The views expressed here are my own, not those of my employers.
Summary
- I Fermi estimate the past cost-effectiveness of Shrimp Welfare Project’s (SWP’s) Humane Slaughter Initiative (HSI) is 433 DALY/$, which is:
- 28.8 times my estimate for the (marginal) cost-effectiveness of corporate campaigns for chicken welfare, such as the one supported by The Humane League (THL).
- 43.5 k times my estimate for the cost-effectiveness of GiveWell’s top charities.
- I calculate helping shrimps slaughtered via air asphyxiation is 21.0 times as cost-effective as helping those slaughtered via ice slurry.
- Consequently, holding the number of shrimps helped per $ constant, it is much better to target producers slaughtering shrimps via air asphyxiation.
- I believe SWP’s work on removing sludge from shrimp ponds might be even more cost-effective than HSI, but it is not clear.
Cost-effectiveness of HSI
The calculations are in this Sheet.
I estimate the past cost-effectiveness of HSI is 433 DALY/$, multiplying:
- 15 k shrimps helped per $, which I got from the product between:
- 0.0288 DALYs averted per shrimp helped, which I determined from the product between:
- An equivalent additional time of fully healthy life per shrimp helped of 0.931 years, which I obtained assuming:
- All of the shrimps helped transition to electrical stunning, half from air asphyxiation 62.5 % (= 1 - 0.375), and 37.5 % from ice slurry (= 0.75*0.5). I got these fractions assuming 75 % of the targeted producers use some form of ice slurry, half of those implement it properly, and the other half improperly to the point of it being practically equivalent to air asphyxiation. I made these assumptions having in mind Aaron’s comment at the end of this section.
- For ice slurry, Rethink Priorities’ (RP’s) estimates for the time in the types of pain defined by the Welfare Footprint Project (WFP). 0 h in annoying pain, 3.02*10^-4 h in hurtful pain, 0.0239 h in disabling pain, and 0.00604 h in excruciating pain. Feel free to check RP’s related post.
- For air asphyxiation: time in disabling pain equal to the maximum time during which shrimp can remain alive of 30 min, although Aaron noted he and his colleagues have seen some alive for 6 h; time in excruciating pain as a fraction of that in disabling pain equal to that of ice slurry (0.126 h); time in hurtful pain as a fraction of that in disabling pain equal to that of ice slurry (0.00633 h); and time in annoying pain as a fraction of that in hurtful pain equal to that of ice slurry (0 h).
- For electrical stunning: time in disabling pain equal to 1.39*10^-4 h (= 0.5/60^2), as Aaron mentioned shrimps are electrically stunned within 1 s, which I interpreted as a uniform distribution ranging from 0 to 1 s, whose mean is 0.5 s (= (0 + 1)/2); time in excruciating pain as a fraction of that in disabling pain equal to that of ice slurry (3.51*10^-5 h); time in hurtful pain as a fraction of that in disabling pain equal to that of ice slurry (1.76*10^-6 h); and time in annoying pain as a fraction of that in hurtful pain equal to that of ice slurry (0 h).
- 1 h of fully healthy life neutralises 1 h of hurtful pain.
- Disabling pain is 100 times as bad as hurtful pain. This means 14.4 min (= 24*60/1/100) of disabling pain neutralise 1 day of fully healthy life.
- Excruciating pain is 1 k times as bad as disabling pain. This implies 0.864 s (= 14.4*60/10^3) of excruciating pain neutralise 1 day of fully healthy life.
- RP’s median welfare range of shrimps of 0.031.
- An equivalent additional time of fully healthy life per shrimp helped of 0.931 years, which I obtained assuming:
My estimate for the past cost-effectiveness of HSI is:
- 28.8 times my estimate for the cost-effectiveness of corporate campaigns for chicken welfare of 15.0 DALY/$.
- 43.5 k times my estimate for the cost-effectiveness of GiveWell’s top charities of 0.00994 DALY/$.
In addition, I estimate the past cost-effectiveness of HSI linked to helping shrimps slaughtered via:
- Ice slurry is 32.0 DALY/$, or:
- 2.13 times the cost-effectiveness of corporate campaigns for chicken welfare.
- 32.2 k times the cost-effectiveness of GiveWell’s top charities.
- Air asphyxiation is 673 DALY/$, or:
- 44.9 times the cost-effectiveness of corporate campaigns for chicken welfare.
- 67.7 k times the cost-effectiveness of GiveWell’s top charities.
- 21.0 times (= 673/32.0) that linked to helping shrimps slaughtered via ice slurry.
Consequently, holding the number of shrimps helped per $ constant, it is much better to target producers slaughtering shrimps via air asphyxiation. I assumed the same number of shrimps helped per $ for both methods, so the higher cost-effectiveness of helping shrimps slaughtered via air asphyxiation comes from the respective reduction in the disease burden per shrimp being 21.0 times as large. Given this large difference, I asked Aaron whether he had any estimates/guesses for the fraction of shrimps HSI helps which were being slaughtered via each of the 2 methods. Here is Aaron’s reply:
This is tricky because the answer is kind of both...
Most of the producers we work with are already implementing some kind of ice slurry, as they typically sell to the European market, and ice slurry improves the quality (for example sometimes sodium metabisulfite is added to the slurry mix, which prevents discolouration).
However, for ice slurry to function as a slaughter method, the shrimp has to be submerged for long enough (which we currently understand to be over 30 seconds), and typically instead the crates of shrimps are “dipped” into ice slurry for a few seconds, so in reality once removed they die of asphyxiation/crushing.
Though it’s important to note that practices can vary significantly by country and production systems (and producer).
I am currently planning to direct my next annual donations to SWP.
Cost-effectiveness of sludge removal
SWP also works on removing sludge from shrimp ponds, which:
- Improves water quality via reducing un-ionised ammonia and hydrogen sulphide.
- Reduces stocking densities via making the ponds deeper, and SWP asking farmers to commit to lower densities as a precondition for the sludge removal.
Aaron noted he thinks most of the benefits come from the 1st point:
I also want to add that although we do ask farmers to lower their densities - densities in India are already pretty low anyway (at least in the remote villages we’re working in), so I don’t think most of the benefits are realised here, I do think it’s mostly water quality improvements (and primarily hydrogen sulphide and un-ionised ammonia).
I believe SWP’s work on removing sludge from shrimp ponds might be even more cost-effective than HSI, but it is not clear. I calculate high stocking density and un-ionised ammonia account for 5.32 and 7.72 times as much suffering as ice slurry slaughter. Nonetheless, Aaron caveated that:
Our current shrimps helped / $ / year on this is ~500 [i.e. 1/3 (= 500/(1.5*10^3)) of HSI’s] (though the India team keeps on optimising the process and bringing costs down, so this number is improving month after month - I’m hopeful this will eventually equal HSI).
Also worth noting that the scale here is much lower than that of HSI, each pond we work with typically stocks ~100,000 shrimps, meaning we're impacting in the range of 10s of millions of shrimps each year. Whereas with HSI, each producer we work with commits to stunning a minimum of 100 million shrimps. So even if cost-effectiveness here exceeded that of HSI, the number of shrimps helped will almost certainly be much higher with HSI.
It’s also tough to know here how to convert from per $/year to just per $, as sludge slowly re-accumulates, so the impact year after year is reduced (and the program hasn't been running for long enough for us to assess if farmers continue to remove sludge after our initial intervention).
Acknowledgements
Thanks to Michael Johnston for nudging me to Fermi estimate the cost-effectiveness of shrimp welfare interventions. Thanks to Aaron Boddy for feedback on some of the inputs. Thanks to Aaron and Michael for feedback on the draft.