Climate Impact Justification

Details for additional info points 2 and 3 from the Problem Statement.

Point #2

Step 1: Total carbon emissions from fisheries and aquaculture

Carbon emissions will mainly come from two sources - fisheries/fishing and aquaculture. In 2011, fisheries consumed about 40 billion litres of fuel which is equivalent to 179 million tonnes of CO2-equivalent GHGs (MTCO2E). 

The estimate for total annual emissions from marine and freshwater aquaculture in 2008 is 385 MTCO2E. Therefore, an estimate for total annual emissions would be 179 + 385 = 564 MTCO2E. 

Step 2: Carbon emissions percentage reduction value of cultivated meat

Note: CO2E = carbon dioxide-equivalent GHGs

To estimate the carbon emissions of harvesting seafood using current practices, we averaged all the per-species median emissions in the “Greenhouse gas emissions per kilogram of seafood” chart (not including chicken). This averages out to 8.81 kg CO2E per kg of edible weight. While not a perfect estimate since it doesn’t adjust for harvest tonnage, cross-referencing it with another study that breaks down emission impacts for aquaculture, we see that our value is reasonable. Most finfish have emission impacts that lie in the range of 4-6 kg CO2E/kg edible weight. However this data is for aquacultured fish, and since wild-caught fish tend to have a higher median emission impact, this would raise the overall estimate. At the end of the day, there’s no concrete number that can be found in literature so assumptions will need to be made. Our guess is that we’re probably not too far off and the true value may range anywhere between 4 to 15 kg CO2E per kg of edible weight (we’re definitely NOT drastically off like by a magnitude). We will just go with 8.81 kg CO2E per kg of edible weight since it’s the value we can back up with some evidence and math. 

It is projected that by 2030, cultivated meat’s emissions impact will be 2.82 kg CO2E per kg of edible weight. The study looks at cultivated meat in the context of chicken, pork, and beef, however, we think this number is also a good estimate for cultivated seafood’s emission impact too. This is because there is less variation in the way cultivated meat is produced. Whereas farming cows may differ from farming fish, in a cultivated setting they share a lot of similar processes such as bioreactors, serums, and facilities since the core concept is growing large amounts of cells in bulk.

The decrease from 8.81 kg CO2E per kg to 2.82 kg CO2E per kg of edible weight represents a 68% reduction.

A 68% decrease in annual carbon emissions in global fisheries and aquaculture (564 MTCO2E) would mean a reduction of 383.52 MTCO2E. 

Sources:

1.  https://ourworldindata.org/fish-and-overfishing#environmental-footprint-of-fishing 

2. Ex-ante life cycle assessment of commercial-scale cultivated meat production in 2030: https://doi.org/10.1007/s11367-022-02128-8 

3. Quantifying greenhouse gas emissions from global aquaculture: https://doi.org/10.1038/s41598-020-68231-8 

Point #3

In the long term, we will target the cultivated meat production of three commercially valuable species: rainbow trout (Oncorhynchus mykiss), carp (Cyprinus carpio), and walleye (Sander vitreus). We will estimate the carbon footprint impact of transitioning to cultivated meat production for these three species.

Step 1: Greenhouse gas emissions per edible weight of seafood

Original values are reported in X kg of carbon dioxide-equivalents GHGs (CO2E) for edible kg of seafood.

Common carp (farmed): 6.95 kg of carbon dioxide-equivalents =>  6.950 tonnes CO2E / edible tonne

Rainbow trout (farmed): 5.41 kg of carbon dioxide-equivalents => 5.41 tonnes CO2E / edible tonne

Walleye (farmed, fished): 18.91 kg of carbon dioxide-equivalents => 18.91 tonnes CO2E / edible tonne

Note 1: We are lacking data on the tonnes of wild-caught trout and carp. This may be because the vast majority of trout are farmed and not fished. 

Note 2: For walleye, the emissions number is based on the carbon footprint of “Other freshwater fish (farmed)” value, since the publication does not record any specific values for walleye. Emission numbers for farmed vs fished in general are not too far apart with farmed emissions generally being lower. Therefore, since walleye is mostly fished and not farmed, the actual emissions numbers may be higher.

Sources

1.  https://ourworldindata.org/fish-and-overfishing#environmental-footprint-of-fishing 

Step 2: Calculate harvested species by edible weight (per year)

To calculate edible tonnes, we need to know the carcass yield (carcass weight / body weight) of each species since the carcass represents the edible part of a fish. The carcass yield is the % of the fish that is edible.

Carcass yield

• Common carp: 66.21% (source #4, table 1)

• Rainbow trout: 80.2% (source #5, table 2)

• Walleye: 48.7% (source #6, table 2, technically may be fillet yield since carcass yield isn’t reported but that’s okay since fillet yield refers to the proportion of the whole fish that can be processed into fillets - which is stricter than carcass yield)

Common carp (farmed): 3,791,913 tonnes => 2,510,625 edible tonnes 

Rainbow trout (farmed): 855,982 tonnes => 686,498 edible tonnes

Walleye (fished): 451,744 tonnes => 219,999 edible tonnes

• Canada (Recreational fishery): 20 million / year (section 4.1 in source #3) * 11kg (average weight) => 220,000,000 kg = 220,000 tonnes

• Canada (Commercial fishery): average of 5,872,093 kg / year (section 4.3 in source #3: A total of 264,244,193 kg of fish has been caught from 1955 to 1999) = 5872 tonnes

• US (Recreational fishery): Assume the same as Canada.

• US (Commercial fishery): Assume the same as Canada.

Note: We are unable to find data on walleye fishery in the US. We’ll make the assumption that the true values are similar to those of Canada’s. The majority of the walleye population is concentrated in the Great Lakes (Southern Canada / Northern US) which is shared by both countries. However, the walleye population spans the entire continental US and most of Canada’s freshwater bodies. The numbers assumed here may still be an underestimation and actual fishery weight may be higher.

Sources

1.  "Capture production by principal species in 2012" (PDF)

2.  "World aquaculture production of fish, crustaceans, molluscs, etc., by principal species in 2012" (PDF)

3. Canadian Manuscript Report of Fisheries and Aquatic Sciences 2888: https://waves-vagues.dfo-mpo.gc.ca/library-bibliotheque/337847.pdf 

4. Potential for Genetic Improvement of the Main Slaughter Yields in Common Carp With in vivo Morphological Predictors: https://ncbi.nlm.nih.gov/pmc/articles/PMC6078046/ 

5. Flesh quality in large rainbow trout with high or low fillet yield: https://archimer.ifremer.fr/doc/00014/12532/9532.pdf 

6. Potential for Genetic Improvement of the Main Slaughter Yields in Common Carp With in vivo Morphological Predictors: https://ncbi.nlm.nih.gov/pmc/articles/PMC6078046/ https://www.ncrac.org/files/inline-files/WFS116secure.pdf

Step 3: Total annual carbon emissions

Multiply emissions by weight. MTCO2E stands for million tonnes of CO2-equivalent GHGs.

Carp: 6.950 tonnes CO2E * 2,510,625 edible tonnes = 17,448,844 tonnes CO2E ~= 17.449 MTCO2E

Rainbow Trout: 5.41 tonnes CO2E *  686,498 edible tonnes = 3,713,954 tonnes CO2E ~= 3.714 MTCO2E

Walleye: 18.91 tonnes CO2E * 219,999 edible tonnes = 4,160,181 tonnes CO2E => 4.16 MTCO2E

Total carbon emissions: 17.449 + 3.714 + 4.16 = 25.323 MTCO2E

This number is probably on the lower end since we have not factored in wild-caught trout and carp numbers, as well as the possibility of an underestimation of walleye fishery numbers (due to lack of proper US records) and walleye emissions per kg. 

Apply 68% reduction: 17.22 MTCO2E

Total carbon emissions after reduction: 8.103 MTCO2E