What is Going on With British Oysters

The UK’s native oyster population has declined by over 95%! British Oysters are in trouble!

The decline of oysters in the UK has been a significant issue, with populations experiencing a staggering 95% decrease. Centuries of unsustainable fishing practices have played a major role in forcing British oyster populations into this steep decline. The European oyster, in particular, has been greatly affected. The decline can be attributed to overharvesting, habitat loss, pollution, and poor water quality12345. These factors have had a detrimental impact on oyster populations, leading to a significant decrease in their numbers. Efforts to restore oyster populations and address the causes of their decline are crucial for the future of these valuable marine creatures.

Why the decline in British oysters?

Unsustainable Fishing Practices

Centuries of unsustainable fishing practices have forced oyster populations into a steep decline, with the European oyster declining by around 95% 2. 

British Oysters have been historically over-harvested for centuries, leading to drastic declines in their populations24. This unsustainable fishing practice has put immense pressure on oyster stocks and hindered their ability to recover.

Disease

Along with the bad fishing practices, disease has affected our friendly bivalves as well. Diseases like norovirus and vibrio species. For those of you that don’t know what these are, here is a quick recap.

Norovirus is a foodborne virus that can cause illness in humans. There have been outbreaks of norovirus linked to the consumption of raw oysters in the UK.

Vibrio species: Vibrio species are bacteria that can cause disease in shellfish, including oysters. The increased prevalence of Vibrio species has been associated with the decline of native oyster populations.

Pollution

Pollution has been identified as one of the factors contributing to the decline of british oyster populations in the UK. Oysters are filter feeders, meaning they extract nutrients and particles from the surrounding water. If the water is polluted, oysters can accumulate toxins and pollutants, which can negatively impact their health and make them more vulnerable to diseases.

Pollution, such as chemical contaminants and excess nutrients from agricultural runoff or industrial activities, can weaken the immune systems of oysters, making them more susceptible to diseases. Pollution can introduce and facilitate the spread of pathogens that cause diseases in oysters. Contaminated water can harbor bacteria, viruses, and parasites that can infect oysters and lead to disease outbreaks. Pollution can also degrade the quality of oyster habitats, such as estuaries and coastal areas, by altering water chemistry, reducing oxygen levels, and damaging essential seafloor habitats. This can further stress oysters and make them more susceptible to diseases.

Efforts to reduce pollution and improve water quality are crucial for the recovery and conservation of oyster populations. By addressing pollution sources and implementing sustainable practices, it is possible to mitigate the impacts of pollution on oyster diseases and support the restoration of oyster populations.

Economic Impacts

1. Loss of oyster industry: Oysters have been an important part of the seafood industry, contributing millions of dollars to regional economies. The decline in oyster populations has led to a loss of jobs and economic activity associated with oyster harvesting, processing, and sales35.
2. Impact on water quality: Oysters are filter feeders and play a crucial role in improving water quality. They help to remove excess nutrients and sediment from the water, which can lead to improved clarity and overall ecosystem health. The decline in oyster populations can result in poorer water quality, affecting various industries such as tourism, fishing, and recreation that rely on clean and healthy water3.
3. Loss of associated species: Oyster beds provide important habitats for a diverse range of species. The decline in oyster populations can disrupt the ecological balance and lead to a loss of biodiversity. This can have cascading effects on other industries such as fisheries and ecotourism that depend on a healthy and diverse ecosystem4.
4. Increased prices: As oyster populations decline, the supply of oysters decreases. This can lead to increased prices for oysters, as demand may still remain high. Higher prices can impact consumers, restaurants, and other businesses that rely on affordable access to oysters15.
5. Reliance on imports: With the decline in local oyster populations, processors and consumers may increasingly rely on imported oysters to meet their needs. This can have economic implications, as local oyster industries may lose market share to imported oysters5.

Efforts are being made to restore British oyster populations and mitigate these economic impacts. Oyster restoration projects, habitat conservation, and sustainable fishing practices are being implemented to help revive oyster populations and support the associated industries46.

Efforts of Revival

There are efforts to restore British oyster populations, with a nearly £1.2 million project to recreate habitat for the shellfish around Scotland and the rest of the UK3. The species is of conservation concern due to historic declines, and not enough is known about wild populations of native oysters in the UK4. 

A major effort to bring back the UK’s native oysters is underway across England, Scotland, and Wales. In which thousands of the bivalves will be returned to coastal areas to improve water quality, create important habitats, and help rescue the species from the brink of extinction5. Despite their small size, oysters are capable of filtering 200 liters of water a day. These oysters will almost immediately begin their important work helping to create cleaner water5.

What they are doing about it…

Several measures are being taken to reduce pollution in areas where oysters are farmed in the UK. These measures include:

1. Managing agricultural pollution: Agricultural runoff is a significant source of pollution that can impact water quality and oyster health. Measures to limit agricultural pollution include managing field treatments, reducing diffuse runoff, and improving soil health2.
2. Reducing pollution from other forms of agriculture: Oyster farming produces few greenhouse gas emissions, making it a more environmentally friendly form of agriculture. By promoting oyster farming, it is possible to reduce pollution from other forms of agriculture3.
3. Environmental management plans: ASC certified oyster farms must minimize their impact on local ecosystems by implementing environmental management plans. Farms must ensure they are not adversely affecting the ecological integrity of the area in which they are located, and no harm to threatened or endangered species or their habitats is allowed5.
4. Managing organic deposits: ASC certified oyster farms are required to manage the organic deposits on the sediment beneath the farm in a responsible manner. Although no feed input is needed, so this is minimal5.

Efforts to reduce pollution are crucial for the recovery and conservation of oyster populations. By addressing pollution sources and implementing sustainable practices, it is possible to mitigate the impacts of pollution on oyster diseases and support the restoration of oyster populations1

Citations:
[1] https://www.zsl.org/news-and-events/news/million-pound-boost-britains-native-oyster-population
[2] https://www.ywt.org.uk/give-seas-a-chance/oysters
[3] https://www.scotsman.com/news/environment/million-pound-project-to-restore-oyster-population-in-scotland-and-rest-of-uk-2933234
[4] https://www.mcsuk.org/goodfishguide/ratings/wild-capture/469/
[5] https://www.independent.co.uk/news/uk/home-news/oysters-rewilding-water-quality-sunderland-b1822487.html
[6] https://www.discoverwildlife.com/animal-facts/insects-invertebrates/facts-about-european-native-oysters/