Aquaculture

Filter-feeding bivalves (clams, mussels, scallops and oysters) make up approximately one-quarter of the world's aquaculture production. China is the top producer, responsible for slightly more than 80 percent of the world’s farmed bivalve shellfish. Other important bivalve shellfish producing regions include Japan, the United States, France, Thailand, Spain, New Zealand and Italy.

Unlike most fin fish and crustaceans, filter-feeding bivalves feed on naturally occurring phytoplankton at the base of the food chain. This eliminates the need for external feed inputs. Also, these shellfish often improve water quality by filtering sediment and excess nutrients. Shellfish gear and culture practices can influence the diversity and abundance of fish and invertebrates in surrounding waters and benthic substrates. The complex three-dimensional habitat created by shellfish can be beneficial because it often is colonized by a diversity of vertebrate and invertebrate fauna. A more indirect environmental benefit is that, because this type of seafood depends on clean water, coastal communities that farm bivalve shellfish are highly committed to protecting water quality. This often helps create the political will needed to improve sewage treatment plants and local septic systems.

Regardless of these benefits, this type of aquaculture is not without its challenges, as explained in the issues section below.

Main issues of bivalve aquaculture

The key environmental and social issues related to bivalve production are:

Ecosystem integrity: Habitat interactions and ecological community structure modifications
Genetics: Gene transfer to wild populations, inbreeding, and escapes
Biosecurity: Deliberate or inadvertent introduction of new exotic species, pests, and pathogens
Disease and pest management: Transfer of disease and pests to and from the wild, within the wild, and within aquaculture systems; loading of pathogens; and the use of chemicals for preventing and controlling diseases and pests
Farm maintenance: Management and disposal of debris (e.g., nets and bags), chemicals, and organic waste; processing of wastes; treatment of effluent; and maintenance of equipment
Multi-user cooperation: Location, development, and aesthetics of aquaculture sites; and public access to aquaculture sites

Our solution

These issues were addressed through the Bivalve Aquaculture Dialogue, a multi-stakeholder process that began in 2007 and ended in August 2010. The goal of the Dialogue was to develop measurable, performance-based, global standards that will help minimize the key environmental and social impacts associated with the farming of clams, oysters, scallops and mussels. The Dialogue included more than 300 farmers, nongovernmental organization representatives, researchers and others. WWF coordinated the Dialogue and the Global Steering Committee managed the process. Read more about the goals and objectives for the Dialogue.

Click here to download the standards and press release.

The standards will be given to a new organization, called the Aquaculture Stewardship Council (ASC), that will be responsible for working with independent, third party entities to certify farms that are in compliance with the standards. 

Principles

Dialogue participants identified the following principles -- high level goals -- for addressing the environmental and social issues associated with bivalve aquaculture. The principles provided the framework for developing the criteria, indicators and standards for responsible bivalve farming. The criteria aim to provide direction on how to reduce each impact and the indicators address how to measure the extent of each impact. The standards are quantitative performance levels that evaluate whether a principle is achieved.

1. Obey the law and comply with all applicable legal requirements and regulations
2. Avoid, remedy or mitigate significant adverse effects on habitats, biodiversity, and ecological processes
3. Avoid adverse effects on the health and genetic diversity of wild populations
4. Manage disease and pests in an environmentally responsible manner
5. Use resources efficiently
6. Be a good neighbor and conscientious coastal citizen
7. Develop and operate farms in a socially and culturally responsible manner

Learn more

• Bivalve Dialogue process guidance document
  English | Spanish | French | Chinese
• Bivalve Dialogue meeting reports and presentations
• List of bivalve Dialogue Global Steering Committee members and regional advisors
• Bivalve Dialogue fact sheet
  English | Spanish
• Fact sheet about what to look for when buying oysters
• Research papers, journal articles and reports about bivalve aquaculture's interaction with the environment
• Bivalve Dialogue work program

Read more about the other aquaculture Dialogues WWF is working on