Oysters

Governance

Governance systems play an important part in ensuring environmental sustainability, and whilst these have evolved rapidly with the growth of the industry, there are differences between regions and countries. Poor governance can result in industry stagnation, the spread of preventable diseases, environmental damage and opposition to aquaculture activities by local communities and groups such as non-governmental organisations (NGOs). Key governance responsibilities are ensuring environmental assessment and decision making processes are in place for sensitive and coastal ecosystems, which help deliver sustainable aquaculture whilst managing possible adverse impacts. Other regulatory and governance aspects should cover aspects such as water abstraction and discharge, health monitoring, and so forth.

Four principles – accountability, effectiveness and efficiency of governments, equity, and predictability of the rule of law – are necessary for effective aquaculture governance. These principles should guide the administration, legislative and regulatory framework of aquaculture. In addition to governments, other stakeholders such as communities, non-governmental organisations (NGOs) and producers should also be involved in the governance of the industry¹.

The vast majority of oyster production is undertaken in three global regions: Asia-Pacific, North America, and Europe.

Asia-Pacific²

While many countries in Asia-Pacific have made commendable efforts to set up policies, administrative, legal and regulatory frameworks to properly develop and manage aquaculture, some countries in the region are still lagging behind.  However, many Asia-Pacific regional countries (e.g. Australia, NZ) enjoy established strong aquaculture governance structures (policies, institutions, regulations, etc.) in support of sustainable development and management of aquaculture at all levels.

North America³

National and provincial/state governments in both Canada and the US have strategies for the development of aquaculture, and governance systems are highly evolved. The thrust of aquaculture development in Canada is focused on environmental sustainability. In the US, development is also geared toward sustainability with offshore expansion.

Europe⁴

With the notable exceptions of the major European aquaculture producers Norway, Russia and Turkey, the shaping of regulations and the instruments for development and investment in European aquaculture falls under the European Union (EU), and are highly evolved. The principal frameworks for EU aquaculture is the Common Fisheries Policy (CFP) as well as the EU Blue Growth Strategy, intended to stimulate and guide aquaculture development in Europe which is environmentally, socially and economically sustainable. In non-EU member states there are largely equivalent policies.

Outlook
Although there has been criticism surrounding bivalve/oyster aquaculture⁵, generally the impacts of oyster farming are seen as low and relatively benign^{6, 7, 8}. Impacts can include: seabed deposition of solid wastes such as pseudofeces; changes to biodiversity; the depletion of phytoplankton for other species to eat; and the reduction of light reaching the sea bed. The positive impacts and benefits that bivalve/oyster aquaculture can have on marine ecosystems, include:

• Buffering of estuaries and coastal ocean waters against excessive phytoplankton blooms
• Removal of inorganic sediments from suspension, e.g. interest in harnessing bivalve/oyster culture to help clean coastal waters (i.e. bioremediation) has increased in recent years^{9, 10}
• Counteracting water turbidity and an increase in water clarity leading to greater light levels
• Enhancement of water clarity can increase growth of sea grasses
• Creation of structural habitat by shellfish beds and reefs can be important for biodiversity and as nurseries for fish, crustaceans and other molluscs
• Increased food availability for birds
• Carbon sequestration through shell formation

Feed is generally perceived to be one of the major risk factors in aquaculture production of fish and crustacea. However oysters consume food that occurs naturally in the environment and are not supplied with commercial aquafeeds; also they are not treated with chemicals or veterinary medicines unlike in other forms of aquaculture. Excluding seaweeds, one-third of all farmed seafood, some 20 million tonnes annually, is produced without additional feeding. The most important non-fed animal species, apart from bivalve molluscs (mainly clams, oysters, mussels and scallops), include two finfish species (silver carp and bighead carp), as well as other filter feeding animals such as sea squirts¹¹.

These positive, natural and ‘ecosystem service’ aspects of bivalve aquaculture in general are increasingly being seen as major factors to promote their culture as the most environmentally sustainable type of seafood production¹¹. As such, increased mussel aquaculture is anticipated, including the potential for increased production in the UK¹². The Seafood 2040 Strategy for instance, highlights bivalve aquaculture as an opportunity to generate sustainable protein for domestic consumption or export, provide employment in fragile coastal communities, whilst offering significant ecosystem services¹³.

As bivalves are farmed in open marine environments, and because there are no treatment or vaccination options, disease prevention is essential. Work continues to improve understanding of bivalve diseases and develop innovative solutions and tools for their management and prevention^{14, 15}.