How Pollution Impacts The Taste Of Seafood

Seafood is a popular food choice for many, but the impact of human activity on the oceans is affecting the taste of seafood. Climate change, ocean pollution, and overfishing are some of the key issues threatening the sustainability of seafood and altering its taste and texture. From acidifying waters impacting the taste of shrimp to the presence of microplastics and toxic chemicals in fish, the flavour and safety of seafood are at risk. With rising global temperatures and more frequent natural disasters, the planet is at a critical juncture, and the consumption choices of humans will play a crucial role in mitigating these issues.

Ocean acidification and its impact on shrimp

Shrimp is America's favorite seafood, and it is essential to study how ocean acidification affects them to ensure the continued availability of shrimp cocktail, tempura, or tacos. This is especially important given the commercial importance and significant role of shrimp in food chains. While shrimp are generally thought to be less vulnerable to changing ocean chemistry, recent studies have revealed unexpected results that warrant further investigation.

Impact on Exoskeleton

The exoskeleton of shrimp plays a crucial role in their survival, providing cover, support, and protection. It also contributes to their camouflage abilities, as some species, such as the red rock shrimp, rely on transparency to hide from predators. Ocean acidification, caused by the absorption of carbon dioxide from the atmosphere, can affect the structure and composition of shrimp exoskeletons.

Increased Calcium Content

Studies have shown that exposure to higher-than-normal acidic conditions leads to a significant increase in the relative amount of calcium in shrimp exoskeletons. This increase in calcium results in a heavier, less flexible, and more brittle exoskeleton, which can impact the shrimp's movement and ability to escape predators. The exoskeleton may be more prone to fracture during defensive or escape behaviors, such as tail flipping.

Decreased Transparency

In addition to the increase in calcium content, ocean acidification also leads to a decrease in the transparency of shrimp exoskeletons. This reduction in transparency can hinder the shrimp's ability to camouflage and avoid detection by predators. The decrease in transparency is significant, with shrimp exposed to higher acidic conditions being five to seven times less transparent than those in normal conditions.

The impact of ocean acidification on shrimp exoskeletons could have far-reaching consequences for their survival and ecological interactions. While the studies provide valuable insights, further long-term experiments are needed to fully understand the biological, physiological, mechanical, and ecological implications of ocean acidification on shrimp. Additionally, the impact of ocean acidification on the taste of shrimp requires further investigation, as it may influence consumer behavior and encourage conservation efforts.

Microplastics in seafood

Microplastics are a global issue. They are microscopic plastic particles, usually defined as any plastic particle that is less than 5mm in length. They are found in all areas of the marine environment, from the ocean surface to the seafloor.

Microplastics are ingested by a wide variety of marine organisms, from planktonic organisms and larvae to small and large invertebrates, and fish. They are often found concentrated in an organism's digestive tract, but can also be found in circulatory systems and surrounding tissue.

Sources of Microplastics

Microplastics are released all over the world. They are a result of the breakdown of larger plastic items, but can also be found in personal care products, industrial abrasives, and pre-production plastic pellets. They enter oceans from maritime operations, but it is suspected that 80% originate from land-based sources.

Seafood Most Likely to Contain Microplastics

Bivalves like oysters, and those with high concentrations of sediment, like sea cucumbers, are the seafood most likely to contain microplastics. Animals higher on the trophic pyramid, meaning those that are larger and carnivorous, are also at risk. A 2022 study found microplastics in four out of five commercial fish species from Australia and New Zealand.

Human Health Risks

The effects of microplastics on human health are poorly understood. Microplastics themselves may not frequently end up in fish meat, but there is evidence that the chemicals they carry, including toxic substances like flame retardants and polychlorinated biphenyls, do.

Health officials estimate that less than 0.3% of microplastics can cross from the human gut into the body's lymph and circulatory systems. The very smallest of these microplastics are then able to access our body's organs. Exposure to microplastics has been linked to oxidative stress, cytotoxicity, neurotoxicity, immune system disruption, and more.

Mercury contamination

Mercury is released into the air through industrial pollution, and it can travel long distances before settling into lakes, rivers, and oceans. It is then absorbed or ingested by small organisms and gradually moves up the food chain, with its concentration increasing at each step. As a result, large predatory fish, such as sharks and tuna, can have high levels of mercury in their bodies.

Mercury is a toxic metal that can cause serious health issues even in small amounts. It can interfere with brain development, making it especially dangerous for young children and women who are pregnant or planning to become pregnant. The U.S. Environmental Protection Agency (EPA) estimates that more than 75,000 babies are born each year with an increased risk of learning disabilities due to their mothers' mercury exposure.

While mercury contamination in fish cannot be seen, smelled, or tasted, and cooking does not affect it, it poses a significant health risk. The Food and Drug Administration (FDA) and the EPA recommend that young children and women who are pregnant, breastfeeding, or planning to become pregnant avoid certain types of fish with high mercury levels, such as shark, swordfish, king mackerel, and tilefish. These fish have been found to contain high levels of mercury that can harm an unborn baby or young child's developing nervous system.

For pregnant or breastfeeding women, the FDA and EPA advise consuming up to 12 ounces (approximately two meals) per week of fish and shellfish with lower mercury levels. Some examples of fish low in mercury include shrimp, canned light tuna, salmon, pollock, and catfish. It is important to note that even fish sticks and fast-food sandwiches are typically made from fish with low mercury levels.

To ensure the safety of locally caught fish, it is recommended to check local advisories or contact the local health department. Additionally, when in doubt, choosing smaller fish like anchovies, sardines, and scallops can help reduce mercury intake as they tend to have lower mercury levels.

Antibiotics and pesticides in farmed fish

Seafood is unique in that, aside from some farmed fish, most of the seafood we consume is still caught in the wild. This means that the seafood we eat is exposed to a contaminated sea, and a lot of that pollution may be making its way into our bodies.

Farmed fish are treated with antibiotics and pesticides to keep them alive and disease-free. In Canada, antibiotics can only be used when they are required to fight disease, never to stimulate growth. In the past, most bacterial pathogens affecting farmed fish were treated with antibiotics. However, the majority of bacterial diseases may now be prevented using vaccines. This change in practice has drastically reduced the quantities of antibiotics used, which also reduces the risk of bacteria in the wild from becoming antibiotic-resistant. Nevertheless, there are still some diseases where vaccine treatments are not available or successful, and farmers rely on antibiotics to treat infected animals.

Pests and infectious pathogens can occur in both wild and farmed fish, and can affect the health of aquatic ecosystems. The use of pesticides and drugs to treat fish infested with pests or pathogens is sometimes necessary for fish welfare, but it needs to be managed to minimize the risk of any potential environmental effects. In Canada, all pesticides and veterinary drugs require pre-market authorization by Health Canada, and pesticides are regulated under the Pest Control Products Act. Health Canada conducts rigorous, science-based, pre-market assessments to determine if the risks associated with the use of pesticides are acceptable, and includes environmental requirements, such as restrictions on use, to mitigate any environmental risks.

Despite these regulations, the use of pesticides and antibiotics in fish farming significantly contributes to marine pollution. A 2018 report to the Canadian Parliament concluded that little progress had been made in improving the situation. The report stated that "Fisheries and Oceans Canada had not made sufficient progress in completing risk assessments for key diseases, which were required to assess the effects of salmon farming on wild fish."

Climate change and seafood scarcity

Seafood is an important source of nutrients for humans, but climate change poses a significant threat to its availability and taste. According to research, over 90% of seafood production is vulnerable to climate change, with producers in the US and Asia facing the most significant risks.

Firstly, climate change will make seafood scarcer. Marine fisheries production peaked in the 1990s, and since then, the availability of nutrients such as protein, iron, calcium, and omega-3 from seafood has declined. Climate change will further reduce nutrient availability, especially in tropical low-income countries that heavily rely on seafood for their diet.

Secondly, climate change will also alter the taste of seafood. For example, acidifying waters will impact the taste and texture of shrimp. A study by Sam Dupont of the University of Gothenburg in Sweden found that shrimp exposed to higher carbon dioxide levels had a less flavorful taste.

In addition to scarcity and taste changes, climate change will also make seafood more dangerous to consume. Warmer waters will increase the prevalence of Vibrio pathogens and harmful algal blooms, posing health risks to humans.

The impact of climate change on seafood is a pressing issue that requires urgent attention to ensure food security and sustainability.

Frequently asked questions