Nutrients available in seafood could fall by 30 percent in low-income countries by the end of the century due to climate change, a new UBC study suggests.
This is in a scenario of high carbon emissions and low mitigation, according to the study published today in Climate change. This decline could be reduced to around 10% if the world manages to meet the Paris Agreement goals of limiting global warming to between 1.5 and 2 degrees Celsius – something recent reports have shown we are not on track to achieve.
“Low-income countries and the Global South, where seafood plays a central role in the diet and has the potential to help combat malnutrition, are hardest hit by the effects of climate change,” said first author Dr. William Cheung, professor and director of the study. UBC Institute of Oceans and Fisheries (IOF). “For many, seafood is an irreplaceable and affordable source of nutrients. »
Researchers examined historical databases of fishing and seafood farming, or mariculture, including data from UBC’s Sea Around Us to discover the amounts of key nutrients that were available in the past through fishing and seafood farming, and used predictive climate models to project them into the future. . They focused on four nutrients that are abundant in seafood and important to human health: calcium, iron, protein, and omega-3 fatty acids, the latter of which are not readily available in other food sources. .
They found that the availability of these nutrients peaked in the 1990s and stagnated until the 2010s, despite increases brought about by seafood farming and fishing for invertebrates such as shrimp and oysters.
Calcium sees the biggest decline
In the future, the availability of all four nutrients from catches is expected to decline, with calcium hardest hit, with a projected decline of around 15 to 40 percent by 2100 under an emissions scenario. low and high, respectively. Omega-3s would see a decrease of about five to 25 percent. These declines are largely due to decreasing quantities of pelagic fish available for capture.
« Small pelagic fish are very rich in calcium, so in areas of the world where people have milk intolerances or where other animal foods, like meat and dairy, are much more expensive, the fish is really essential to people’s diets,” the senior said. author Dr Christina Hicks, Professor at Lancaster University. “In many parts of the world, particularly in low-income tropical countries, fish provides nutrients that are lacking in human diets.”
Although seafood farming will provide more nutrients in the future compared to current levels, researchers predict that these increases will not be able to offset fishing-related losses. In a high emissions scenario, any gains in nutrient availability from seafood farming before 2050 would be lost by 2100.
“The main reason for this is climate change, which also poses a significant threat to seafood farming, leaving us with a growing nutritional deficit,” said co-author Dr Muhammed Oyinlola, a postdoctoral researcher at the department in zoology at UBC and at the Institute. national scientific research. “Seafood culture alone cannot provide a global solution to this complex problem. »
The availability of all four nutrients from tropical waters in generally low-income countries, such as Indonesia, the Solomon Islands and Sierra Leone, is expected to decline sharply by the end of the century under a high emissions scenario, compared to a minimal decline in higher-income countries. , non-tropical waters, such as those of Canada, the United States and the United Kingdom
Globally, researchers project that nutrient availability from seafood would decline by about four to seven percent per degree Celsius of warming. For low-income tropical countries, including Nigeria, Sierra Leone and the Solomon Islands, the projected decline would be two to three times the global average, or nearly 10 to 12 percent per unit of warming.
“This research highlights the impact of each degree of warming,” Dr Cheung said. “The more we can reduce warming, the less risk there is to marine and human life. »
Use a whole fish
Certain types of fish, like anchovies and herring, are packed with nutrients but are often used for fish meal and oil because these nutrients also promote fish growth. Likewise, many countries only keep certain parts of a fish for sale. The researchers highlighted potential adaptations to increase the availability of nutrients from seafood, conserving more of these nutritious fish for local human consumption, as well as reducing food waste in the production and consumption of seafood. fishing using all parts of a fish, including the head and fins.
“Future development of seafood supply must take into account the nutritional security of vulnerable groups, not just economic benefits,” said Dr Cheung. “But there is a limit to the effectiveness of these interventions, so it is important to limit global warming as much as possible.”
Language(s) of interview: English (Cheung, Hicks, Oyinlola), Cantonese (Cheung)
