Aquaculture for all

Oyster Production Within The Multiple Uses Of Estuaries

Environment Oysters +1 more

Sophie Hockley, University College, London discusses oyster production within the multiple uses of estuaries as part of her fieldwork research for an MSc dissertation.

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The decline in native oysters around the coast of the UK and worldwide has been well documented. This species has both economic and ecological value and its decline has triggered attempts to conserve remaining wild fisheries, and has led to a growth in oyster aquaculture.

Nevertheless, although studies have shown that restoration of the native oyster would be feasible, there are few restoration projects underway. One area that is renowned for its oysters is the Fal estuary in Cornwall. It is part of a Special Area of Conservation (SAC) that includes the neighbouring Helford estuary. As well as being home to one of the remaining native oyster fisheries in the UK, oyster aquaculture also takes place here. But these are just two of the uses in this multiple use SAC, and attempts to restore the native fishery or expand aquaculture are likely to have an impact on other uses of the estuaries (just as other uses can affect oyster production).

Because oyster fishing and aquaculture rarely exist in isolation, a short project was undertaken in this location to research issues related to the multiple uses of estuaries, which gives an insight into some of the factors that might hinder restoration efforts.

The management of estuaries The global decline in oyster populations has taken place alongside a more general decline in coastal and marine ecosystems.

Estuary management is therefore increasingly influenced by conservation objectives, as seen in the designation of Special Areas of Conservation. The Fal and Helford SAC was created because of its significant habitat features including saltmarshes, intertidal mudflats and large shallow inlets and bays.

Two sub-features are the maerl and eelgrass beds (maerl is a rare form of algae; both living and dead maerl and eelgrass provide important habitats for many other species).

The management forum is comprised of the relevant authorities, and the advisory group is for all stakeholders who have an interest in this area. The goal is to maintain current conditions; therefore each relevant authority must work in a way that does not adversely affect the features of the SAC.

Oyster fishing and farming

The native oyster fishery on the Fal continues to be worked under sail because byelaws prohibit motors. As such it is also of cultural and historical interest: The working boats out on the Carrick Roads and associated events such as the oyster festival make up a part of the fishing heritage of this area. Last season there were ten or so sail boats at work. In the past there have been over 70, but numbers vary according to the state of the fishery.

As a wild resource, fluctuations in catch are expected. Unpredictability comes from within but also increasingly from outside of the fishery. When discussing its future, frequent comments are made about “the last of the oysters” and “the last of the boats”.

Whilst it is said that these sentiments have been repeated for many years, this fishery suffers from many of the problems that are affecting native oysters elsewhere: There has been low spatfall for several years, a new strain of bonamia was found in 2011, and there is an increase in slipper limpets and invasive red weed.

There are also concerns about: the possible introduction of licences from the EU for fishing boats without motors; plans for capital dredging at Falmouth; the trend to buy up working boats for competitive racing; and the lack of consultation about estuary management decisions.

Aquaculture takes place in the Helford estuary, where Pacific oysters are cultivated in an area that is held in private tenure. There are advantages and difficulties in practicing aquaculture in a conservation area: Both conservationists and oyster farmers promote water quality and a healthy marine environment but operating in a Special Area of Conservation adds to the complexity of running such a business. The techniques that are used (bags and racks or cages, quarterly surveys to check that the Pacific oysters are not settling in the area, the use of triploids that are bred to be less fertile that the normal diploids) aim to minimise the impacts of farming and to maximise growth.

Multiple uses of estuaries

The native oyster fishery is an example of a small industry competing for space within the estuary. Some of the multiple uses are: fishing and angling; commerce; recreation (water sports, coastal walking, diving etc.); wildlife watching; education; transport and tourism. Multiple uses compete to varying extents but, because of the legal framework of the SAC, it is conservation that overshadows all other uses.

Native oysters are not a feature of the SAC and they are therefore not considered a conservation priority. But this fishery might benefit indirectly from the conservation opposition to the plans for the capital dredge, which is part of the Port of Falmouth Development Initiative.

The application for a dredging licence has been rejected by the Marine Management Organisation as the plans were deemed likely to have an adverse affect on the SAC (primarily because dredging could damage or destroy maerl beds, this site being one of only a few places in the UK where they are found). This is currently being challenged on the grounds that there are imperative reasons of overriding public interest, known as an IROPI case, for the work to go ahead.

There is a lot of local support for the docks and the dredging plans, but many in the fishing industry are concerned about tri-butyl tin (TBT) and other toxic materials being stirred up during this work. Currently the main issue in the Fal & Helford is this conflict between conservation and development. Technology can reduce the impacts of development (such as mitigation measures for the dredging work) but disturbance to the marine environment remains a concern.

Other areas of conflict between conservation, commercial development and fishing also exist. For example, scallop dredging has been banned within the SAC on conservation grounds. The mooring of foreign cargo vessels is a source of income for ports, but monitoring has indicated that invasive species are brought in on their hulls and in ballast water. The anchoring of ships in the bay for bunkering has affected fishermen by taking out pots and lines and reducing the area in which they can work.

Stakeholder participation

Participation in decision-making and communication between users would appear to be both desirable and necessary in an estuary system whose resources are used in different ways and at different scales by an ever increasing number of people.

Despite the potential advantages in terms of better stakeholder engagement, putting measures in place to promote meaningful participation is seen as a luxury that the relevant authorities cannot afford. Many estuary users and local residents know very little about the Special Area of Conservation and people often remain unaware of its existence until they are told they cannot do something, when it is introduced in a negative light. Thus increasing public awareness should be an important goal, both to protect this area and to boost public involvement.

The designation of this SAC has changed the context in which the multiple uses exist, and has brought conservation to the forefront of the management of the estuaries. But conservation has also alienated some estuary users, and it could be argued that it has become an additional form of bureaucracy. Participation could therefore be regarded as an opportunity to create a more effective and meaningful conservation programme that takes into account the needs of different user groups, and creates a balance between conservation and development.

December 2011