The science behind us.
There’s a school of science stacking up about the sustainability of wild-caught fish.
The Seas Matter Sustainable Nutrition Score.
Ray Hilborn and the Sustainable Fisheries team at the University of Washington have calculated for us the nutritional value of eating fish, versus the amount of carbon emissions generated by harvesting them, and compared this score with other animal meat protein.
This ‘Sustainable Nutrition Score’ is a emissions-per-nutrient ratio calculated by dividing CO2 emissions per kg by the nutrients per kg.
There are more key nutrients in 100 grams of fish than in any meat protein. Seafood has one of the best combinations of proteins and nutrients, including n-3 fatty acids and micronutrients such as vitamin D, vitamin B12, iron, and zinc. See this research in Nature for more.
The resulting ratios are:
|
Product [1] |
Nutrient Score |
KG CO2 per nutrient score |
Relative impact |
|
Hoki |
0.56 |
4 |
1.0 |
|
Chicken |
0.24 |
30 |
7.6 |
|
Pork |
0.19 |
42 |
10.5 |
|
Beef |
0.55 |
89 |
22.2 |
|
Lamb |
0.45 |
104 |
26.0 |
To keep comparisons fair, Hilborn’s team calculated the nutrient to weight value of meat proteins across these important nutrients.
This means the results will not fully represent the differing nutritional benefits. The best choice of food can vary based on individual dietary needs.
Hilborn’s team divided the CO2 emissions by nutrient score derived from datasets used in a March 2023 study. New Zealand’s hoki fish species was used to represent wild-caught New Zealand fish.
That means wild caught hoki has many times more key nutrients per unit of CO2 emissions than most meats;
7 times more than chicken.
10 times more than pork.
20 times more than beef.
It is important to note that the Sustainable Nutrition Score will differ between fish species. Some aquatic species and production methods (like aquaculture) deliver nutrition to diets with environmental costs at least as high as land-based meat production.
______________________________________________________
[1] Livestock data are global averages. NZ lamb and beef are likely lower, but not available in our source data.
Recent science.
1. The role of seafood in sustainable diets. March 2023. https://iopscience.iop.org/article/10.1088/1748-9326/ac3954.
The above study found that the lowest GHG emissions to meet average nutrient requirement values were found in grains, tubers, roots, seeds, wild-caught small pelagic fish, farmed carp and bivalve shellfish.
The highest GHG emissions per nutrient supply are in beef, lamb, wild-caught prawns, farmed crustaceans, and pork.
The authors concluded that some “fish and shellfish have GHG emissions at least as low as plants and merit inclusion in food systems policymaking for their potential to support a healthy, sustainable diet”.
2. Assessing seafood nutritional diversity together with climate impacts informs more comprehensive dietary advice. September 2022. https://www.nature.com/articles/s43247-022-00516-4#Sec2
The authors concluded: The highest nutrient benefit at the lowest emissions is achieved by consuming wild-caught small pelagic and salmonid species, and farmed bivalves like mussels and oysters. Many but not all seafood species provide more nutrition at lower emissions than land animal proteins, especially red meat, but large differences exist, even within species groups and species, depending on production method.
Small fish and salmon have the highest value of 12 essential nutrients of all foods studied.
Small fish and tuna, and some shellfish have the lowest GHG footprint of any meat protein.
Full sustainability.
We have to eat something, and eating always has some impact on the environment.
In contrast with intensive farming of meats and crops, for example, wild-caught fish uses no pesticides, fertilizer or antibiotics and almost no freshwater.
Wild-caught NZ fish have a lower overall environmental impact (rated by life cycle assessments, measuring GHG emissions, energy use, and water and air pollutions) than any farmed meat, and the fifth lowest impact of ALL food groups (beaten only by rice, beans, corn and wheat).
You can find an explanation of the relatively low costs at https://sustainablefisheries-uw.org/seafood-101/cost-of-food/.
Sustainable species.
Wild-caught NZ fish comes from one of the world’s best-managed fisheries. Ray Hilborn says New Zealand’s commercial fishing is one of the five most sustainable fisheries in the world.
This is reflected in the nation’s high sustainability ranking by the international Marine Stewartship Council. Two thirds of the deepwater catch in New Zealand is certified as sustainable by the Council. The fisheries include hake, hoki, ling, orange roughy, southern blue whiting, albacore tuna, skipjack tuna, and Ross Sea toothfish. See https://deepwatergroup.org/certification/ for more.
An independent study has found that there’s more abundance in the populations of MSC certified fisheries than in non-certified fisheries. https://www.frontiersin.org/articles/10.3389/fmars.2022.818772/full
Emissions from all sources.
The World Resources Institute compared food groups for their emissions footprint created by production and land-use change. See full explanation here: https://www.wri.org/data/protein-scorecard