Invertebrate Welfare — September 2020
At least 29 trillion to 57 trillion invertebrates impacted annually by humans
With Rethink Priorities, I recently evaluated the total number of invertebrates (not including nematodes), killed or used by humans in as many industries as I could find.
I considered animals who were killed or used directly or intentionally. For example, I included insects intentionally killed by pesticides, but not those killed by climate change, since the latter’s deaths might be considered indirect.
I did not look at very small industries, such as wasps killed during gall ink production, or industries that use animals that seem unlikely to have valenced experiences, such as sea sponge harvesting.
I also did not include nematodes, such as those used for biological control, due to difficulties estimating the scale of their use.
Finally, I did not include unintentional invertebrate deaths caused by humans, such as insects that are stepped on or hit by cars.
The breakdown of these numbers by animal and use is somewhat complicated by the fact that invertebrates are often grouped in taxonomically inconsistent ways (e.g. “shrimp farming” may involve a large number of different shrimp, while scientific research on flies is almost always Drosophila melanogaster). Overall, I considered around 100 different animal-use scenarios in 18 broader industries.
In total, rigorous estimates exist for only 16 of these animal-use types. The data for these animals suggest that at least 7.2 trillion to 26 trillion invertebrates are killed annually, and 18 trillion to 40 trillion are used non-lethally each year for various purposes.
For industries without solid data, I developed my own rough estimates. If correct, my calculations suggest that the vast number of invertebrates are killed in industries for which we have no good data, comprising between 100 trillion and 10 quadrillion invertebrates (not including nematodes).
My estimates suggest that agricultural pesticides are the single largest contributor to direct human impact on invertebrates by a significant margin. Other industries that I estimate affect >1 trillion individuals annually include: food/feed production, carmine dye production, shellac production, waste processing, non-agricultural pesticide applications, and pollination or conservation services.
While these topline numbers are extremely high, they don’t account for the quality of these animals’ lives — it could be the case, for example, that many bees kept for pollination services live net-positive lives.
My top takeaway from this project is the importance of finding humane insecticides (or possibly reducing insecticide use / advocating for insecticide alternatives). This is plausibly one of the best ways we could help invertebrates impacted directly by humans, though at present progress is stymied by a lack of information on insecticide painfulness.
Invertebrate welfare news
Jonathan Birth published “The search for invertebrate consciousness” in Noûs, one of the most influential philosophy journals in circulation.
The article discusses the nature of historic approaches to evaluating invertebrate consciousness, and recommends a specific approach moving forward: “What's needed? At this stage, not more theory, and not more undirected data gathering. What is needed is a systematic search for consciousness‐linked cognitive abilities, their relationships to each other, and their sensitivity to masking.”
Notably, much of Birch’s recommended approach is similar to that taken by Rethink Priorities in 2019. There are still significant gaps in available research for pursuing this approach, so a lot more data gathering is required.
Birch is sympathetic to protecting the wellbeing of invertebrates despite being unsure about their sentience.
The Irish Times profiled a snail farm in Ireland (a country not known for snail farming).
The Scottish government funded and published an extended study of the cost-effectiveness of different sea lice treatments, finding that treatment of fish with hydrogen peroxide is the cheapest way to reduce sea lice populations on farmed fish.
This research might be helpful for informing future strategies for reducing sea lice.
Unfortunately, killing sea lice with chemicals (especially hydrogen peroxide), remains the most cost-effective method.
Farmers have been phasing out the use of hydrogen peroxide due to concerns about it also hurting fish, and because the chemical is decreasing in efficacy as the crustaceans become more resilient to it.
See also my previous comments on sea lice.
A new article found that mite species are going extinct at extremely high rates.
The use of insects as animal feed is becoming a regular topic in animal agriculture industry journals.
The Tyee, a Canadian magazine focused on British Columbia, published a long-form piece on Enterra Feed, and using insects and other products as alternatives to fishmeal.
Enterra is working to develop a black soldier fly larvae based fishmeal alternative, fed on food waste.
Currently, waste-fed insect meal is not cost-competitive with fishmeal, or even soy or corn. However, it is one of the most promising ways to drive down the cost of raising insects.
The article alerted me to a $70,000 prize for developing alternatives to fishmeal for carnivorous fish.
One more charity working on invertebrate welfare
Last month when I outlined charities that work to reduce invertebrate suffering, I missed Beauty Without Cruelty, a charity in India that has investigated an Ahimsa silk (or peace silk) farm.
Ahimsa silk production involves breeding wild moths instead of domesticated ones. Producers claim that silk cocoons from these moths can be harvested after metamorphosis is complete, meaning no animals are killed or harmed.
The size of the “cruelty-free” silk industry may be quite small: One farmer owns a patent on the process (patent application number 217/MAS/2002), and runs the only “Ahimsa silk” farm, although several other farms also claim to make cruelty-free silk, presumably using similar processes.
Beauty Without Cruelty wrote an article on an investigation of the Ahimsa farm, and concluded that because the process involves puncturing cocoons during metamorphosis, moths rarely survive after hatching, or are killed by the farmers.
Both Beauty Without Cruelty and the Ahimsa farmer report that it takes 1500 moths to produce 100 grams of silk. This is significantly higher than what I found (132 to 220 cocoons per 100 grams silk) using statistics from the FAO Silk Reeling and Testing Manual. [February 2021 edit — I’ve revised my model to include new disease loss data, and my current estimate is 230 to 560 worms per 100 grams, which is higher than previously, but not as high as other estimates].
The FAO manual seems better cited than most articles on this topic, but the farmer may have better information as a silk producer.
One possibility is that because Ahimsa moths are wild, they are less productive than domestic silk moths, which have bred to increase silk yields.
If this explanation is accurate, it suggests that Ahimsa silk ironically causes more deaths than normal silk if more than 8% to 15% of Ahimsa moths die in production. [February 2021 edit — I think that these loss rates are actually lower than the industry average for conventional silk production now].