Invertebrate Welfare — April 2021

420 billion to 1 trillion silkworms and pupae killed annually

• I published a new piece of research with Rethink Priorities examining potential animal welfare issues in the silk industry. I estimate the scale of silk farming, and summarize the areas that ought to be of greatest concern. Some major takeaways:

  • I estimate that between 420 billion and 1 trillion silkworms and pupae are killed annually to produce silk.

  • The scale of disease on silk farms is a lot higher than I would have guessed: over 10% of silkworms farmed die of disease prior to cocooning, and most of the diseases seem to take several days to kill.

  • Based on time spent in potentially negative circumstances, a limited metric that should be taken lightly, diseases and pests cause around 99% of known days of suffering on silk farms (compared to 1% caused by slaughter).

    • Notably, past discussion on silk in the animal advocacy community has focused on slaughter, and on the (questionable) sentience of pupating silkworms. If the simple metric I used to compare slaughter and disease holds up, we might reduce more suffering overall by focusing on silkworms themselves, rather than the pupae. 

    • Many of the diseases and issues that silkworms face on farms sound quite unpleasant, such as parasites living on their bodies or chronic wasting diseases. Reducing the suffering caused by these diseases might be a better discussion point for silk advocacy than cocoon boiling. 

Animal welfare issues for aquatic crustaceans

• A new study published in Animals looked at slaughter methods used on decapod crustaceans, and tried to assess their relative painfulness.

  • The authors found that lobsters and crabs showed the fewest signs of pain and distress from slaughter by electrical stunning, or by a properly trained slaughterer using the best methods (splitting the animal with a knife or piercing its ganglia with an awl). 

  • Notably, the authors did not recommend live-boiling of lobsters, a slaughter method used at times in restaurants and grocery stores that has been called out in the past by animal advocacy organizations.

  • Unfortunately, as the authors note, legislation protecting crustaceans during transport and slaughter is minimal, so without legislative changes or public advocacy it is unlikely these findings will be implemented in the industry. 

• Research published in Science Advances reviewed the animal welfare risks posed by  the potential expansion of global aquaculture.

  • Notably, the study found that there was no scientific literature addressing the welfare of the 105 to 136 billion invertebrates (such as squid, octopuses, bivalves, crabs, and lobsters) that were reported by the FAO as being raised for food via aquaculture in 2018.

• There is hope for future animal advocacy in this space. Crustacean Compassion, a UK organization that campaigns for the humane treatment of decapod crustaceans, just received a two year, $787,000 USD grant from Open Philanthropy, a major funder in the animal welfare space.

Food safety aspects of edible insects

• The FAO has released a new evaluation of edible insects from a human food safety perspective.

  • While the report identified several areas of concern where edible insects might introduce food safety risks (bacterial introductions and parasites for example), the authors did not perform a comprehensive risk assessment, so it’s hard to take away any concrete lessons from it. It is clear that there are at least some minor risks to human health, most of which can be addressed by appropriate post-slaughter processing.

  • The report pointed out that insect farming today is at a much smaller scale than it might be at some point in the near future, so new food safety concerns may arise as the industry scales up.

• Just in time for the FAO report, the journal Viruses announced that it is accepting submissions for a special issue on “Viruses in mass-researed invertebrates,” so some of these uncertainties may be clarified over the next few years.

Miscellaneous links

• My Octopus Teacher, a documentary about the relationship between a diver and an octopus, won the Academy Award for Best Documentary.

  • The documentary touches on octopus sentience occasionally, and seems like one of the highest profile pieces of media released relating to invertebrate sentience and welfare.

  • Relatedly, a new experiment published in iScience found that there is behavioral and physiological evidence for affective experience in octopuses.

  • Scientific American, which covered both events together, quotes an unrelated researcher as saying that the study, “shows beyond a doubt that [octopuses] are capable of experiencing pain,” so I guess that’s settled.

  • An unpublished estimate found that between 70,000,000 and 830,000,000 octopi are slaughtered directly for food.

• Mars (the food company) announced that it is launching a black soldier fly larvae-based pet food line in the UK.

• UK company Oxitec has secured biosafety approval in Brazil to test their genetically modified fall armyworms, a significant development in gene-based insect control approaches.

  • Relatedly, a study used new RNAi pesticides to target a single insect species, a major breakthrough in the insect control space.

  • I plan to do a deepdive on RNAi pesticides and gene-based insect control next month, so stay tuned for more on this topic.