Welcome to The Nonlinear Library, where we use Text-to-Speech software to convert the best writing from the Rationalist and EA communities into audio. This is: Estimates of global captive vertebrate numbers, published by saulius on the Effective Altruism Forum. Write a Review In this article, I list all the estimates I could find for numbers of vertebrates that are farmed or kept in captivity for various purposes. I also describe some groups of captive vertebrates for which I found no estimates. For some bigger groups of animals that are less well-known amongst animal activists, I also describe trends and main welfare concerns. The purpose of the article is to make it easier to find and compare estimates. Hopefully, this can also help animal advocates decide which issues to focus on. Note that I chose to focus on captive vertebrates simply to limit the scope of the article. Summary tables Estimates are summarized in the tables below. Numbers can also be explored in this spreadsheet. The rest of the article provides sources and explanations for these numbers. All figures are for the whole world unless otherwise specified. For brevity, I use M for a million (10^6) and B for a billion (10^9). Reptiles and amphibians table Fish table Note that all the numbers above exclude shellfish. I’ve found no estimates for : fish used as live bait in commercial fishing, fish trapped in nets and traps, fish hooked on hooks in commercial and recreational fisheries, food fish transported alive, other species of wild-caught fish suffocating in the air after landing. Chickens table Most of the 68.8B slaughtered chickens were raised specifically for meat, but the figure seems to include at least some slaughtered chickens from the egg-laying industry (see the appendix in Šimčikas (2019a)). According to FAOSTAT, in total there were 23.7B chickens alive in 2018. Other birds table I haven’t found estimates for the number of: ducks and geese live-plucked for their feathers and down, swiftlets farmed for their nests, ostriches farmed for meat Mammals table I haven’t tried finding the number of: animals raised in other pet mills (kitten mills, rabbit mills, etc.), animals raised in more humane pet breeding facilities, household rodent pests caught in traps, civets used to make civet coffee, elk farmed for food. Mixed species table I haven’t estimated the number of animals who are: kept alive in food markets, captured or captive-bred to be released into the wild as a Buddhist ritual to earn good karma (fangsheng), raised to be hunted in countries other than the UK, used in circuses outside of Europe, used for racing, fighting, and other forms of entertainment, kept in wildlife rehabilitation clinics, land animals bred in captivity to be released into the wild for species reintroduction programs. various species of animals kept in wildlife farms (see Standaert (2020)) Pets The table below presents Euromonitor International data, which has estimates of the number of pets in 53 countries,[1] which account for about 70% of the world’s human population. table If estimates in tables above seem difficult to compare and comprehend, it may be useful to look at the appendix where I convert estimates into units of time. Estimates can also be explored in this spreadsheet. Explanation of uncertainty levels In the ‘Uncertainty’ columns in the tables above, I describe the uncertainty for each estimate as low, moderate, high, or very high. Here is roughly what I mean by these words: Low - the estimate comes from a trustworthy source that explains how it arrived at the estimate. I’d be surprised if the estimate was off by a factor of 1.5 or more. In cases I provide a point estimate (e.g., “1M”), this means that I’d be surprised if the actual number was more than 1.5 times smaller or larger than the estimate. In cases where I provide a range (e.g., “1M–2M”), this means that I’d be surprised if the real number was more than 1.5 times larger than the upper bound or more th...