Shrimp Farms: Environmental Impact And Pollution Concerns

Shrimp farms have been associated with a range of environmental issues, including water pollution, chemical and antibiotic use, and deforestation. With shrimp farming contributing to 55% of global shrimp production, the industry's environmental impact is significant. The pollution created by shrimp farms can include shrimp feces, uneaten food, pesticides, and antibiotics, which can contaminate nearby bodies of water and lead to algal blooms and the production of harmful toxins. Additionally, the use of antibiotics in shrimp farming can contribute to the emergence of antibiotic-resistant bacteria, potentially affecting humans and other animals. Furthermore, shrimp farms have been linked to mangrove deforestation, causing significant carbon losses and threatening local ecosystems. As the sector continues to expand, there is a growing need to address these environmental challenges and adopt more sustainable practices.

Mangrove deforestation

Mangrove forests are intricate networks that bridge the gap between land and sea, found along two-thirds of the planet's tropical coastlines. They are home to many rare, threatened, and iconic species, as well as millions of people who depend on coastal ecosystems for food and livelihoods. Mangroves also provide a vital defence against floods and storms and play a crucial role in sequestering carbon from the atmosphere.

Despite their importance, mangroves are still being converted for food production, including shrimp farming. Between 8% and 10.5% of the total shrimp pond area is from mangrove deforestation. In the 1970s, 80s, and 90s, the world lost about 20% of its mangrove forests, with high rates of land conversion for shrimp farming accounting for 30-50% of this loss. During this period, shrimp farming may have resulted in an estimated 238,319 hectares of mangroves lost in key producing countries.

Shrimp farms are frequently built on the site of mangrove forests, which are cut down to make way for ponds, causing significant carbon losses. The carbon intensity of shrimp farming from deforested mangroves is estimated to be 10 times greater than that of beef grown in deforested Amazonian rainforest.

However, there are efforts to mitigate the impact of shrimp farming on mangroves. The Aquaculture Stewardship Council (ASC), for example, has set rigorous standards that prohibit the conversion of mangroves and other intact habitats. Some companies, like Selva Shrimp in Indonesia, are piloting projects that aim to demonstrate the financial sustainability of conscious shrimp production, with additional revenues being put back into restoring the area's coastal mangrove forests.

While shrimp farming has had a negative impact on mangroves in the past, there is hope that with better practices and more sustainable farming methods, the industry can reduce its environmental footprint and help restore these critical ecosystems.

Antibiotic use

Antibiotics are commonly used in shrimp farming to prevent or treat disease outbreaks. This is due to the high density at which shrimps are cultivated, which makes the prevalence of pathogens one of the biggest challenges faced by the aquaculture industry. Infections caused by pathogens can lead to massive production loss, which can completely wipe out shrimp farms. For example, a post-larvae infection caused by bacterial pathogens in shrimps in 2013 resulted in 1 billion dollars in production loss.

However, the use of antibiotics in shrimp farming can lead to the development of antibiotic resistance among pathogens infecting cultured animals and humans. This is a recent issue that has not been thoroughly investigated. There is also limited knowledge about the environmental effects of antibiotic use in aquaculture.

A study conducted in 2000 found that a large proportion of shrimp farmers along the Thai coast used antibiotics in their farms. Of the seventy-six farmers interviewed, 74% used antibiotics in shrimp pond management, with at least thirteen different antibiotics being used. Many farmers were not well informed about efficient and safe application practices.

The overuse of antibiotics in shrimp farming can have significant implications for global health. It can exacerbate the rise of antimicrobial resistance, where drugs become ineffective against infection. A study in The Lancet medical journal found that more than 1.2 million people died from bacterial AMR globally in 2019.

To address the issue of antibiotic resistance, regulators have enacted legislation that adopts a zero-residue tolerance level. However, enforcing these laws is challenging, and it is unlikely that this will change in the near future. A balance must be found between realistic and ideal solutions. Ideally, antibiotics should only be used based on science-based determinations of the underlying cause of disease.

Chemical pollution

Shrimp farms have been associated with chemical pollution, which can have detrimental effects on the environment and nearby ecosystems. This is primarily due to the release of nutrient-rich waste and chemicals into surrounding waterways and the ocean.

In Vietnam, for example, intensive shrimp farming methods have led to organic pollution in nearby waterways. Farmers often discharge pond wastewater without treating it, leading to a rise in chemical use to rid the water of organic matter, further polluting the water and creating a cycle of contamination. The use of chemicals, medications, and supplements to maintain shrimp health contributes to this issue, as these substances are released into public waterways along with old pond water.

Additionally, shrimp farms contribute to groundwater pollution. Research has found that salt water from shrimp farms can seep into groundwater, affecting subsurface salinization, groundwater quality, and composition. The wider the farm, the longer it takes for the aquifer to regain its freshness during the non-shrimp-growing season. This salinization of groundwater can have lasting effects on the environment and local ecosystems.

The layout and design of shrimp farms also play a role in pollution levels. Studies have shown that the shape and size of shrimp ponds can impact groundwater pollution and coastal water quality. Optimizing farm layouts can help reduce the environmental impact and improve water quality.

Furthermore, shrimp farms are often built on the site of mangrove forests, which are cleared to make way for ponds. This causes significant carbon losses, with the carbon intensity of shrimp farming from deforested mangroves being up to ten times greater than that of beef grown in deforested rainforests. Mangrove forests are powerful climate tools, sequestering more carbon than terrestrial forests, and their destruction can have lasting consequences for the climate and local communities that rely on them for resources.

While some farmers are engaged in mangrove restoration work, the industry as a whole needs to take a more proactive role in recovering lost ecosystems and implementing sustainable practices. This includes reducing the use of chemicals and treating wastewater before releasing it back into public waterways. By addressing these issues, the shrimp farming industry can work towards minimizing its environmental footprint and the impact of chemical pollution on surrounding ecosystems.

Carbon emissions

Shrimp farms have been associated with high carbon emissions and significant environmental impacts. The production of shrimp contributes to greenhouse gas emissions (GHGs), including carbon dioxide (CO2), a major driver of global warming. At an average of 13 kg of CO2 equivalents per kilogram, shrimp production has a larger carbon footprint than most other seafood products, emitting about twice as much in greenhouse gases as salmon production.

The carbon footprint of shrimp farming can be divided into two main categories: feed production and energy use. Feed production accounts for about half of shrimp's carbon footprint. Shrimp diets are nearly 30% soy, and the expansion of soybean farms is a leading driver of land conversion and deforestation in South America. The other half of the carbon footprint comes from the energy used to mechanically pump and aerate water. The use of electricity for pumping and aeration accounts for a significant portion of emissions.

The geographical pattern of emissions closely mirrors production, with most emissions occurring in regions with the highest production, such as East Asia and South Asia. Shrimp farming in these regions contributes to a significant proportion of total aquaculture emissions. Additionally, the assumed lifetime of a shrimp pond is important, as emissions are annualized or amortized over this time period. The longer a pond can be used, the lower the overall carbon footprint of farmed shrimp.

To reduce carbon emissions, sustainable practices in shrimp farming are essential. This includes improving energy efficiency through the adoption of energy-saving technologies, such as solar-powered aeration systems, and transitioning to renewable energy sources. Lending programs that provide financial support to farmers can also help address environmental and financial challenges by promoting sustainable practices and reducing on-farm carbon emissions.

Furthermore, the degradation of coastal ecosystems, particularly mangroves, due to shrimp pond development, has led to a massive loss of soil carbon and carbon sequestration capabilities. Mangroves are ecologically rich ecosystems that serve as carbon sinks, storing large amounts of carbon. The conversion of mangroves into shrimp ponds has resulted in the loss of about 58% to 82% of the ecosystem carbon stocks, impacting the biodiversity and climate change mitigation capabilities of these ecosystems.

Wastewater management

One of the primary concerns regarding shrimp farm wastewater is the presence of antibiotics and other chemicals. The overuse of antibiotics in shrimp farming, particularly in low- and middle-income farms, contributes to the development of antimicrobial resistance (AMR). AMR occurs when disease-causing microorganisms become resistant to drugs specifically designed to combat them, posing a significant threat to the environment and potentially impacting human and animal health in the future. Additionally, chemicals such as salt, lime, potassium permanganate, malathion, formalin, and bleaching powder used in shrimp farming have been implicated in contributing to water pollution.

The organic load in shrimp farm wastewater is another critical factor in wastewater management. Organic matter, primarily from aquafeed, can lead to excessive nutrient levels in the water, including high levels of nitrogen and phosphorus from shrimp feces. This, in turn, can cause excessive algae growth and potentially lead to algae blooms in water bodies receiving effluents from shrimp farms. To mitigate this, farmers can optimise their feeding schedules and techniques, using high-quality feed and implementing appropriate feeding practices to reduce excessive nutrients. Regularly siphoning the organic load that settles as sludge on the pond bottom can also help decrease ammonia concentration and maintain good water quality.

Nutrient levels in shrimp aquaculture wastewater are also influenced by farm management practices. The use of machinery, such as generators, water pumps, and vehicles, can result in oil spillage and the discharge of fuels and lubricants into shrimp ponds, causing pollution. Implementing a closed system can help retain organic matter and nutrients before wastewater discharge, allowing mangroves to flourish and attenuate nutrient levels before they reach the coastal environment.

Additionally, shrimp farms can utilise seaweed and milkfish as biofilters in post-treatment ponds to absorb and feed on organic waste, respectively, reducing the organic load and making the discharge water less polluting.

Overall, effective wastewater management in shrimp farms requires a combination of improved feeding practices, optimised organic load management, and the utilisation of natural treatments like seaweed and milkfish. By addressing these issues, shrimp farms can reduce their environmental impact and contribute to more sustainable practices.

Frequently asked questions