By Will Bevan
In my last blog post for UK Youth for Nature’s oceans campaign, I looked at how our coasts are crucial in supporting a huge diversity of bird species all year round. This time I’ll be travelling further out into our territorial waters, to see how the fate of the seabirds which call our shores home are inextricably tied to the health of our oceans.
What do we mean by territorial waters?
The term ‘territorial waters’ is often used as a broad term to encompass the seas which are under the jurisdiction of a government. This includes the territorial sea, which extends 12 nautical miles from the coastline, and the Exclusive Economic Zone, which extends a further 200 nautical miles out – unless there is another country within these limits. In the UK’s territorial waters, the government has control over all economic activity including fishing, mining, and energy production. It also has a responsibility to protect the incredibly diverse wildlife which calls these waters home, to make sure that we are surrounded by thriving, healthy seas.
It might surprise you to find out that the UK has the fifth largest Exclusive Economic Zone in the world, as it is responsible for the waters surrounding its overseas territories as well. This includes such far flung places as South Georgia and the South Sandwich Islands, Saint Helena, Gough Island, Tristan de Cunha, and the Pitcairn Islands. These overseas territories hugely increase the UK’s influence over the oceans, as well as the wildlife it is responsible for – a responsibility which is shared with the local governments of these territories. This also vastly increases the number of seabird species which occur in waters under UK jurisdiction, giving us an even greater role on the world stage in protecting them. For example, these territories are home to a quarter of the world’s penguins and a third of the world’s breeding albatrosses!
Why are our territorial waters important for seabirds?
Most seabirds are hugely dependent on the ocean as a source of food and are drawn to ‘hotspots’ of high productivity where prey is more abundant. These ‘hotspots’ are especially important during the breeding season, as seabirds need to have plenty of nutritious food within close range of their colonies so that they can provide enough for their hungry, growing chicks. The distances and locations they travel to find food will vary depending on the species, and even between individual birds, but seabirds must be able to balance feeding their chicks with their own energy needs. If they cannot, the adults must prioritise their own survival over that of their chicks, opting to try again the next year. Therefore seabirds thrive and successfully raise chicks in colonies where they can access abundant, reliable sources of food that they can travel to without exhausting themselves completely. The seas around the UK are highly productive, and this combined with the wide range of suitable habitats along our coastlines support the huge numbers and diversity of seabirds which live here. This is also true for UK overseas territories, with places like Gough Island supporting large colonies of breeding seabirds, including endangered sooty albatrosses, Atlantic yellow-nosed albatrosses, and the critically endangered Tristan albatross.
The availability of prey can be influenced by numerous factors which often interact in complex ways, such as ocean temperature, ocean currents, the topography of the seabed, and the time of year. Seabirds must time their breeding efforts for when conditions are just right and there will be plenty of food to raise their young. This means that their populations are highly sensitive to any changes in the marine environment that might affect how much prey there is, where it will be, and when it is around.
Our territorial waters are not just important during the breeding season, with some seabirds staying through the winter months whilst others disperse out into the open ocean or migrate to other shores. The birds that stay need to be able to find food to sustain them through the cold winter months, and whilst they are not tied to feeding their chicks at the colonies, stormy weather can rapidly deplete energy supplies and affect their ability to feed, with exhausted birds dying from hunger and exposure. These seabird ‘wrecks’ can be particularly bad in some years, such as in 2014, when thousands of dead birds washed up on our shores. Bad weather in winter can also have knock on effects in the breeding season, with storms in late winter and early spring influencing the ability of seabirds to get in prime condition for courtship and the demands of raising young.
Threats in our waters
What is clear is that seabirds require healthy, biodiverse, and productive oceans in order to give them the best chance of breeding and surviving all year round, and we therefore have a responsibility to ensure that this is the case where we have jurisdiction. However, some of our internationally important populations of seabirds, such as northern fulmars, European shags, Arctic skuas, and black-legged kittiwakes are declining alarmingly.For other species the picture is mixed, with Atlantic puffins doing poorly in places like Shetland and the Isle of May in the Northeast but faring better at Skomer and Skokholm Islands in Wales. Whilst the causes are often unclear as to exactly why these trends are occurring, with complex interactions between multiple stressors, we can identify some key factors in these declines:
Climate change
Warming oceans are affecting the availability of some prey species, such as sandeels, which are heavily relied on by birds like puffins and kittiwakes during the breeding season as a source of plentiful, nutritious food. Climate change is also increasing the incidence of severe storms, resulting in more seabird ‘wrecks’. The European shag is suffering this fate, being a coastal species which does not venture far from its colonies and having plumage which is not as waterproof as other seabirds it finds it difficult to escape bad weather and is therefore more susceptible to death by exposure. Climate change is going to be difficult to deal with, but the best way to ensure resilience against it is to deal effectively with other threats, such as overfishing, which are easier to deal with.
Overfishing
Commercial fisheries, especially those which target specific species, can be devastating for seabird populations which rely on these species. For example, in Scotland, commercial sandeel fisheries were found to be creating food shortages for kittiwakes by depriving them of this crucial resource during the breeding season. In this case, a seasonal ban was introduced on fishing during this time, demonstrating that we can act accordingly when we understand the causes of declines, although food shortages are still an issue as a result of climate change. Overfishing is also thought to have contributed to the decline of naturally nesting populations of Herring gulls, combined with changes in fisheries practices such as a reduction in discards, and this species has started to find more reliable food sources in our towns and cities. Over exploitation of fisheries is also happening in overseas territories, with populations of sooty terns on Ascension Island plummeting as a result.
We can deal with overfishing and other damaging economic activities by introducing bans and limits at certain times or year or by creating Marine Protected Areas (MPA’s). However, whilst nearly a quarter of the territorial waters around the UK are designated MPA’s, this is often in name only, with harmful activities such as fishing, bottom trawling and dredging still allowed. We therefore need immediate strengthening of these protections.
Fisheries bycatch
Like many other marine animals, such as dolphins, sharks, and turtles, seabirds can end up being killed unintentionally by fishing vessels. Birds such as albatrosses are particularly vulnerable, getting caught on the baited hooks of longline fishing vessels and being dragged underwater, for example. Whilst progress is being made in reducing bycatch by developing new technologies, increased monitoring, and education, dealing with this problem requires international cooperation as these species often roam large distances through the territorial waters of multiple nations.
Invasive species
Though not strictly a marine problem, invasive alien species such as mice, rats, and cats are a massive problem for seabirds, with chicks and incubating birds often helpless against predation, and they can decimate populations on some islands. Removal of invasive species will be one of the most effective ways to prevent seabird declines across many colonies, with restoration projects such as the one currently being undertaken on Gough Island hopefully improving their prospects. On Lundy Island in the Bristol Channel, rats were eradicated in 2006, and since then the seabird population has more than trebled, proving the effectiveness of dealing with this threat.
Pollution
Oil pollution can ruin the waterproofing of seabirds feathers, affecting feeding and thermoregulation and eventually resulting in death by exposure. Plastic pollution is a growing menace, within many species consuming large amounts of plastic and feeding it to their chicks. To them, as well as looking like food, plastic can also even smell like food, picking up a compound called dimethyl sulphide which is usually given off by some microorganisms when they break down, such as when they are being eaten. The seabirds can use this smell to detect prey which are eating the microorganisms, an amazing instinct which is unfortunately resulting in many deaths when birds eat the wrong things. Whilst plastic pollution is not a major cause of population declines at the moment, more and more plastic enters the oceans every day and production keeps increasing, and so it is vital to curb this threat now.
Next time, join me for the final part of this series, where I will be looking at the ‘High Seas’, the oceans beyond national jurisdiction which cover around 50% of the planet! Here there is often a crucial lack of protection for seabirds, with some species spending a large proportion of their time in these waters. The threats I touched on in this article are often much worse in the high seas, where there is usually no oversight, monitoring, or legal protection. I’ll be looking in depth at this overlooked part of our oceans and show that in order to halt drastic seabird declines, the UK needs to be a key player in the upcoming negotiations for a ‘High Seas Treaty’, which will ensure a legally binding commitment to conservation and sustainable development in areas beyond national jurisdiction.
