Mussel power: the fight to save Strangford's rare reef
Horse mussels are arguably the greatest unsung heroes of the UK's coast.
The habitats that mussel reefs create support hundreds of diverse and sometimes unique species, as well as providing a livelihood for fishermen.
Strangford Lough, Northern Ireland is home to one of these reefs but extensive damage in recent decades has left it in a precarious position.
Can conservationists and the people that rely on this natural resource work together to ensure it survives?
Summer of Wildlife event at Castle Ward on September 15
Horse mussels (Modiolus modiolus) are relatively common throughout UK waters, but the habitat these mussels help to form at Strangford Lough is incredibly rare.
Strangford Lough has been designated an area of special scientific interest (ASSI), a special area of conservation (SAC) and is one of only three marine nature reserves in the UK.
"A lot of species depend on the reef, so it's important to protect it," said Dr Jade Berman, a marine biologist at the Ulster Wildlife Trust.
"We've got species that are unique to Strangford that depend on the horse mussel reef,"
Threat and decline
The rich diversity of life at Strangford means historically it has also been an important area for local fisherman.
However, commercial fishing in the 1980s and 1990s using trawlers that drag fishing equipment - 'mobile gear' - across the sea bed were blamed for the sharp decline of the reef.
It has been argued by local conservationists that trawling was akin to putting a bulldozer through an oak wood.
"In that respect, I think it's only right to take a precautionary approach to a special area of conservation," said Joe Breen, a marine conservation officer with the Northern Ireland Environment Agency.
But the theory that this fishing method is to blame hasn't received universal support in the Strangford area.
"There are places... like Greenisland passage, where there was never a trawler or a dredger," said Dick James, a representative of the Northern Ireland Fish Producers Organisation.
"It used to be populated with Modiolus from bank to bank but now isn't, so there are some other reasons for the decline, not just fishing.
"The fishermen have been made pariahs and are blamed for something which it's highly unlikely they've caused," Mr James added.
The Ulster Wildlife Trust, however, believes that commercial fishing of this kind may have contributed to the destruction of the reef, as Dr Berman explained:
"That's the crux of the European complaint [to the European Commission] which has been upheld. Trawling wouldn't have helped certainly and there are studies that back this up."
Man versus nature
After lobbying the UK government for over two decades on the issue, the Ulster Wildlife Trust made a complaint to the European Commission in 2003 citing a lack of protection for the reef.
The Northern Ireland government was threatened with hefty fines of £8 million and in 2005 drew up measures to give greater protection to the mussel reef in Strangford Lough.
Meet the mussel
- Horse mussels are edible but are not eaten due to their taste
- They provide important ecosystem services such as shelter for young fish and water filtration - One mussel can filter about one litre of water per hour
- Although their size is variable, they are commonly between 50 and 100 mm in length
- Modiolus modiolus horse mussels usually live for at least 25 years but some survive for up to 50 years
The Ulster Wildlife Trust launched a second complaint in 2011 because it felt not enough progress was being made with implementation.
A ban on all commercial fishing with 'mobile gear' in the lough is one of the measures proposed to protect the reef.
However, exclusion zones where pot fishing is also prohibited have led to complaints from local fishermen, who say that 'static' pot fishing should be exempt from the ban.
"We're very disappointed that they've seen fit to impose an exclusion zone to a type of fishing gear which is benign in the environment," said Mr James.
"The science says there's no reason to not continue fishing there. The effect will be - and it's already happening - that some fishermen will have to pack up."
Dr Berman said the state of the reef is "so fragile" that pot fishing needs to be banned as a precautionary measure:
"Most of them [fishermen] understand what we're trying to do and they want to ensure that fishing is sustainable in the future too," said Dr Berman.
"Pot fishers share the same objectives as us [at the Ulster Wildlife Trust]. We want them to be given a pot fishing management strategy and we want sustainable fisheries."
A restoration plan has been developed jointly by the Department of the Environment and the Department of Agriculture and Rural Development. A Modiolus Restoration Steering Group, which includes representatives from both conservation and fishing communities as well as academics from Queen's University, Belfast will help to oversee the plan.
This may include the creation of artificial reefs within the waters around the lough. These have the potential to develop aquatic plants and animals similar to the natural reef and in turn, serve as a reservoir of appropriate species to colonise the recovering natural reefs.
The hope is that an abundance of horse mussel reef will also eventually increase the presence of commercial fish stocks in Strangford Lough.
It is estimated that full restoration of the reef could take up to 30 years, which could lead to friction between fishermen, conservationists and government departments in the future.
Whether the recovery is strong enough or fast enough to please everyone at Strangford remains to be seen.
The wildlife of Strangford Lough features on Wild on Water which begins on BBC One (Northern Ireland), Wednesday 11 September at 1930 BST.