by the cold water).
Despite its importance for wildlife, our knowledge of the state of our seas is poor. This lack of knowledge hampers our ability to assess the impact of man’s activities. Species commercially fished are the best known. The state of UK fish stocks has improved recently but overall 75% of EU fish populations continue to be overfished. Skates and rays are no longer viable commercial species in many areas.
Since 1996, harbour seals have declined by 31% in Scottish waters, particularly around Orkney (which showed a 66% decline) and northern Scotland, due to a combination of factors including pollution, disease, prey availability and competition with grey seals. From the 1950s to the 1990s, grey seal pup production increased consistently, but it is no longer increasing in some regions.
There is evidence that sub-tidal marine sediment habitats have been damaged over large areas by fishing activity, in particular by bottom-trawl and scallop dredge gear. Such activities can have huge impacts on bottom-dwellers such as the ocean quahog, a remarkable bivalve mollusc that can live for 500 years! At a more local scale, these activities also damage sensitive features, such as maerl beds and seagrass, that shelter a range of wildlife.
Sharks, skates and rays face continuing declines and are severely depleted all around the Scottish coast, in part due to overfishing. Elsewhere, most commercial fish stocks around the UK remain depleted, though there have been improvements in stocks of certain species in the last 5–10 years.
Historically, however, national and international fish landings are a fraction of the highs in the 1960s and 1970s, and generally smaller than in the early 20th century. The problems of overfishing and discards are being discussed as part of the reform of the EU Common Fisheries Policy.
The continuous plankton recorder has been monitoring plankton in UK waters since 1931. These small plants and animals form the base of our marine food webs and play a pivotal role in the ecosystem by regulating larval fish stocks. Since 1950, there have been substantial changes to the main animal group within the plankton – copepods.
The total abundance of copepods has declined markedly, and the species present are changing as the sea warms. Already, these changes are negatively affecting fish species, such as cod, as well as seabirds.
At a smaller scale, there are almost no areas of pristine marine biodiversity left around the UK, as a result of increasingly intensive human pressures. Not only are fewer fish caught today compared with 20th century baselines, but they are also significantly smaller and they mature at a younger age. This is because the relative abundance of small and early maturing species increases as a result of overfishing.
Plastic pollution is a persistent problem in all areas. There have been significant recent improvements in water quality, however, due to the treatment of land-based discharges and international laws on marine pollution from ships.
Heads of leading UK conservation organisations are putting their names to a letter calling on David Cameron to act now for nature.
The State of Nature in the UK and its Overseas Territories RSPB 2013