Seafood to lose nutritional value due to climate change: Study

The study projects that the greatest losses of nutrients from seafood lie in tropical and low-income countries where current and future nutritional needs are greatest

According to a new study, nutrient availability in seafood is projected to decline by approximately 30% by 2100 in low-income countries with 4°C of warming, and by approximately 10% with 1.5–2°C of warming.

Climate change can impact the presence and abundance of catch, which impacts the total edible biomass. Changes in the distribution of species alter the composition of the catch, which can potentially have an impact on the nutritional value that can be derived from it. Aquaculture can be affected by climate change as well, including impacts on the risks of diseases, frequency of harmful algal blooms and availability of feed supplies from wild fish stocks.

The study published in Nature climate change looked at four nutrients found in seafood, namely, calcium, iron, omega-3 fatty acids and protein. By 2050, fisheries production of all four nutrients is projected to decrease by 5-10%, relative to levels in 2000 under ‘strong mitigation’ low greenhouse gas emissions (Shared Socio-economic Pathway (SSP)1–2.6) and 8 to 15% under ‘no mitigation’ high emissions (SSP5–8.5) scenarios.

The researchers used climate models to input environmental parameters, such as sea-surface and sea-bottom temperature, salinity and oxygen, and a simulation model to estimate changes in distribution, abundance and catch of marine fish and shellfish, as well as changes in aquaculture production.

Greatest nutrient loss in tropical and low-income countries

According to the study, the greatest losses of nutrients from seafood lie in tropical and low-income countries where current and future nutritional needs are greatest, resulting in global disparities in nutrient availability under climate change.

About more than 3 billion people get at least 20% of their daily animal protein from fish, and in some countries such as Bangladesh, Cambodia, the Gambia, Ghana, Indonesia, Sierra Leone and Sri Lanka, fish consumption accounts for 50% or more.

In terms of regional food security, low-income nations—which frequently rely more heavily on fish as a vital supply of nutrients—will confront far greater obstacles if the global agreement to keep warming far below 2°C of pre-industrial levels is not met. 

For example, without effective policy to mitigate greenhouse gas emissions, global atmospheric warming is expected to reach a level beyond 4°C above pre-industrial levels by 2100. For lower-income countries, this level of climate change corresponds to a projected ~30% decline in calcium, iron, omega-3 and protein availability from fisheries and mariculture by 2100. Even if the climate is stabilised closer to the 1.5–2.0 °C global warming targets specified in the Paris Agreement, risks remain (~10% decrease in nutrient availability) for lower-income countries.

The report said that these countries would also need to adapt to the projected impacts from any transient ‘overshoot’ of warming before global climate mitigation targets can be met. 

The study found that countries with greater incomes that are expected to have challenges in their seafood production can adjust by importing seafood from other regions, which would increase the availability of nutrients. These trade imbalances might intensify global competition for a finite seafood resource, making it more difficult for lower-income nations to address the growing gaps in nutritional availability brought on by climate change.

Since many poor nations along the coast depend on the ocean to meet their sustainable development goals, the additional obstacles posed by climate change will make it more unlikely that these significant social objectives will be met. The majority of nations where there are anticipated reductions in the supply of nutrients are also seeing population growth, which may make the risks to human nutrition worse.

In particular, most countries are expected to experience a decline in nutritional availability per capita under the SSP5-8.5 scenario. There is a stark contrast between population growth and declining nutrient availability in places like Nigeria, Sierra Leone, and the Solomon Islands, where coastal populations are expected to rise by more than 50% by 2050 compared to 2010. On the other hand, it is anticipated that high latitude nations like Finland and Russia will see increases in nutrient availability from their fisheries and mariculture, even after accounting for population fluctuations. This highlights how crucial it is to coordinate efforts and assume global responsibility in order to mitigate climate change and ensure food security.

Other studies have also found a reduction in omega-3 availability from fisheries and aquaculture has been estimated as a result of warming waters due to climate change. This could reduce by up to 58% by 2100, and will be most affected in inland Africa. A separate study estimated that more than 10% of the world’s population is vulnerable to nutrient deficiencies, such as vitamin B12 and essential long-chain omega-3 fatty acids, due to declines in fish catch caused by overfishing and climate change.

Potential solutions

The study recommended that the projected disparities in nutrient availability could be reduced by developing nutrient-sensitive management approaches that account for climate-driven impacts to capture fisheries and mariculture. Marine fisheries and mariculture should include objectives and plans of action that can assist in bridging the growing gaps in nutrient output, especially for those nations where climate change is putting seafood nutrient availability at danger.

Implementing nutrient-based fisheries governance and management systems would limit forecasted impacts on nutrient availability, and it is anticipated that doing so would boost fishing yields and profitability by accounting for species range shifts and productivity.

The study went on to say that the management and advancement of nutrient-rich fisheries and aquaculture also serves as a foundation for incorporating nutrient data into ocean planning that is climate resilient. For example, creating fishing zones that sustain long-term nutrient yields in light of anticipated changes in species distributions. Furthermore, it may be possible to lessen the current worldwide gaps in nutrient availability by allowing nations with populations deficient in nutrients to give priority to sustainable fishing and aquaculture (including freshwater) of the healthiest and least sensitive to climate change.

The study emphasised that limiting warming to under 2°C is critically important to reduce nutrient losses from agriculture and seafood sectors, especially in tropical and low-income countries that are most likely to be severely impacted.

The study highlighted the need for nutrition-and climate-sensitive fisheries management, with food-based trade policies developed to prevent the changes we predict in nutrients from seafood translating to substantial malnutrition and declines in public health.

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