Estimates of global captive vertebrate numbers

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:

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 than 1.5 times smaller than the lower bound.

  • Moder­ate - I’d be sur­prised if the es­ti­mate was off by a fac­tor of 2 or more.

  • High—I’d be sur­prised if the es­ti­mate was off by a fac­tor of 3 or more

  • Very high—I’d be sur­prised if the es­ti­mate was off by a fac­tor of 5 or more

Note that these are my sub­jec­tive un­cer­tain­ties. In many cases, I haven’t spent much time think­ing about them, so they shouldn’t be taken too se­ri­ously.

The rest of this ar­ti­cle ex­plains the sources for all of the es­ti­mates in the ta­bles above.

Rep­tiles and amphibians

Frog farming

Frogs are farmed mostly for their legs that are used as a del­i­cacy food in many coun­tries around the world. Warfield (2018) de­scribes welfare prob­lems in frog farms. It claims that farmed frogs suffer from over­crowd­ing, lack of food, fight­ing with each other, can­ni­bal­ism, dis­eases, fluc­tu­at­ing tem­per­a­tures, poor wa­ter qual­ity, and san­i­ta­tion. Frog farm­ing also causes im­por­tant ecolog­i­cal prob­lems (see Altherr, Goyenechea and Schu­bert (2011) and Ribeiro et al. (2019)).

Ac­cord­ing to FAO’s FishS­tatJ data, the world’s farmed frog pro­duc­tion in 2017 was 100,379 tonnes in live weight, of which 91% was pro­duced in China, 4.2% in Viet­nam, and 1.6% in Taiwan. It seems[2] that most of these frogs are Amer­i­can bul­lfrogs, but it’s un­clear.

Mean slaugh­ter weight for Amer­i­can bul­lfrogs seems[3] to be some­where be­tween 175g and 300g (FAO, Ayres et al. (2015), Lutz and Avery (1999), Mor­eira, Hen­riques and Fer­reira (2013)). If we as­sume that the mean slaugh­ter weight for all frog species is be­tween 100g and 350g and trust FAO’s 100,379 tonnes figure, we can es­ti­mate[4] that 290M–1B frogs were slaugh­tered in 2017. In con­trast, Gratwicke et al. (2010) es­ti­mates that be­tween 0.8B–3.2B frogs are con­sumed by peo­ple each year. How­ever, I think that Gratwicke et al. (2010) es­ti­mate is in­ac­cu­rate due to a mis­take.[5]

Amer­i­can bul­lfrog slaugh­ter age seems to de­pend greatly on an in­di­vi­d­ual and species, but the mean seems to be some­where be­tween 4 months and 20 months.[6] Based on this, we can es­ti­mate[7] that 96.7M–1.67B frogs that will be slaugh­tered are al­ive in farms at any time (in­clud­ing tad­poles).

This es­ti­ma­tion ig­nores frogs that die be­fore the in­tended slaugh­ter age. FAO claims that farmed Amer­i­can bul­lfrog stocks “can achieve a sur­vivor­ship of more than 50 per­cent.” Fur­ther­more, it men­tions that tad­poles are rou­tinely cul­led to lower com­pe­ti­tion. Mor­eira, Hen­riques and Fer­reira (2013) ob­served a pond in Brazil and es­ti­mated that the mor­tal­ity was 10% dur­ing the tad­pole phase, 35% dur­ing meta­mor­pho­sis and pre-fat­ten­ing phases, and 10% dur­ing the fat­ten­ing phase (that is about 53% dur­ing the en­tire life). To ac­count for mor­tal­ity, I sub­jec­tively in­crease the num­ber of farmed frogs and frog tad­poles al­ive at any time from 96.7M–1.67B to 120M–2.5B.

See foot­notes in this sec­tion for more de­tails about the es­ti­mates. Note that these es­ti­mates are very rough, and I have very high un­cer­tainty about them, es­pe­cially the num­ber of farmed frogs al­ive at any time.

Also, note that 2018 Ten­cent ar­ti­cle pre­dicts that the de­mand for frogs will grow rapidly in the next 3 to 5 years. Hence, my es­ti­mate (which is based on 2017 FAO data) may already be out­dated. I’m also un­cer­tain if FAO statis­tics I’m de­pend­ing on are ac­cu­rate.

Fi­nally, note that the es­ti­mate is only for farmed frogs. Many frogs are wild-caught, and these frogs suffer dur­ing cap­ture and slaugh­ter. E.g., Altherr, Goyenechea and Schu­bert (2011) de­scribes a prac­tice of re­mov­ing legs from liv­ing frogs with knives, scis­sors, or hands. Kus­rini (2005) claims in 1999–2002, In­done­sia ex­ported 3.8 tonnes of frozen frog legs, which were har­vested from an es­ti­mated 28M–142M wild-caught frogs. The au­thor also claims that the num­ber of frogs con­sumed within In­done­sia could be seven times larger. In con­trast, ac­cord­ing to FAO’s FishS­tatJ data, In­done­sia cap­tured only 1.5 tonnes of frogs in live weight per year in 1999–2002. This sug­gests that ei­ther FAO or Kus­rini (2005) statis­tics on wild-caught frogs are in­ac­cu­rate.

Tur­tle farming

Tur­tles are farmed for food, as well as for medici­nal prod­ucts or to be kept as pets. (Gong et al. 2009)). They are mostly farmed in China. Var­i­ous es­ti­mates show that their num­bers may be sub­stan­tial:

  • Ac­cord­ing to the statis­tics in FAO’s FishS­tatJ, in 2017, there were 371,400 tonnes of tur­tles pro­duced, of which 322,102 tonnes (87%) were Chi­nese soft­shell tur­tles raised in China.[8] Ac­cord­ing to FAO, Chi­nese soft­shell tur­tles are har­vested at the weight of “1.0-1.5 kg or more” and it takes them 1–2 years to reach this weight. Us­ing this in­for­ma­tion, we can es­ti­mate that in 2017, there were roughly 180M–320M Chi­nese soft­shell tur­tles har­vested, and 250M–550M al­ive at any time, in China. Th­ese num­bers don’t ac­count for pre-slaugh­ter mor­tal­ity.

  • An al­ter­na­tive es­ti­ma­tion can be made us­ing the data in Haitao et al. (2008). The pa­per de­scribes a 2002 sur­vey which found that there were at least 309M tur­tles housed in 684 sur­veyed farms in China, of which 303M were Chi­nese soft­shell tur­tles. The sur­veyed farms sold about 125M Chi­nese soft­shell tur­tles with a com­bined weight of 91,382 t. Us­ing this in­for­ma­tion and the 322,102 t figure from FAO, we can ex­trap­o­late that in 2017 in China there were 440M Chi­nese soft­shell tur­tles har­vested, and 1.07B al­ive at any time.

  • Gong et al. (2018) cites “a brochure printed for the 8th World Congress of Her­petol­ogy in China” to claim that 900M Chi­nese soft­shell tur­tle hatch­lings are raised in Chi­nese tur­tle farms ev­ery year, more than dou­ble the tur­tles har­vested an­nu­ally in my ex­trap­o­la­tions above.

  • Cai et al. (2014) claim that in Guang­dong province, there are 3.1M adult tur­tles who pro­duce 52M baby tur­tles an­nu­ally.

Haitao et al. (2008) also claims that most Chi­nese tur­tle farms op­er­ate ille­gally and are there­fore not known by the gov­ern­ment. If the situ­a­tion hasn’t changed, FAO num­bers could be an un­der­es­ti­mate. This could help ex­plain the gap be­tween the 900M figure cited in Gong et al. (2018) and my ex­trap­o­la­tions.

If the num­ber of tur­tles har­vested is twice as big, then the num­ber of tur­tles al­ive may be twice as big as my es­ti­mates sug­gest as well. Hence, over­all I think there are 180M–900M farmed tur­tles har­vested ev­ery year, and 250M–2.14B al­ive at any time. Note that these num­bers don’t ac­count for pre-slaugh­ter mor­tal­ity.

One source that seems to con­tra­dict these num­bers is the ab­stract of Zhou and Huang (2007). It claims that in De­cem­ber 2006, the stock of tur­tles in cap­tivity in China was only 2M–4M and that 30M–40M hatch­lings were pro­duced (pre­sum­ably per year). How­ever, the ar­ti­cle is rel­a­tively old, and I’m not sure if it cov­ers all the tur­tles farmed for meat. The ar­ti­cle doesn’t seem to even men­tion Chi­nese soft­shell tur­tles. (I can’t read the ar­ti­cle in full be­cause it’s writ­ten in Chi­nese).

Also, note that my es­ti­mates are only for one species of tur­tles and only for China. Tur­tles are also farmed in other coun­tries. E.g., ac­cord­ing to table 8 in the 2018 U.S. Cen­sus of Agri­cul­ture, 1.6M farmed tur­tles were sold in the U.S.

This video shows con­di­tions in one tur­tle farm but I don’t know if it is rep­re­sen­ta­tive. The video also men­tions that tur­tles are fed meat, fish and small shrimps.

Snake farming

Aust et al. (2017) claim that:

China and Viet Nam are con­sid­ered to be the largest and most im­por­tant pro­duc­ers of, and mar­kets for, snake meat. Calcu­lat­ing the to­tal size of the in­dus­try is difficult, al­though a con­ser­va­tive es­ti­mate for China and Viet Nam sug­gests there are at least 4,000 closed-cy­cle farms pro­duc­ing sev­eral mil­lion snakes of at least 15 taxa (CITES Man­age­ment Author­ity, Viet Nam and Guangxi Forestry Ad­minis­tra­tion, un­publ. data).

Willett (2013) claims that one Chi­nese village breeds 3M snakes per year for food and venom (which is used for medici­nal pur­poses). Another ar­ti­cle about the same village claims that there are over 6M snakes in the village, of which 4M are in a sin­gle farm. The ar­ti­cle also men­tions that dead chicks and frogs are used for feed­ing the snakes. I haven’t found any other es­ti­mates of farmed snake num­bers. Note that snakes are also farmed for their skins.

Sala­man­der farming

Cun­ning­ham et al. (2015) de­scribes the Chi­nese gi­ant sala­man­der farm­ing in­dus­try in China. It claims that these an­i­mals are an ex­pen­sive del­i­cacy in China. Ac­cord­ing to a 2012 es­ti­mate it cites, 70% of farmed Chi­nese gi­ant sala­man­ders were grown in Qin­ling Moun­tain re­gion in Shaanxi Province. The ar­ti­cle also claims that a 2011 cen­sus es­ti­mated that li­censed farms in Shaanxi Province housed 2.6M sala­man­ders (in­clud­ing hatch­lings, ju­ve­niles and adults). It would fol­low that about 2.6M /​ 0.7 = 3.7M sala­man­ders are be­ing farmed in China at any time. How­ever, Cun­ning­ham et al. (2015) claim that most of the farms are un­li­censed. Hence the cen­sus of li­censed farms didn’t cap­ture the full scale of the in­dus­try. Fur­ther­more, Sal­is­bury (2015) claims that “the in­dus­try has ex­panded mas­sively” since the cen­sus. Cun­ning­ham et al. (2015) also men­tion that the in­dus­try is rapidly grow­ing. Con­se­quently, the cur­rent num­ber of farmed sala­man­ders could be much higher.

Cun­ning­ham et al. (2015) claim in most cases, sala­man­ders are fed farmed fish, but the use of farmed frogs was also re­ported. The pa­per also men­tions that sala­man­ders are of­ten force-fed to speed up their growth.

Crocodile and al­li­ga­tor farming

Crocodiles and al­li­ga­tors are farmed for meat, leather, and other pur­poses.

AgriFu­tures Aus­tralia claims that “an av­er­age of 1.33 mil­lion crocodili­ans were har­vested an­nu­ally wor­ld­wide for the three years to 2010.” How­ever, it doesn’t provide a source for the claim.

Per­a­wong­metha (2017) claims “some 1.2 mil­lion crocodiles are kept on more than 1,000 farms in Thailand, ac­cord­ing to figures from the Thai de­part­ment of fish­eries.” After a brief search, I couldn’t con­firm this statis­tic.

Ac­cord­ing to Table 8 in the 2018 U.S. aqua­cul­ture cen­sus, there were 73,000 al­li­ga­tors sold whole in the U.S., down from 314,000 in 2013. How­ever, the amount of al­li­ga­tor hides and meat pro­duced has in­creased in the same pe­riod. Louisi­ana Depart­ment of Wildlife and Fish­eries claims that Louisi­ana’s farm­ers har­vest more than 280,000 farm-raised al­li­ga­tors an­nu­ally. Ac­cord­ing to Shirley and Elsey (2015), in 2014, there were 37 pro­duc­tion fa­cil­ities in four states (Louisi­ana, Florida, Ge­or­gia, and Texas), and the to­tal an­nual pro­duc­tion was slightly more than 350,000 crocodiles.

While the num­bers of farmed crocodiles and al­li­ga­tors are not huge, it could be that many more an­i­mals are kil­led to feed them. Brooks (2010) es­ti­mates that in Cam­bo­dia there are 32,999 to 159,376 farmed crocodiles, and they con­sume 2.7M–12.2M snakes per year. “Njeru (2016) claims that in Kenya, crocodiles are fed fish, blood-soaked maize, and other meats. Shirley and Elsey (2015) claims that in the U.S., they are fed high-pro­tein float­ing pel­lets but doesn’t ex­plain what they are made of.

Fish

Fish farmed for food

Es­ti­mates of the num­ber of farmed food fish slaugh­tered an­nu­ally:

Es­ti­mates of farmed food fish al­ive at any time:[9]

Open Phil’s es­ti­mate of farmed fish al­ive at any time takes into ac­count fish who die be­fore the in­tended slaugh­ter age, while Fish­count’s es­ti­mate does not. If OpenPhil didn’t take pre-slaugh­ter mor­tal­ity into ac­count, their es­ti­mate of farmed fish al­ive at any time would be 72.5B, which is slightly lower than the lower bound of the Fish­count es­ti­mate. Rea­sons for the dis­agree­ment be­tween the two es­ti­mates can be seen in the ‘Com­par­i­son to Fish­count’ sheet in the Open Phil spread­sheet. I think that Open Phil es­ti­mates are likely to be more ac­cu­rate be­cause they are more de­tailed. E.g., Open Phil ac­counts for the fact that the same species of fish are farmed un­til they reach a differ­ent age and weight in differ­ent coun­tries. Fur­ther­more, Open Phil made their es­ti­mate af­ter con­sid­er­ing the ev­i­dence pre­sented by Fish­count and de­cid­ing that some as­pects of their es­ti­mate could be im­proved.

From figure 5 in FAO (2018a), we can see that fin­fish aqua­cul­ture pro­duc­tion in tonnes has been grow­ing at an an­nual rate of 5% be­tween 2012 and 2016. In the ap­pendix, Cai and Le­ung (2017) ex­trap­o­late this trend and as­sume that the an­nual growth of global fin­fish aqua­cul­ture be­tween the mid-2010s and early 2020s will be 4.81%. Hence, even though OpenPhil’s es­ti­mates are based on rel­a­tively re­cent data from 2016, we should ex­pect farmed fish num­bers to be even higher now. If we as­sume that farmed fish num­bers are also grow­ing also at 4.81% per year, we can ex­trap­o­late that in 2020 hu­mans will slaugh­ter 92.1B ✕ (1.0481)^4 = 111B farmed fish and that there are 85.2B ✕ (1.0481)^4 = 103B farmed fish al­ive at any time in 2020.

Ac­cord­ing to the Open Phil spread­sheet, China has about 52% of the world’s farmed fish al­ive at any time. It is fol­lowed by In­done­sia (~10%), In­dia (~10%), Bangladesh (~5%), Egypt (~3.4%), Viet­nam (~2.7%), and Myan­mar (~2.6%).

Note that there is a lot of un­cer­tainty about all these es­ti­mates. Also note that all these num­bers ex­clude shel­lfish. Fish­count es­ti­mates that in 2017 hu­mans kil­led 43B–75B farmed crayfish, crabs and lob­sters, and 210B–530B farmed shrimps and prawns.

Pre-slaugh­ter mortality

Based on OpenPhil’s spread­sheet, I es­ti­mate that roughly 19B farmed fish die be­fore the in­tended slaugh­ter age (but af­ter they are trans­ferred from hatcheries) wor­ld­wide. How­ever, there is some rea­son to sus­pect that this num­ber could be much higher. In the ap­pendix of Šimčikas (2019b), I pre­sent some sources that claim that 600B–700B of fish fry per year were pro­duced in China in the early 2000s. I’m un­sure whether to trust these sources be­cause the claims seem very sur­pris­ing, as num­bers are much big­ger than I’d ex­pect.[9] Also, these num­bers may be too out­dated to be rele­vant. Nev­er­the­less, they weakly sug­gest that ei­ther mor­tal­ity rates in fish farms are higher, or OpenPhil and Fish­count un­der­es­ti­mate the num­ber of slaugh­tered farmed fish. It’s also pos­si­ble that some of these fish fry are bred to be re­leased into the wild or for other rea­sons.

Note that the 19B figure and Open Phil es­ti­mates don’t ac­count for the mor­tal­ity of very young fish in hatcheries. Similarly, sources I cite in the ap­pendix of Šimčikas (2019b) seem to talk about how many fish fry are pro­duced by hatcheries. Since many fish die in hatcheries, the to­tal num­ber of hatched fish is even higher.

Fi­nally, note that mor­tal­ity rates seem to be higher in young fish and much lower as fish ap­proach slaugh­ter. Hence, the im­pact that the pre-slaugh­ter mor­tal­ity has on the num­ber of farmed fish al­ive at any time is smaller than it would ap­pear at first glance.

Fish bred for stocking

In Šimčikas (2019b), I es­ti­mated that 35B–150B fish are raised in cap­tivity to be re­leased into the wild ev­ery year, mostly to in­crease the catch in com­mer­cial and recre­ational fish­eries. I am very un­cer­tain about the mean age at the time of the re­lease of these an­i­mals, but it seems to be some­where be­tween 8 days and 3 months. It fol­lows[10] that there should be 0.8B–50B fish be­ing raised in cap­tivity for the pur­pose of stock­ing at any time. This ex­cludes fish who die in hatcheries be­fore the re­lease. Since many of these fish are re­leased when they are ju­ve­niles and mor­tal­ity dur­ing the early stages is high, this could sig­nifi­cantly in­crease the num­ber of fish be­ing raised in cap­tivity at any time. Con­se­quently, I sub­jec­tively in­crease the es­ti­mate from 0.8B–50B to 0.8B–65B. As I ex­plain in Šimčikas (2019b), I think that the num­ber of fish stocked wor­ld­wide is more likely to be in­creas­ing than de­creas­ing, but I am un­cer­tain. Note that these es­ti­mates ex­clude shel­lfish who are also stocked in billions.

Fish bred for stock­ing may suffer in farms, dur­ing trans­porta­tion and re­lease. They also of­ten strug­gle and starve af­ter the re­lease due to a lack of sur­vival skills.

For a more in-depth overview of this prac­tice, see Šimčikas (2019b).

Fish farmed to be used as bait by recre­ational fish­ers (bait­fish)

In this con­text, bait­fish are small fish who are farmed and then sold to recre­ational fish­ers, who im­pale them on a hook and use them as live bait to catch big­ger fish. Farmed bait­fish suffer not only dur­ing farm­ing and when used as bait, but also when trans­ported and kept by whole­salers, re­tailers, and fish­ers.

I cov­ered the topic of bait­fish in more depth in Šimčikas (2018a). Since I wrote the ar­ti­cle, a 2018 U.S. aqua­cul­ture cen­sus was re­leased. Ac­cord­ing to the table 4 of the cen­sus, 1.2B bait­fish were sold in the U.S. in 2018. Similarly, ac­cord­ing to the the U.S. 2013 aqua­cul­ture cen­sus, 1.17B farmed bait­fish were sold in the U.S. in 2013 which sug­gests that the in­dus­try is cur­rently nei­ther grow­ing nor shrink­ing (con­trary to my claims in Šimčikas (2018a)).

Some sources sug­gest that the num­ber of bait­fish pro­duced in the U.S. is much big­ger than 1.2B. For ex­am­ple:

  • In this 2014 video by Arkansas Farm Bureau, a vice-pres­i­dent of the largest bait­fish hatch­ery claims that ev­ery year they pro­duce 1.3B golden shin­ers alone and that this num­ber doesn’t in­clude gold­fish and fat­head min­nows. Ac­cord­ing to the cen­suses men­tioned above, there are around 0.5B golden shin­ers sold an­nu­ally in the whole coun­try.

  • Stone et al. (1997) claim that in 1995 Arkansas pro­duced 6B bait­fish, uti­liz­ing 12,000 hectares of pro­duc­tion ponds. The ar­ti­cle claims that these figures were “[c]om­piled by in­di­vi­d­u­als from Arkansas aqua­cul­ture in­dus­try and gov­ern­ment aqua­cul­ture spe­cial­ists.” Ac­cord­ing to table 16 in the 2018 U.S. aqua­cul­ture cen­sus, there were nearly 10,000 hectares used to pro­duce bait­fish in the U.S. in 2018. Based on this, it could be ex­trap­o­lated that 10,000 ✕ 6B /​ 12,000 = 5B bait­fish were pro­duced in the U.S. in 2018. While I’m un­sure if this ex­trap­o­la­tion is ap­pro­pri­ate, I think it does sug­gest that the num­ber of bait­fish pro­duced could be sig­nifi­cantly higher than 1.2B.

I think the most likely ex­pla­na­tion of the dis­crep­ancy is that the two sources above write about how many bait­fish are pro­duced while the cen­suses re­port how many bait­fish are sold. Stone (2003) claims that “in most years many more pounds of [bait]fish are raised than can be sold.”

In Šimčikas (2018a), I wrote that “most farmed bait­fish are sold when they are about 1 year old”. This sug­gests that the num­ber of farmed bait­fish al­ive at any time is similar to the num­ber of bait­fish slaugh­tered an­nu­ally, which seems to be some­where be­tween 1B and 7B.

Note that all of these num­bers are for the U.S. only. Within the U.S., most of the bait­fish seem to be pro­duced in Arkansas (see table 16 in the 2018 U.S. aqua­cul­ture cen­sus). It seems that bait­fish are not farmed at a large scale in most other coun­tries. Ven­tura et al. (2017) show that bait­fish are also farmed for recre­ational fish­ing in Brazil, but I haven’t found what is the scale of this pro­duc­tion. In Canada, Aus­tralia, and prob­a­bly some other coun­tries, some fish are sold to be used as bait (see Kerr (2012), PIRSA (2018)). How­ever, I haven’t seen ev­i­dence of bait­fish be­ing farmed in these coun­tries, and it seems that in Canada they are wild-caught.

Wild-caught fish

Ac­cord­ing to Fish­count es­ti­mates, the av­er­age num­ber of wild-caught fish each year for 2007–2016 is 790B–2,300B. This es­ti­mate is based on FAO data. Page 93 in FAO’s SOFIA 2018 re­port claims that “it is rec­og­nized that the FAO cap­ture database does not in­clude all fish caught in the wild, as it omits the por­tion of the catch that is dis­carded at sea and catches from ille­gal, un­re­ported or un­reg­u­lated (IUU) fish­eries.” Pauly and Zel­ler (2016) es­ti­mate that be­cause of this is­sue, global catches be­tween 1950 and 2010 were roughly 50% higher than data re­ported to FAO sug­gest.

While wild-fish spend most of their life in the wild, there is a pe­riod be­tween be­ing caught and dy­ing that they spend in hu­man cap­tivity. There are many welfare is­sues dur­ing this pe­riod and they are sum­ma­rized in Mood (2010). It can be use­ful to es­ti­mate how many fish are suffer­ing from the is­sues de­scribed in Mood (2010) at any time and com­pare it with other an­i­mal prob­lems. In sub­sec­tions be­low, I at­tempt to make some such crude es­ti­mates.

An­chovies caught by purse sein­ers suffer­ing due to overcrowding

Ac­cord­ing to Fish­count es­ti­mates, the species that are caught in the high­est num­bers are an­chovies: 295B–908B per year (17%–65% of all wild-caught fish). Based on FAO de­scrip­tions, I es­ti­mated that 174B–880B of them are caught by purse sein­ers. To ac­count for ille­gal, un­re­ported or un­reg­u­lated fish­eries, I in­crease the up­per bound by 50% to 1,312B. Mood (2010) claims that the du­ra­tion of the most stress­ful pe­riod of purse sein­ing is when nets are tight­ened and fish can not school. Dur­ing this time, they ex­pe­rience stress due to over­crowd­ing, in­jury due to col­li­sions with the net and other fish. Mood (2010) cites Marçalo et al. (2006) to claim that this pe­riod lasts about an hour. If we as­sume that it’s 0.75–1.25 hours on av­er­age, we can es­ti­mate that 15M–187M an­chovies are in tight­ened purse seine nets at any point in time on av­er­age. Note that this es­ti­mate is only for an­chovies. Other fish species that are caught with purse sein­ers in­clude sar­dines, mack­erel, her­ring, and tuna. The es­ti­mate also ex­cludes fish caught by other fish­ing meth­ods and pos­si­ble suffer­ing of an­chovies dur­ing other parts of purse sein­ing.

purseSeiner

Chilean jack mack­erel caught by a purse seiner (source)

Fish suffo­cat­ing af­ter land­ing at any time

Mood (2010) claims that:

Most com­mer­cially-caught wild fish that are al­ive when landed are not slaugh­tered but die ei­ther from be­ing left to suffo­cate in air or by a com­bi­na­tion of suffo­ca­tion and live gut­ting. Some­times fish are put onto ice as they suffo­cate, or into iced wa­ter, which may both in­crease and pro­long their suffer­ing.

Ac­cord­ing to a Dutch study, dur­ing ob­ser­va­tion of fish­eries at sea, the ma­jor­ity of most fish species caught were still al­ive and con­scious when landed. The time taken to lose con­scious­ness was mea­sured for sev­eral species of fish (her­ring, cod, whit­ing, sole, dab, and plaice). Those left to as­phyx­i­ate took 55–250 min­utes to be­come in­sen­si­ble. Those who were gut­ted first re­mained sen­si­ble for 25–65 min­utes.

Fish suffer­ing dur­ing suffo­ca­tion seems to be in­tense. In most cases, vi­o­lent at­tempts to es­cape are made and a max­i­mal stress re­sponse is ini­ti­ated (Robb and Kesti (2002)).

The cited dutch study is Van de Vis and Kestin (1996), but I couldn’t ac­cess it. Ac­cord­ing to Fish­count, there are 30B–68B her­ring, cod, whit­ing, sole, dab, and plaice caught an­nu­ally.[11] To ac­count for ille­gal, un­re­ported or un­reg­u­lated fish­eries, I in­crease the up­per bound by 50% to 102B. If we as­sume that all of these species suffer from as­phyx­i­a­tion for 25–250 min­utes when they are out of the wa­ter and 50%–100% of these fish suffer from as­phyx­i­a­tion be­fore death, we get that on av­er­age 0.7M–49M her­ring, cod, whit­ing, sole, dab, and plaice are suffo­cat­ing in air af­ter be­ing landed at any time.[12] I am very un­sure about this es­ti­mate be­cause I have a very limited un­der­stand­ing of fish biol­ogy and com­mer­cial fish­ing. The es­ti­mate is based only on my in­ter­pre­ta­tion of the cited sources.

The com­bined num­ber of all wild-caught fish suffo­cat­ing in the air at any time could be much higher. Time taken to suffo­cate for fish species can be very differ­ent:

  • This video claims that “an­chovies die im­me­di­ately when they are out of wa­ter.” How­ever, the video is not about fish welfare and may ig­nore the fact that it takes some num­ber of min­utes for them to suffo­cate if it’s not eco­nom­i­cally im­por­tant.

  • Ac­cord­ing to Table 12-3 in EFSA (2004), time to loss of brain func­tion due to as­phyx­i­a­tion in the air is about 5.5 min­utes for Gilt­head sea bream and 2–3 min­utes for rain­bow trout. Note that these times are for spe­cific tem­per­a­tures. If rain­bow trout are iced, then they lose brain func­tion in about 10 min­utes (Table 12-4).

  • Fish­count claims that “there is anec­do­tal ev­i­dence of flat­fish landed by a trawl sur­viv­ing ten hours out of wa­ter.”

I’m un­sure if any of the cited sources as­sume that fish are al­ive just be­cause they con­tinue to move. This could be a mis­take be­cause fish can move af­ter their death. EFSA (2004) claims that “be­cause car­cass move­ment ceases af­ter con­scious­ness is lost, this crite­rion can­not be used as an in­di­ca­tor of death.”

Other

I made the es­ti­mates above only be­cause I was able to find some rele­vant num­bers, not be­cause I be­lieve these to be the most im­por­tant groups of an­i­mals suffer­ing in cap­tivity due to fish­ing. Other groups of wild-caught fish in cap­tivity in­clude:

  • Fish trapped in nets. Mood (2010) de­scribes how fish get trapped in nets, are in­jured in the pro­cess and then may strug­gle in nets for many hours or even days un­til the net is re­trieved.

  • Longline fish­ing is a com­mer­cial fish­ing method that uses hun­dreds or even thou­sands of baited hooks hang­ing from a sin­gle line, which may be 50–100 km long. Fish caught on long lines may stay hooked for hours or days un­til the gear is hauled up. Dur­ing this time, they may be at­tacked by preda­tors and par­a­sites (Mood (2010)).

  • Bait­fish used in com­mer­cial fish­eries. Mood (2010) claims that fish are some­times used as live bait in var­i­ous com­mer­cial fish­ing meth­ods. It seems that all (or al­most all) of these fish are wild-caught. Ac­cord­ing to Mood (2010), “these bait fish will have suffered fear and dis­tress caused by cap­ture and con­fine­ment, pos­si­bly for days or weeks, be­fore they are im­paled on hooks or scat­tered live amongst shoals of tuna.” I haven’t found any es­ti­mate of how many bait­fish are used by com­mer­cial fish­ers. How­ever, the num­bers could be very sig­nifi­cant. The last para­graph of Mood and Brooke (2019) very roughly es­ti­mates that 134B–324B fish are used for non-food pur­poses (other than fish­meal and fish oil) ev­ery year. Ac­cord­ing to FAO (2018b), this in­cludes us­ing fish “for feed and bait, for or­na­men­tal pur­poses, with­drawals from mar­kets and any other non-food use of fish pro­duc­tion (e.g. fer­til­iz­ers, med­i­cal uses).” How­ever, I don’t know what pro­por­tion of the es­ti­mated 134B–324B fish are used as live bait or feed in com­mer­cial fish­ing. Note that these fish are not in­cluded in my es­ti­mate of the num­ber of bait­fish farmed for recre­ational fish­ers.

Farmed feeder fish

Feeder fish are fish that are sold in or­der to be eaten (some­times al­ive) by other cap­tive an­i­mals, like rep­tiles, big­ger fish, and sharks. Woemp­ner (2012) de­scribes cruel con­di­tions in which feeder fish are kept in some U.S. pet stores.

Arkansas Farm Bureau (2019) con­tains a video about a U.S. farm which re­port­edly raises around 175M gold­fish each year. In the video, it is claimed that the ma­jor­ity of these fish are fed to aquar­ium fish. This sug­gests that feeder fish num­bers can be sig­nifi­cant.

I’m un­sure how preva­lent is the prac­tice of us­ing feeder fish to feed aquar­ium fish around the world. Clarke (2006) claims that the use of feeder fish is rel­a­tively com­mon in the U.S., but vir­tu­ally un­heard of in the UK.

Note that in this sec­tion I ex­clude wild-caught fish used to feed other an­i­mals, which are much more nu­mer­ous. Mood and Brooke (2019) es­ti­mate that 460B–1,100B fish are re­duced to fish­meal and fish oil ev­ery year (the es­ti­mate is based on 2007-2016 FAO data). Most of this fish­meal and fish oil is then fed to farmed an­i­mals, mostly farmed fish and crus­taceans. Fur­ther­more, some wild-caught fish are used as feed with­out be­ing re­duced to fish­meal and fish oil.

Cleaner fish

Cleaner fish is a term used to re­fer to species that are de­ployed in farmed salmon cages to pick off and eat the sea lice from pass­ing fish. The pre­dom­i­nant species used are Bal­lan wrasse and lumpfish (Marine Con­ser­va­tion So­ciety (2018)). Ac­cord­ing to Pow­ell et. al. (2017), there were well over 30M lumpfish ju­ve­niles de­ployed in 2016. It also claims that to meet global in­dus­try needs, lumpfish pro­duc­tion needs to in­crease to reach 50M fish an­nu­ally by 2020, 10M of which re­quired in the UK. Ac­cord­ing to Nor­we­gian Direc­torate of Fish­eries (2018), in 2018 in Nor­way there were 2M farmed wrasse and 29M farmed lumpfish sold as cleaner fish. This ex­cludes wild cleaner fish. In to­tal, 49M cleaner fish were used in Nor­way in 2018. Ac­cord­ing to Fish­count statis­tics, about half of the farmed salmon is pro­duced in Nor­way. Based on that and other sources, my im­pres­sion is that Nor­way ac­counts for the ma­jor­ity of used cleaner fish and that the num­ber of cleaner fish de­ployed around the world does not ex­ceed 90M. Cleaner fish welfare prob­lems are de­scribed in OneKind (2018).

Vaughan, Grut­ter and Hut­son (2018) claim that cleaner shrimps could be used in fish farm­ing of var­i­ous species in the fu­ture. This could sig­nifi­cantly in­crease the num­ber of an­i­mals in­volved in fish farm­ing.

Eel trafficking

There is a high de­mand for eels as food in Ja­pan and China. This de­mand can no longer be met by wild-caught eel due to de­creas­ing catches. It is also not known how to grow eel through their en­tire life­cy­cle in cap­tivity (The Economist (2019)). In­stead, mil­lions of baby eels are caught from the wild, ille­gally traf­ficked from Europe to Asia where they are grown in farms and slaugh­tered. Ac­cord­ing to Galey and Billing (2018), eels are smug­gled in vans and lor­ries, put into suit­cases, and then flown by com­mer­cial air­lin­ers. In ad­di­tion to an­i­mal suffer­ing that this may in­volve, the pro­cess is also con­tribut­ing to the de­cline of eel num­bers in the wild.

Ac­cord­ing to Europool (2018), “it is be­lieved that, for the cur­rent sea­son, 100 tonnes of eels have been smug­gled from EU to China”. Ac­cord­ing to The Economist (2019) and Galey and Billing (2018), 100 tonnes is about 300M–350M eels. How­ever, Sus­tain­able Eel Group (2018) claims that the quan­tity of eels smug­gled an­nu­ally is some­where in the mid­dle of the range of 8 tonnes (about 28M eels) and 100 tonnes. They also claim that this quan­tity “varies enor­mously from year to year.” Note that none of these eels seem to be ac­counted for in the FAO statis­tics that farmed fish es­ti­mates in this ar­ti­cle are based on.

In ad­di­tion to eels traf­ficked from Europe, Tjan­dran­ingsih (2013) claims that eels are also traf­ficked from In­done­sia. I’m un­sure if there are other an­i­mal species that are traf­ficked in such huge num­bers. Galey and Billing (2018) and The Economist (2019) claim that eel is the most traf­ficked an­i­mal in the world.

Stur­geons farmed for caviar

Caviar is made from fish eggs, mainly stur­geon eggs. EUMOFA (2018) claims that “from a global point of view, pro­duc­tion of stur­geon, and es­pe­cially caviar, is very small.” Ac­cord­ing to Bronzi et al. (2019), the global farmed caviar pro­duc­tion has pro­gres­sively in­creased over the last 15 years, with pro­duc­tion in 2017 amount­ing to ap­prox­i­mately 364 tonnes. Romeo (2019) claims that one Ital­ian caviar farm houses 300,000 stur­geons. The ar­ti­cle claims that this and an­other Ital­ian caviar farm to­gether pro­duce 25 tonnes of caviar. From these and other figures, I ex­trap­o­late[13] that there are around 10.75M stur­geons farmed for caviar in the world at any time. Ehret (2019) claims that one Chi­nese farm keeps 200,000 stur­geons and pro­duced 86 tonnes of caviar last year. From this we can ex­trap­o­late that 200,000 ✕ 364 tonnes /​ 86 tonnes = 846,511 stur­geons are used for caviar pro­duc­tion globally. Based on these ex­trap­o­la­tions, I think it’s that the num­ber of stur­geons farmed for caviar in the world at any time is most likely to be some­where be­tween 1M and 15M. My im­pres­sion is that the num­ber of all other species of fish farmed for their eggs is sig­nifi­cantly lower.

FAOSTAT land an­i­mal numbers

The most widely used statis­tics about farmed land an­i­mals come from the Food and Agri­cul­ture Or­ga­ni­za­tion of the United Na­tions web­site FAOSTAT. It con­tains es­ti­mates of the num­ber of an­i­mals slaugh­tered and al­ive at any time in each coun­try and for each year. Th­ese statis­tics are col­lected by coun­tries and ag­gre­gate offi­cial, semi-offi­cial, and es­ti­mated data. To my knowl­edge, these are also the best available statis­tics on the topic. How­ever, there are some in­con­sis­ten­cies in them that sug­gest ac­cu­racy is­sues (see Šimčikas (2019a)).

In the table be­low, I com­bined FAOSTAT live an­i­mals and live­stock pri­mary num­bers for 2018 for all coun­tries. “Main uses” column is filled by me based on brief web searches.

table

The num­bers in the table may not add up due to round­ing. For more pre­cise num­bers, see this spread­sheet or the FAOSTAT web­site.

Th­ese an­i­mals are used for var­i­ous pur­poses. FAO claims that “the data on live­stock num­bers are in­tended to cover all do­mes­tic an­i­mals ir­re­spec­tive of their age and the place or pur­pose of their breed­ing.” How­ever, these stats seem to ex­clude quail, an­i­mals used for re­search, minks farmed for fur, ro­dents farmed for pet snake food, etc. I’m also un­sure if the FAOSTAT num­bers in­clude all the an­i­mals kept by sub­sis­tence and small-scale farm­ers (e.g., chick­ens kept in back­yards).

It is difficult to de­ter­mine how many an­i­mals are used for what pur­pose. This task is com­pli­cated by the fact that the same an­i­mal is of­ten used for mul­ti­ple pur­poses. E.g., the same cow may be used for milk, work­ing, meat, and leather. Similarly, the same sheep may be used for wool, meat, and milk, al­though most sheep breeds are spe­cial­ized for one or two of these pur­poses.

Live an­i­mal trade

Live an­i­mals are rou­tinely trans­ported by road, rail, sea, or air across differ­ent coun­tries and con­ti­nents. Ac­cord­ing to CIWF, trans­ported an­i­mals suffer from over­crowd­ing, ex­haus­tion, de­hy­dra­tion, ex­treme tem­per­a­tures, and other prob­lems. Ac­cord­ing to RSPCA, they also suffer from in­juries due to in­ap­pro­pri­ate han­dling, in­ap­pro­pri­ate ve­hi­cles, men­tal dis­tress due to un­usual and po­ten­tially fright­en­ing sights, move­ments, noises, smells, un­fa­mil­iar an­i­mals and stock­per­sons. Fur­ther­more, live an­i­mal trade can spread dis­eases across the globe.

In this page, FAOSTAT pro­vides es­ti­mates of num­bers of an­i­mals ex­ported/​im­ported al­ive by each coun­try. In the table be­low, I pre­sent com­bined live im­port and ex­port data for all coun­tries in 2017:

table

Sources and rea­sons for im­port-ex­port in­con­sis­ten­cies are ex­plained by FAO here. Note that the num­bers of an­i­mals traded live are ris­ing. Also note that some an­i­mals who are not traded be­tween coun­tries can still be live-trans­ported long dis­tances within a coun­try. For ex­am­ple, CIWF claims that cat­tle are trans­ported across In­dia and farm an­i­mals are trans­ported for thou­sands of miles within Canada. Fi­nally, note that these num­bers ex­clude live-traded fish, pets, and other an­i­mals.

Chickens

Chick­ens in the egg industry

Ac­cord­ing to FAOSTAT data, there were 7.5B egg-lay­ing hens in the world in 2018. How­ever, I no­ticed in­con­sis­ten­cies in the FAOSTAT data, which led me to be­lieve that this num­ber is in­ac­cu­rate. For ex­am­ple, FAO statis­tics for the UK seem to in­clude not only lay­ers but also pul­lets (hens who are too young to lay eggs) and roost­ers (who are used for breed­ing hens). FAO statis­tics for the U.S. in­clude lay­ers, but not pul­lets or roost­ers (see Šimčikas (2019a)). If all coun­tries re­ported hen num­bers in the way U.S. did, the to­tal num­ber of chick­ens in­volved in egg pro­duc­tion globally would in­crease from 7.5B to roughly 10.3B.[14] Since it seems that differ­ent coun­tries re­ported the data in differ­ent ways, I think that most likely, the real num­ber is be­tween 7.5B and 10.3B.

Note that this in­cludes 390M–670M moth­ers and fathers of meat chicken (es­ti­mated in one of the sec­tions be­low). If we ex­clude them, we get that there are 6.8B–9.9B chick­ens in­volved in the pro­duc­tion of eggs for con­sump­tion.

Ac­cord­ing to FAOSTAT, about 39.1% of the wor­lds egg-lay­ing hens (in­clud­ing moth­ers and fathers of meat chicken) are in China, 25.8% in other Asian coun­tries, 10.8% in Europe, 7.7% in South Amer­ica, 6.9% in Africa, 5.7% in North Amer­ica, and 3.3% in Cen­tral Amer­ica.

Chick­ens bred for meat (broilers)

Ac­cord­ing to FAOSTAT, there were 23.7B chick­ens al­ive in cap­tivity in 2018. Also, in the sec­tion above, I ex­plained that there are 7.5B–10.3B chick­ens used in the egg-lay­ing in­dus­try. It would fol­low that there are 13.4B–16.2B chick­ens raised for meat at any time. Per­haps even more be­cause some chick­ens are raised for both meat and eggs. How­ever, ac­cord­ing to a rough es­ti­mate in an Open Phil spread­sheet (Broilers (2017) tab), there are 9.55B meat chick­ens in the world. I’m un­sure which es­ti­mate is more ac­cu­rate. Hence, I think that the num­ber of meat chick­ens in the world is in the range of 9.5B–16.2B.

Meat chicken moth­ers and fathers (broiler breed­ers)

The es­ti­mate of meat chick­ens above ex­cludes their moth­ers. They are hens who lay eggs that hatch into meat chick­ens. Th­ese hens might be suffer­ing even more than meat chick­ens be­cause they are kept hun­gry all the time to avoid gain­ing ex­ces­sive weight (see Sethu (2014)).

I haven’t found a de­pend­able es­ti­mate of how many meat chicken moth­ers there are in the world. I tried to ex­trap­o­late it based on statis­tics for var­i­ous years and re­gions (U.S., UK, EU, South Africa, Brazil, Pak­istan). Ac­cord­ing to most of my ex­trap­o­la­tions, there are 350M–600M meat chicken moth­ers in the world. All ex­trap­o­la­tions can be seen in this spread­sheet. They in­volved some sim­plifi­ca­tions[15], but I think that the re­sult should be roughly cor­rect.

I also es­ti­mate[16] that there are roughly 40M–70M meat chicken fathers in the world. I don’t know if they face similar welfare is­sues to moth­ers.

Cul­led male chicks

In the egg in­dus­try, male chicks are usu­ally cul­led (slaugh­tered) at a very young age (e.g., one day) be­cause they can not lay eggs and are less suit­able for meat pro­duc­tion than meat chicken breeds. It seems that they are ex­cluded from the FAOSTAT slaugh­ter to­tals.

CIWF (2015) claims that 5B male chicks are cul­led per year. Flem­ing (2016) claims that it’s 3.2B. WATTAgNet (2018) claims that it’s 6B. Kraut­wald-Jung­hanns et al. (2018) and Vo­gel (2019) claim that it’s 7B. None of these sources ex­plain how they at­tained these figures, and I don’t know if any of the au­thors made de­tailed es­ti­ma­tions. Note that the num­ber of egg-lay­ing hens al­ive at any time has been in­creas­ing, which may ex­plain why some ear­lier sources claim that the num­ber is lower.

Other birds

Quail

Quail are small birds who are farmed for their meat and eggs. CIWF claims that the vast ma­jor­ity of quail are farmed in­ten­sively in bat­tery cages or over­crowded barns.

quail

Quail farm­ing. A photo from Tas­nim News Agency.

I haven’t found any re­li­able es­ti­mates of the num­ber of quail farmed in the world. Chang et al. (2007) and Xu et al. (2003) claim that there are about 1B quail around the world, but the source for the claims is un­clear. Ac­cord­ing to Table 1 in Min­vielle (2004), there are 169M Ja­panese quail slaugh­tered for meat and al­most 11B quail eggs pro­duced (pre­sum­ably per year). How­ever, the pa­per claims that figures lack pre­ci­sion. Fur­ther­more, the pa­per uses some sources that date back to 1991.[17]

Ac­cord­ing to da Cunha (2009), by far the biggest quail pro­ducer is China. The ar­ti­cle claims there were about 80M quail housed ex­clu­sively for meat and 270M–300M quail kept for egg pro­duc­tion at the time of writ­ing the ar­ti­cle in 2009. From this, the ar­ti­cle es­ti­mates that 1.3B–1.7B quail are slaugh­tered for meat in China ev­ery year (in­clud­ing 315M–350M egg-lay­ers slaugh­tered af­ter their pro­duc­tive pe­riod). The num­bers now could be even higher since the ar­ti­cle claims that there were per­spec­tives for an in­crease in the quail egg pro­duc­tion.

Other coun­tries with sig­nifi­cant quail pro­duc­tion in­clude:

  • Brazil. Ac­cord­ing to figure 1 in Berte­chini (2012), around 18M quail were housed in Brazil in 2012. The ar­ti­cle pre­dicts that in 2020, 36M quail will be housed in the coun­try. It seems that most of these quail are raised pri­mar­ily for eggs.

  • U.S. Ac­cord­ing to table 30 in the 2018 Cen­sus of Agri­cul­ture, in 2017, there were 7.4M quail farmed in the U.S. at any time and about 23M quail were “sold”.

  • Spain. Ac­cord­ing to da Cunha (2009), in 2004, Spain pro­duced an es­ti­mated 9,300 tonnes of quail meat. In es­ti­ma­tions for China, da Cunha (2009) as­sumes an av­er­age car­cass yield of 140g. If this is roughly true for Spain’s pro­duc­tion as well, it fol­lows that about 66M quail were slaugh­tered in Spain in 2004. As­sum­ing slaugh­ter age of 5 weeks, that’s about 6M quail raised for meat at any time.

  • France. Ac­cord­ing to offi­cial statis­tics, 38M quail were slaugh­tered for meat in 2008. As­sum­ing slaugh­ter age of 5 weeks, that’s about 3.6M quail raised for meat at any time. The source also claims that 83M quail eggs were pro­duced in 2008. As­sum­ing 230 eggs per year per bird, there were roughly 0.36M lay­ing quail in the coun­try.

  • Italy. Ac­cord­ing to da Cunha (2009), 20M–28.5M quail are slaugh­tered in Italy ev­ery year. As­sum­ing slaugh­ter age of 5 weeks, that’s about 1.9M–2.7M quail raised for meat at any time.

If we add up these num­bers,[18] we get that these coun­tries slaugh­ter about 200M quail an­nu­ally and house very roughly 55M quail at any time. If we add this to the es­ti­mates for China, we get that there are roughly 420M quail housed at any time, and 1.5B–1.9B quail slaugh­tered an­nu­ally.

Th­ese es­ti­mates seem to ex­clude breed­ers (quail moth­ers and fathers) and hens who are too young to lay eggs. Fur­ther­more, they ex­clude quail raised in other coun­tries. Ac­cord­ing to Berte­chini (2012), the only ma­jor quail pro­ducer that the list above ex­cludes is Ja­pan.

If I ac­count for breed­ers, mor­tal­ity, and other coun­tries, my best guess is that there are about 400M–550M quail farmed in the world, and that 1.5B–2.5B quail are slaugh­tered an­nu­ally. How­ever, these es­ti­mates are mostly based on old statis­tics, and I’m un­sure how de­pend­able the sources are.

I don’t un­der­stand why there is no cat­e­gory for quail in FAOSTAT. Per­haps some of the birds cat­e­go­rized as “Bird, meat, not speci­fied” and “Egg, other bird” are quail. How­ever, it seems that there are many more quail than birds in these cat­e­gories. FAO claim that “[c]er­tain other coun­tries give a sin­gle figure for all poul­try; data for these coun­tries are shown un­der “Chick­ens”.” Hence, it’s also pos­si­ble that some of the chick­ens in the FAO statis­tics are ac­tu­ally quail.

Foie gras

Foie gras is a spe­cialty food product made of the liver of a duck or goose. The pro­duc­tion of foie gras usu­ally in­volves fat­ten­ing birds by force-feed­ing them with a tube. Some an­i­mal ad­vo­cates fo­cus on fight­ing against this prac­tice due to its cru­elty.

Ac­cord­ing to Willsher (2012), France is re­spon­si­ble for 75% of the world’s foie gras pro­duc­tion and slaugh­ters around 38M ducks and geese for this pur­pose ev­ery year. It fol­lows that around 38M /​ 0.75 = 50.7M ducks and geese were slaugh­tered for foie gras ev­ery year globally. How­ever, the source of Willsher (2012) num­bers is un­clear and could be out­dated. Note that, in some coun­tries (but not France), foie gras could be pro­duced us­ing nat­u­ral feed­ing.

Euro Foie Gras claims that in 2018, the EU pro­duced ap­prox­i­mately 22,600 tonnes of duck foie gras and 1,900 tonnes of goose foie gras and that this is about 90% of the world’s pro­duc­tion. Nis­tor et al. (2005) claims that duck foie gras weighs 350 g to 600 g on av­er­age and goose foie gras weighs 600 g to 800 g on av­er­age. Us­ing this in­for­ma­tion, I roughly es­ti­mated that 45M–64M ducks and geese were slaugh­tered for foie gras globally in 2018.

Ac­cord­ing to an archived fact­sheet from Viva!, “Ducks are typ­i­cally slaugh­tered at 100 days and geese at 112 days.” Similar slaugh­ter ages can be de­duced from other sources. It fol­lows that there are roughly 11M–19M birds al­ive at any time for foie gras pro­duc­tion. This es­ti­ma­tion ex­cludes breed­ers and birds who die be­fore slaugh­ter.

Another rele­vant statis­tic from the Viva! spread­sheet is that ducks are force-fed twice a day for 12.5 days and geese three times a day for around 17 days. Similar figures are given by other sources. If we as­sume that 92%–100% of the 45M–64M birds are force-fed, we get that roughly 1.4M–2.3M ducks and geese are in the force-feed­ing pe­riod at any point in time.

All the es­ti­ma­tions can be found in this Guessti­mate model. Note that even though I use Guessti­mate, my re­sults are not a 90% sub­jec­tive con­fi­dence in­ter­vals. I’m un­sure how re­li­able the in­for­ma­tion in used sources is.

Down

Waterfowl (mainly ducks and geese) have a layer of down feathers clos­est to the skin, which are sought af­ter for use in bed­ding and out­door cloth­ing. I was un­able to es­ti­mate how many birds were plucked for their down.[19] How­ever, ac­cord­ing to FAOSTAT, in 2017, there were es­ti­mated 371M geese and guinea fowl and 1.2B ducks al­ive in cap­tivity at any given time in the world. A large pro­por­tion of them are reared for meat pro­duc­tion, with down and feathers be­ing a valuable byproduct, as illus­trated by the in­dus­try sizes. Ac­cord­ing to In­dexBox (2019), the global duck and goose meat mar­ket rev­enue amounted to $19B in 2018. Com­par­a­tively, ac­cord­ing to Profshare (2017), the down feather mar­ket was val­ued at $5.9B in 2017, and is ex­pected to reach $10.25B by the end of 2025.

Some geese and ducks are plucked for their down while they are still al­ive. PETA claims this in­volves sub­stan­tial pain and dis­tress for birds, who have feathers ripped from their skin. The pro­por­tion of down that comes from live-plucked birds is un­clear. Kozak, Gara and Kawada (2010), claim that only 1–2% of to­tal goose feathers and down is sourced through live-pluck­ing. How­ever, they don’t provide any ex­pla­na­tion about how they ar­rived at this es­ti­mate. As the RSPCA ac­knowl­edges, statis­tics on the ex­tent of live-pluck­ing are lack­ing. Hen­driksz (2016) illus­trates that pluck­ing of­ten oc­curs ‘in se­cret’, de­spite reg­u­la­tions.

Note that buy­ing down can cause suffer­ing even if its pro­duc­tion doesn’t in­clude live-pluck­ing. It sup­ports meat and foie gras in­dus­tries as many farm­ers who raise birds for food make ex­tra rev­enue by sel­l­ing their feathers. Fur­ther­more, PETA claims that “many of these birds are im­prop­erly stunned, which means that they are still con­scious when their throats are cut and they are dumped into the scald­ing-hot wa­ter of the defeather­ing tank.”

Swiftlets

The swift­let farm­ing in­dus­try in­volves the har­vest­ing of ed­ible birds nests, which swiftlets con­struct from their sal­iva. The nests are then sold and eaten in an ex­pen­sive del­i­cacy, birds nest soup. They are also in­creas­ingly used within the beauty in­dus­try and el­se­where. De­mand is high­est in Asia, mainly China (Chua and Zukefli (2016)). My im­pres­sion is that swiftlets do not suffer as much in com­par­i­son to other farmed an­i­mals.[20] How­ever, this in­dus­try seems to be rapidly grow­ing, and I don’t know if farm­ing prac­tices will re­main as they are.

Mammals

Work­ing animals

The FAOSTAT statis­tics in­clude at least some of the work­ing an­i­mals that are used for tasks like pul­ling carts, plow­ing, trans­port­ing ma­te­ri­als and peo­ple, and other pur­poses.[21] Statis­tics usu­ally do not dis­t­in­guish for what pur­pose an­i­mals are used. Hence, it is very difficult to es­ti­mate the num­ber of work­ing an­i­mals in the world. Starkey (2010) claims:

There are few au­thor­i­ta­tive es­ti­mates of work an­i­mals: only some gov­ern­ments record their num­bers. Na­tional herd figures from FAOSTAT are good es­ti­mates for mules and don­keys which are kept for work. They are less re­li­able for horses and camels that may be kept for other pur­poses. Most cat­tle and buf­faloes are main­tained for meat or milk and these species re­quire sur­vey data to gauge work­ing uses. Un­sub­stan­ti­ated es­ti­mates pre­pared around 1980 sug­gested 300-400 mil­lion work­ing an­i­mals in the world. Since then, num­bers in Africa have in­creased with sig­nifi­cant de­creases in some Asian coun­tries, no­tably China and Bangladesh. Cur­rent world use may be 200-250 mil­lion.

Other un­sub­stan­ti­ated es­ti­mates I found also vary be­tween 200M and 300M an­i­mals used for work, with one 1999 es­ti­mate claiming that it’s nearly 600M.[22] Note that in ad­di­tion to work­ing, these same an­i­mals may be used for milk, meat, wool, hair, off-springs, hides, horns, hooves, etc.

See Alves (2018) for a gen­eral overview of work­ing an­i­mals. It claims that de­spite the ad­vances of mech­a­niza­tion, the im­por­tance of work­ing an­i­mals as a source of power is likely to con­tinue in the fore­see­able fu­ture.

There are many se­ri­ous con­cerns about the welfare of work­ing an­i­mals, es­pe­cially in de­vel­op­ing coun­tries. They suffer from over­work, poor nu­tri­tion, in­ad­e­quate ba­sic health care, bad treat­ment by the own­ers, lack of wa­ter, in­ap­pro­pri­ate equip­ment, cruel prac­tices, etc. (see Rah­man and Kahn (2014), Yee (2016), wor­l­dan­i­mal.net overview)

working_animals

An­i­mals used for trans­port in Nepal. A photo by Gun­jan Raj Giri.

Purposes

Here is an in­com­plete list of cat­e­gories of work­ing an­i­mals:

Wor­l­dan­i­mal.net claims that “the ma­jor­ity of work­ing an­i­mals are in­volved in trans­port and agri­cul­ture.” An­i­mals used for work in­clude oxen, wa­ter buf­faloes, yaks, horses, asses, camels, mules, dogs, elephants, rein­deer, rats, and oth­ers.

Fur farming

Lung and Lin (2019) pro­vides es­ti­mates of how many minks, foxes, and rac­coon dogs are farmed in China, EU, USA, and Canada in 2016:

  • 71M minks (26.2M in China, 39M in Europe, 3.5M in the U.S. and 2.1M in Canada)

  • 15M foxes (12.6M in China, 2.7M in Europe)

  • 15M rac­coon dogs (al­most all in China)

In to­tal, that’s about 100M. My im­pres­sion is that this cov­ers most of the an­i­mals farmed for fur. How­ever, this num­ber ex­cludes some an­i­mal species and coun­tries. It also seems to ex­clude trapped an­i­mals. TruthAboutFur.com (a pro-fur web­site) claims that wor­ld­wide, about 85% of the furs pro­duced come from farmed an­i­mals. The rest comes from trapped an­i­mals. The web­site also claims that farmed an­i­mals are “pri­mar­ily mink and fox, but also chin­chilla, Finn rac­coon (Asi­atic rac­coon), sable, Rex rab­bit, Karakul sheep and other species.”

Open Phil (2019) com­bined in­for­ma­tion from mul­ti­ple sources and es­ti­mated that about 60M mink were farmed globally in 2018, down from more than 100M in 2015. The ar­ti­cle also es­ti­mates that “about 45M an­i­mals are suffer­ing on fur farms at any time.” How­ever, they do not provide the de­tails of their es­ti­mate.

Hansen (2017) claims that the 2015 fur pro­duc­tion is in the or­der of 85M mink furs and 95M furs in to­tal.

Rabbits

Many web­sites claim that over one billion an­i­mals are kil­led for fur ev­ery year (e.g. 1, 2, 3). PETA’s page about fur cites Le­bas et al. (1997) as the source for the same claim. Le­bas et al. (1997) have the fol­low­ing ex­cerpt, which might be the base for all of these claims:

“Mink, which tops the list of species bred es­sen­tially for its fur, sup­plies a world to­tal of about 25 mil­lion to 35 mil­lion pelts a year whereas rab­bit pelts are es­ti­mated at one billion.”

How­ever, in the same sec­tion, Le­bas et al. (1997) call rab­bit skin a by-product of meat and claim that most rab­bit skins are thrown away. Hence, it seems that the claim that PETA and other web­sites make is in­ac­cu­rate. Ac­cord­ing to FAOSTAT, there were 564M rab­bits slaugh­tered for meat in 1997, which makes the one billion figure from Le­bas et al. (1997) sur­pris­ing. In 2018 there were 922M rab­bits slaugh­tered.

Open Philan­thropy Pro­ject (2019) claims that rab­bits are farmed mostly for their meat, but some are farmed ex­clu­sively for their fur. Lung and Lin (2019) claims that:

It is es­ti­mated that tens of mil­lions of rex rab­bits are also used each year for their pelts, but be­cause these rab­bits are also used for their meat, it is difficult to sep­a­rate data from the two in­dus­tries and state which is the pri­mary pur­pose of breed­ing. Tak­ing pub­lished figures from 2011 to 2012 as an ex­am­ple, 130 mil­lion rex rab­bits were re­port­edly bred and pro­cessed into fur in China.

Ro­dents farmed for pet snake food

In Šimčikas (2019c), I es­ti­mated that 160M–2.1B ver­te­brates are kil­led for pet snake food ev­ery year. Most of the ver­te­brates seem to be mice that are usu­ally farmed in bad con­di­tions. Th­ese mice are kil­led when they are any­where be­tween 48 hours and more than 9 months old. Most seem to be slaugh­tered when they are 3–4 weeks old, al­though I’m un­cer­tain. As­sum­ing that the av­er­age farmed ro­dent lifes­pan is be­tween 1 week and 2 months, we can es­ti­mate that there are 3M–350M ro­dents farmed for pet snake food at any one time.

Farm­ing of feeder ro­dents seems to in­volve con­sid­er­able suffer­ing be­cause they are of­ten kept in cramped and pos­si­bly un­san­i­tary con­di­tions, lack shelters, daylight, and ac­tivi­ties. See Šimčikas (2019c) for a gen­eral overview of the is­sue.

Ro­dents bred for hu­man consumption

Ac­cord­ing to Gru­ber (2016), rats are “a reg­u­lar sta­ple” in many coun­tries in South East Asia. It also claims that ro­dents are eaten in Africa, South and Cen­tral Amer­ica. It seems that many of the ro­dents eaten are caught from the wild rather than farmed (see Gru­ber (2016), Dell’Amore (2019)). How­ever, Gru­ber (2016) also claims that “some ex­perts sug­gest that farm­ing and eat­ing ro­dents could be one solu­tion for alle­vi­at­ing the world’s hunger and malnu­tri­tion prob­lems.”

Ac­cord­ing to FAOSTAT, in 2018, there were 71.3M ro­dents slaugh­tered in the world, and there 19.2M farmed ro­dents al­ive at any time,[23] all in Peru and Bo­livia. Th­ese stats seem to be some­what in­com­plete be­cause they ex­clude Africa. Jori et al. (2005) claims that ro­dent farm­ing is “slowly de­vel­op­ing in some parts of Africa” but “ro­dent farm­ing pro­jects are not the panacea and many prob­lems still need to be solved to reach a large scale pro­duc­tion”. Maass et al. (2014) claims that more than 2M cavies are already kept in DRC and sug­gest that cavy cul­ture in DRC is likely to be­come more wide­spread. Maass (2019) claims that guinea pigs are farmed in many other Afri­can coun­tries (Benin, Cameroon, Côte d’Ivoire, Ghana, Kenya, Nige­ria, Tan­za­nia, and Togo). It also claims that they are pre­dom­i­nantly kept in houses or kitchens and are not in­cluded in most na­tional statis­tics.

Edit April 27th, 2020: Thom­son (2020) claims that Chi­nese farm­ers were rear­ing about 25M bam­boo rats when the gov­ern­ment launched a ban on the trad­ing and con­sump­tion of wild an­i­mals in the wake of the COVID-19 out­break. Ac­cord­ing to Thom­son (2020), “the pos­si­bil­ity of bam­boo rats be­ing al­lowed back on the din­ner plate would be slim.” The ban prob­a­bly also im­pacts some other groups of an­i­mals that are de­scribed in this ar­ti­cle. How­ever, Wald­horn (2020) claims that “it is known that law en­force­ment, es­pe­cially re­gard­ing an­i­mals, can be a prob­lem in the re­gion. Ad­di­tion­ally, due to the size of the mar­ket, if a ban is not ad­e­quately man­aged, it can lead to an ex­plo­sion of a black mar­ket for an­i­mals. ”

Dogs and cats kil­led for meat and fur

Ac­cord­ing to HSI, 30M dogs and 10M cats are kil­led an­nu­ally for hu­man con­sump­tion across Asia and that there are thou­sands of dog meat farms in South Korea. Ac­cord­ing to An­i­malsAsia, 10M dogs and 4M cats, are slaugh­tered for meat in China. None of these es­ti­mates are sub­stan­ti­ated.

ACTAsia for An­i­mals (2017) claims that there are many dog farms in China and that cat breed­ing farms are less com­mon. It also claims that dogs and cats (in­clud­ing fam­ily pets) are of­ten taken from streets in or­der to be slaugh­tered. It’s also sus­pected that some slaugh­tered dogs come from over­crowded dog shelters.

Slaugh­tered dogs and cats are used for meat and fur. In­ter­nal dog or­gans are also used in tra­di­tional Chi­nese medicine (ACTAsia for An­i­mals (2017)).

Puppy mills/​farms

Puppy mills are defined as dog breed­ing op­er­a­tions in which the health of dogs is dis­re­garded in or­der to main­tain a low over­head and max­i­mize prof­its.

  • U.S. HSUS (2019) claims that es­ti­mated 2.4M pup­pies who origi­nated from puppy mills are sold in the U.S. an­nu­ally. About half of them were raised in USDA-li­censed fa­cil­ities. About 200,000 dogs were kept solely for breed­ing pur­poses in USDA-li­censed fa­cil­ities. HSUS web­site pro­vides more in­for­ma­tion on the topic.

  • UK. Na­ture­watch claims that “up to 400,000 farmed pup­pies are sold to the Bri­tish pub­lic ev­ery year.” El­got (2019) de­scribes a re­cently-passed law that may help to de­crease the scale of the prob­lem in the coun­try.

None of these sources fully ex­plain how they ar­rived at these num­bers. As I un­der­stand it, these are only es­ti­mates of dogs bred in bad con­di­tions. The to­tal num­ber of dogs in breed­ing fa­cil­ities is prob­a­bly much higher. Hughes and Mac­don­ald (2013) es­ti­mate that the global do­mes­tic dog pop­u­la­tion abun­dance is over 700M. It’s likely that a sig­nifi­cant pro­por­tion of them origi­nate from breed­ing op­er­a­tions.

It seems that puppy mills also ex­ist in coun­tries like China (Jones (2018)) and In­dia (Block (2018)). Since dogs are used as pets around the world, I ex­pect that puppy farms ex­ist in many other coun­tries as well.

Other pet mills

Similar to dogs, many other an­i­mals are some­times bred in bad con­di­tions to be sold as pets. An­i­mals Aus­tralia page and pet­ful.com ar­ti­cle de­scribe in­hu­mane con­di­tions in kit­ten mills. Schel­ling (2016) and HSUS (2019) de­scribe cruel con­di­tions in which rab­bits and ro­dents are raised to be sold to pet stores. I haven’t tried to find the num­ber of an­i­mals raised in these fa­cil­ities.

Dog and cat shelters

Ac­cord­ing to the ASPCA, ap­prox­i­mately 3.3M dogs and 3.2M cats en­ter U.S. pet shelters ev­ery year. After a brief search, I failed to find statis­tics for other coun­tries or how many an­i­mals are al­ive in the U.S. pet shelters at any time.

Deer farming

Ac­cord­ing to the offi­cial New Zealand statis­tics, there were 851,000 farmed deer in the coun­try in 2018. Ac­cord­ing to Table 32 in the 2017 U.S. Cen­sus of Agri­cul­ture, there were 212,449 deer in cap­tivity in the U.S. in 2017. Vege­tar­ian so­ciety claims that “4,612 farmed deer were slaugh­tered for their meat (veni­son) in the UK in 2010.”

Bullfighting

HSI claims that “ev­ery year, ap­prox­i­mately 250,000 bulls are kil­led in bul­lfights.” The same claim is made by WAP. PETA also used to make the same claim but now PETA claims that “in 2018, at least 7,000 bulls were kil­led in offi­cial bul­lfights in Spain.” It also claims that “the num­ber of bulls kil­led has been de­creas­ing since 2007.” CAS In­ter­na­tional claims that “it is es­ti­mated that wor­ld­wide more than 180,000 bulls, cows and calves are abused and slain dur­ing bul­lfights and similar events ev­ery year.” Note that the num­ber of an­i­mals used in bul­lfight­ing may be much big­ger than the num­ber kil­led. A lot of statis­tics on bul­lfight­ing in Spain and some other coun­tries are an­a­lyzed in AVATMA (2018). It claims that the data on bul­lfight­ing is con­tra­dic­tory. My im­pres­sion is that the num­ber of an­i­mals kil­led in bul­lfights is much smaller than 250,000, but I’m not con­fi­dent.

Horses kept for recre­ation, com­pe­ti­tion, and racing

There are nu­mer­ous horse-re­lated ac­tivi­ties listed here. Ac­cord­ing to Ross (2019), in the U.S. alone, there are 3.1M used for recre­ation, 1.2M for com­pe­ti­tion, 1.2M for rac­ing, and 1.5M used for other pur­poses. How­ever, the ar­ti­cle doesn’t provide a source for these num­bers.

Thor­ough­bred horse racing

Ac­cord­ing to McManus, Albrecht and Gra­ham (2012), in ex­cess of 110,000 thor­ough­bred horses are born each year through­out the world. Only 5% to 10% ever see a race­course ac­cord­ing to The Horse Fund. Tens of thou­sands are slaugh­tered an­nu­ally due to over­breed­ing (PETA), with oth­ers be­ing used for pur­poses other than rac­ing.

McManus, Albrecht and Gra­ham (2012) claims that in 2009 there were 162,891 thor­ough­bred horse races held in 47 coun­tries, with over 250,000 horses start­ing a race. This figure of 250,000 ex­cludes fe­males, foals or sires (males kept for breed­ing pur­poses); only race­horses, typ­i­cally 1–2 years of age. There­fore, the ac­tual figure for the num­ber of thor­ough­breds kept in cap­tivity at any given time is likely to be mul­ti­ple times higher. Ross (2019) claims that there are 1.1M thor­ough­bred horses in the U.S. alone.

Grey­hound racing

Ac­cord­ing to GREY2K USA wor­ld­wide (2019), com­mer­cial grey­hound rac­ing ex­ists in seven coun­tries at nearly 150 tracks wor­ld­wide. The ar­ti­cle claims that each year, the grey­hound in­dus­try wor­ld­wide breeds at least 48,000 grey­hound pups. Ac­cord­ing to the ar­ti­cle, the grey­hound rac­ing in­dus­try has rapidly de­clined by over 70% over the last ten years, and this trend is ex­pected to con­tinue.

Bear farming

Bears are kept in cap­tivity to har­vest their bile, a di­ges­tive fluid pro­duced which is used in tra­di­tional Chi­nese medicine. Ac­cord­ing to Black (2007), re­searchers be­lieve that more than 12,000 bears were kept on farms in China, Viet­nam, and South Korea in 2007. WAP claims that there are up to 20,000 bears farmed across Asia but doesn’t provide a source for the claim. An­i­mals Asia (2019) de­scribes cruel con­di­tions in which bears are farmed.

Lion and tiger farming

Ac­cord­ing to World An­i­mal Pro­tec­tion (2019), 12,000–17,000 li­ons and tigers are raised in harsh cap­tive con­di­tions to be used for tra­di­tional Asian medicine prod­ucts. In some cases, they are also used for tourism ex­pe­riences. Most big cat breed­ers are in China and South Africa. World An­i­mal Pro­tec­tion (2014) claims that there are also 5,000 cap­tive tigers in the U.S., pre­sum­ably mostly used as a tourist at­trac­tion. Note that many an­i­mals may be kil­led to feed these car­nivores.

Civet farming

Ac­cord­ing to wor­l­dan­i­mal.net, ap­prox­i­mately 3,000 civets are kept in prim­i­tive con­di­tions on over 200 farms in Ethiopia. They are farmed for musk, which is used in per­fumes by sev­eral per­fumeries in France.

Civets are also kept in cap­tivity to pro­duce civet coffee. This coffee in­cludes par­tially di­gested coffee cher­ries, eaten and defe­cated by the Asian palm civet. I haven’t seen any es­ti­mates of how many civets are kept in cap­tivity for this pur­pose.

Mixed species

Tay­lor et al. (2008) con­ser­va­tively es­ti­mated that in 2005 there were 58M ver­te­brates used in re­search wor­ld­wide and 57M used for re­search-re­lated pur­poses. In to­tal, that’s 115M an­i­mals. In this con­text, re­search-re­lated pur­poses are:

  • kil­ling an­i­mals only for tis­sue sup­ply,

  • us­ing an­i­mals to main­tain ge­net­i­cally mod­ified breed­ing colonies,

  • breed­ing an­i­mals for lab­o­ra­tory use but kil­ling them with­out ex­per­i­men­ta­tion be­cause they are sur­plus to re­quire­ments.

Knight (2008) an­a­lyzed the data of Tay­lor et al. (2008) and sug­gested that the figure should be 127M rather than 115M. Knight (2008) still con­sid­ered the es­ti­mate to be con­ser­va­tive and far from pre­cise. Lush Prize (2014) up­dated Tay­lor et al. (2008) and es­ti­mated that in 2012 the num­ber of an­i­mals used in re­search (in­clud­ing re­search-re­lated uses) was 118M.

Cru­elty Free In­ter­na­tional claims that “an­i­mal ex­per­i­ments are sadly not in de­cline, and in many parts of the world are on the in­crease (e.g. China) or re­main at the same level as they were in the 1980s or 1990s (e.g. the UK, Europe).” Fau­n­a­lyt­ics’ sum­mary of Cao (2018) claims that “each year, Chi­nese lab­o­ra­to­ries use 12-13 mil­lion an­i­mals in re­search”. This is much more that Tay­lor et al. (2008) es­ti­mate for China which is 3M.

U.S.

Tay­lor et al. (2008) roughly es­ti­mates that there are 17.3M an­i­mals used for re­search in the U.S. How­ever, it also notes that the num­ber could be much big­ger. USDA (2000) de­scribes a sur­vey of 50 of 2,000 U.S. re­search in­sti­tu­tions. Com­bined, these 50 in­sti­tu­tions re­ported us­ing 0.25M–1M rats, 0.4M–2M mice, and 0.13M–0.9M birds. From this, Tay­lor et al. (2008) ex­trap­o­lates that there are 31–156M an­i­mals used for re­search-re­lated pur­poses in the U.S. alone, and con­cludes that its 115M figure may be “a sub­stan­tial un­der­es­ti­mate”.

USDA (2000) also claims that it is es­ti­mated that more than 500M rats, mice, and birds are used in re­search, breed­ing, ex­hi­bi­tion, and trans­port in the U.S. but doesn’t ex­plain the es­ti­mate.[24]

Good­man, Chandna, and Roe (2015) claim that the num­ber of an­i­mals used for re­search in the U.S. has in­creased sig­nifi­cantly be­tween 1997 and 2012.

An­i­mals dis­sected in classrooms

Es­ti­mates of an­i­mals used for re­search pur­poses don’t seem to in­clude an­i­mals dis­sected in class­rooms. Na­tional Anti-Vivi­sec­tion So­ciety claims that es­ti­mated 6M–12M an­i­mals of var­i­ous species are ei­ther “pur­pose bred” or har­vested from the wild for use as dis­sec­tion spec­i­mens in the U.S. Similarly, PETA claims that in the U.S., es­ti­mated 20M an­i­mals are used for teach­ing ex­er­cises an­nu­ally, and that about 10M of them are dis­sected in class­rooms. An­i­mals are also dis­sected in class­rooms in the UK and prob­a­bly in many other coun­tries. Hence, wor­ld­wide num­bers could be mul­ti­ple times higher.

Na­tional Anti-Vivi­sec­tion So­ciety also claims that dis­sec­tion teaches stu­dents that an­i­mal lives have lit­tle im­por­tance and that it is not needed for teach­ing be­cause “nu­mer­ous stud­ies have re­ported that stu­dents who uti­lize hu­mane al­ter­na­tives to dis­sec­tion score as well or bet­ter on perfor­mance tests than stu­dents who par­ti­ci­pate in dis­sec­tion.”

Sel­ling live food animals

In some parts of the world, all kinds of live an­i­mals are held al­ive in wet mar­kets and butchered be­fore the sale or sold al­ive to cus­tomers. The prac­tice has re­cently re­ceived a lot of main­stream pub­lic­ity be­cause it is linked to out­breaks of new hu­man viruses. In ad­di­tion to in­creas­ing the risk of pan­demics, the prac­tice also seems bad from an an­i­mal welfare per­spec­tive. From pic­tures I’ve seen, it seems that these an­i­mals are usu­ally kept in bad con­di­tions. In ad­di­tion, an­i­mals may also suffer when they are trans­ported to mar­kets and from mar­kets to house­holds. I think that fight­ing against the sel­l­ing live an­i­mals for food could also help with the moral cir­cle ex­pan­sion be­cause the prac­tice could be mak­ing peo­ple in mar­kets more ac­cus­tomed and numb to an­i­mal cru­elty.

I haven’t found any figures for the num­ber of an­i­mals that are kept al­ive in mar­kets. Re­gard­ing the sale of live fish, page 48 in FAO’s SOFIA 2018 re­port claims that:

Live fish is prin­ci­pally ap­pre­ci­ated in east­ern and south­east­ern Asia (es­pe­cially by the Chi­nese pop­u­la­tion) and in niche mar­kets in other coun­tries, mainly among im­mi­grant Asian com­mu­ni­ties. Com­mer­cial­iza­tion of live fish has grown in re­cent years as a re­sult of tech­nolog­i­cal de­vel­op­ments, im­proved lo­gis­tics and in­creased de­mand.

The re­port also claims that 45% of fish are uti­lized as “Live, fresh, or chilled”. Based on this, I sus­pect that the num­ber of fish suffer­ing in mar­kets could be very sig­nifi­cant. From videos I’ve seen, it seems that fish in wet mar­kets are held in very bad con­di­tions. How­ever, I’m un­sure if fish in these videos are ac­tu­ally al­ive, or if their bod­ies are mov­ing de­spite their brains be­ing dead.

In ad­di­tion to wet mar­kets, fish are also some­times sold in su­per­mar­kets where they can also be kept in bad con­di­tions (e.g., see this video). In Poland, Lithua­nia, and prob­a­bly some other coun­tries, some an­i­mal or­ga­ni­za­tions have ad­dressed this prob­lem.

An­i­mals bred to be hunted

In some coun­tries, an­i­mals are bred to stock ar­eas for hunt­ing. This is called game farm­ing. The scale of game farm­ing seems to be sig­nifi­cant:

  • UK. An­i­malAid claims that ev­ery year in Bri­tain, around 50M pheas­ants and par­tridge are mass-pro­duced in cages, hatcheries, sheds and pens so that they can be shot down by peo­ple as a sport. Similarly, ac­cord­ing to table 2 in Ae­bischer (2019), about 39M57M pheas­ants and 8.2M13.4M par­tridges were re­leased in the UK in 2016. It also men­tions that mal­lards are also re­leased but the num­ber is not re­ported. Some other sources claim that around 35M birds are re­leased in Bri­tain an­nu­ally but don’t provide an ex­pla­na­tion for their claims.[25]

  • U.S. Ac­cord­ing to this video, some of the pheas­ants are re­leased for hunt­ing in the U.S., while oth­ers are slaugh­tered for meat. Ac­cord­ing to the table 30 of 2017 U.S. Agri­cul­ture cen­sus, there were 2.5M pheas­ants farmed in the U.S. at any time. The table also shows that there are 0.8M chukars farmed in the U.S. and they also seem to be farmed to be hunted.

  • South Africa. Con­trary to Bri­tain and the U.S., South Africa’s game farms seem to mostly raise big mam­mals. Ac­cord­ing to Dall (2019), there are around 12,000 game ranches in South Africa. Ac­cord­ing to this pre­sen­ta­tion, there were fewer than 400,000 mam­mals in pri­vate game farms in 2015. I’m un­sure if this in­cludes all the an­i­mals be­cause if both statis­tics are cor­rect, there would be only 400,000 /​ 12,000 = 33 an­i­mals per farm. van der Merwe (2016) claims that there are an es­ti­mated 8,000 li­ons in South Africa’s game farms.

An­i­mals are also raised in game farms in France, Namibia, Kenya and prob­a­bly many other coun­tries. In Aus­tria, an­i­mal ac­tivists have achieved a ban on the hunt­ing of bred an­i­mals in en­clo­sures.

Mercy re­leases (fang­sheng)

Mercy re­lease (also known as fang­sheng, live re­lease, and prayer an­i­mal re­lease) is an old Bud­dhist tra­di­tion of re­leas­ing cap­tive an­i­mals to demon­strate com­pas­sion, cre­ate good for­tune, and earn merit. Prac­ti­tion­ers may think that they are do­ing an­i­mals a fa­vor by re­leas­ing them and sav­ing them from slaugh­ter. How­ever, HSI (2009) claims that the vast ma­jor­ity of an­i­mals used in mercy re­lease were cap­tured for the sole pur­pose of be­ing re­leased. It also claims that these an­i­mals are of­ten in­jured dur­ing trap­ping, may starve or suffo­cate dur­ing trans­port, and when they’re kept in crates for days or weeks. Re­leased an­i­mals of­ten fail to sur­vive due to in­juries or be­ing re­leased into the wrong habitats. The ones who sur­vive some­times be­come in­va­sive species and cause prob­lems for na­tive species (Ever­ard et al. (2019)). Aiy­ing (2018) de­scribes the prac­tice in China and claims that most re­leased an­i­mals there are cap­tive-bred and thus can’t sur­vive in the wild. Many are also caught again soon af­ter the re­lease and then re­sold for an­other re­lease.

HSI and some other an­i­mal char­i­ties are (or were) work­ing to ed­u­cate Bud­dhist about the harm­ful effects of mercy re­leases and lobby gov­ern­ment bod­ies to ban the prac­tice (see HSI (2013), Fal­coner (2009))

There seem to be no es­ti­mates of the num­ber of an­i­mals re­leased around the world. How­ever, some es­ti­mates sug­gest that the num­bers could be sig­nifi­cant:

  • Gilbert et al. (2012) es­ti­mated that over a 13 months pe­riod, 0.7M birds were sold for mercy re­lease in two ob­served sites in Ph­nom Penh, Cam­bo­dia. The ar­ti­cle also claims that Chan (2006) es­ti­mated an­nual sales of 0.7M–1M birds for re­lease in Hong Kong, but I wasn’t able to ver­ify the claim.

  • Some an­i­mal welfare groups claimed that 200M wild and cap­tive-bred an­i­mals are set free in Taiwan ev­ery year, rang­ing from in­sects to mon­keys (Ago­ramoor­thy and Hsu (2005), Fal­coner (2009)). How­ever, I haven’t found how this was es­ti­mated. Hence, I think this es­ti­mate should be given lit­tle weight.

Zoos

Frynta, Šimková, Lišková, & Lan­dová (2013):

Ac­cord­ing to the ISIS (In­ter­na­tional Species In­for­ma­tion Sys­tem) on­line database, more than 7 mil­lion in­di­vi­d­ual an­i­mals are kept in 872 zoos and aquar­iums (as recorded by the date of 12th Jan­uary 2011).

I wasn’t able to con­firm this claim. Fur­ther­more, Mucha (2017) claims that the same database con­tains in­for­ma­tion on 3.5M an­i­mals. The web­site of the database claims that they have in­for­ma­tion about 10M an­i­mals, “liv­ing and his­toric”. It could be that Frynta, Šimková, Lišková, & Lan­dová (2013) mis­tak­enly in­cluded his­toric an­i­mals in the 7M figure.

There are also some claims about the num­ber of an­i­mals in zoos by an­i­mal ad­vo­cacy or­ga­ni­za­tions, but they seem to be un­sub­stan­ti­ated. RSPCA claims that “600,000 birds and mam­mals are kept in the world’s zoos.” Free­dom For An­i­mals claims “at least 7,500 an­i­mals – and pos­si­bly as many as 200,000 – in Euro­pean zoos are ‘sur­plus’ at any one time” and that “an­i­mals are reg­u­larly ‘cul­led’ in UK zoos.”

Note that these num­bers don’t in­clude an­i­mals who are fed to car­nivorous zoo an­i­mals. Ac­cord­ing to a pri­vate con­ver­sa­tion with a former zoo em­ployee, some zoos raise mice and rats to feed their an­i­mals. Th­ese ro­dents may be kept in con­di­tions that are similar to con­di­tions of ro­dents farmed for pet snake food (de­scribed in Šimčikas (2019c)).

Circuses

Har­ris et al. (2006) claims that “there are be­tween 2,400 and 5,900 wild and do­mes­tic an­i­mals in cir­cuses in Europe.” Savonitto (2017) pro­vides num­bers of wild cir­cus an­i­mals in some coun­tries: more than 2,000 in Italy, more than 900 in Ger­many (ex­clud­ing camelids), 762 in Por­tu­gal. It also claims that there are 300 cir­cuses with wild an­i­mals in the EU, 205 of which are in Italy, Ger­many, or Por­tu­gal. I haven’t found num­bers for an­i­mals in cir­cuses in other parts of the world.

Other an­i­mals used for entertainment

Ac­cord­ing to World An­i­mal Pro­tec­tion (2014), there are:

  • around 16,000 Asian elephants in cap­tivity wor­ld­wide used for tourism rides and perfor­mances.

  • “1,600 or more” cap­tive bot­tlenose dolphins used for dolphin en­ter­tain­ment wor­ld­wide.

  • 3,000 baby macaques taken from the wild an­nu­ally to be used for perfor­mances.

There are many other en­ter­tain­ment-re­lated pur­poses for which an­i­mals are kept in cap­tivity that I haven’t tried to find es­ti­mates for. Here are links to Wikipe­dia ar­ti­cles about some of them:

There are also nu­mer­ous horse-re­lated ac­tivi­ties listed here.

Pets

While many peo­ple take good care of their pets, tech­ni­cally pets also live in cap­tivity. Hence, I in­cluded their num­bers in this ar­ti­cle as well.

Euromon­i­tor In­ter­na­tional has statis­tics on the num­ber of pets in 53 coun­tries[26], which ac­count for about 70% of the world’s hu­man pop­u­la­tion. The com­bined data from all of these coun­tries is sum­ma­rized in the table be­low. The dataset ex­cludes most Afri­can coun­tries, Pak­istan, Bangladesh, Myan­mar, and many smaller coun­tries. Statis­tics in the table be­low are pro­jec­tions based on a va­ri­ety of sources: pub­li­cly available data, ex­pert in­ter­views, gov­ern­ment statis­tics, etc.

table

I found sev­eral other sources about the num­ber of pets in var­i­ous re­gions. I sum­ma­rized them in the table be­low:

table

Sources claim that they con­ducted the fol­low­ing sur­veys to ar­rive at these es­ti­mates:

  • AVMA (2017) - a sur­vey of 50,000 pet-own­ing house­holds.

  • APPA (2018) - a sur­vey dis­tributed on­line to a na­tion­ally rep­re­sen­ta­tive sam­ple of 22,202 re­spon­dents from a panel. There are some is­sues with the method­ol­ogy used in APPA (2018) and AVMA (2017) that are re­viewed in Cud­ding­ton (2019). It sug­gests that APPA (2018) may have over­es­ti­mated pet num­bers.

  • PFMA (2019) - face-to-face in­ter­views of a rep­re­sen­ta­tive sam­ple of 8,000 re­spon­dents.

  • FEDIAF (2018) pro­vides es­ti­mates of the num­ber of pets in each Euro­pean coun­try. The doc­u­ment claims that “the figures are from FEDIAF and its mem­ber as­so­ci­a­tions, pet food com­pa­nies and es­ti­ma­tions based there­upon.” Num­bers for the UK seem to be based on PFMA (2019). I don’t know what the sources are for the figures for other coun­tries. The 300M figure for pet fish is only men­tioned in a foot­note, which sug­gests that this figure is less re­li­able.

  • AMA (2016) - a sur­vey of a rep­re­sen­ta­tive sam­ple of 2,022 Aus­trali­ans.

  • CAHI (2019) - a sur­vey of over 3,026 pet-own­ing households

  • 2019 Chi­nese Pet In­dus­try White Paper—I couldn’t ac­cess the pri­mary source. I took figures from ar­ti­cles cit­ing the white pa­per ([1], [2]). 2017 Chi­nese Pet In­dus­try White Paper es­ti­mated pet num­bers us­ing gov­ern­ment data and pet mar­ket re­search.

Most of these num­bers are similar to the ones pro­vided by Euromon­i­tor, and it is very likely that these sur­veys in­formed Euromon­i­tor pro­jec­tions. How­ever, the es­ti­mates of dog and cat in the 2019 Chi­nese Pet In­dus­try White Paper are much smaller than the es­ti­mates by Euromon­i­tor. Both sources agree that the Chi­nese pet pop­u­la­tion is grow­ing at a fast pace.

Coren (2012) es­ti­mates that “the best guess would be that there are at least 525 mil­lion dogs on our planet.” The es­ti­mate in­cludes some un­owned dogs but claims that it un­der­es­ti­mates their num­bers. How­ever, the ar­ti­cle doesn’t provide sources for its claims. The pro­vided num­bers for var­i­ous re­gions differ sig­nifi­cantly from the Euromon­i­tor data.

De Silva and Tur­chini (2008) es­ti­mate that in 2006 there were 167M do­mes­tic cats within the highly in­dus­tri­al­ized re­gions (USA, EU, Ja­pan, Canada, and Aus­trala­sia), 70M do­mes­tic cats in the rest of the world (ex­clud­ing China). Another source with figures for the num­ber of pets in more coun­tries is Bat­son (2008). How­ever, the es­ti­mates in these sources are now more than a decade old.

Note that dogs, cats, and other car­nivorous pets eat meat, which in­creases the num­ber of an­i­mals who are farmed for food. Thomp­son (2008) claims that pet food in­gre­di­ents in­clude meat and meat byprod­ucts. Note that even when byprod­ucts are used, it still sup­ports the meat in­dus­try as it al­lows them to get ex­tra rev­enue.

In Šimčikas (2019c), I es­ti­mated that there are 4.2M–7.8M pet snakes in the world. Since snakes are rep­tiles, their num­bers are in­cluded in the rep­tile num­bers in the table above. Some claim that pet snakes and other pet rep­tiles face sig­nifi­cant welfare is­sues (see How­ell and Ben­nett (2017), Pas­mans et al. (2017), War­wick et al. (2018) and Hu­mane So­ciety fact­sheet).

One group of pets that is not ex­plic­itly men­tioned in the table above is ex­otic an­i­mals. Millions of ex­otic an­i­mals are ei­ther taken from the wild or cap­tive-bred and then sold as ex­otic pets. There seems to be sub­stan­tial suffer­ing in­volved in the trans­port of these an­i­mals. Fur­ther­more, many of them are un­suit­able to be pets. Hence, they lead short and stress­ful lives in cap­tivity. (Nowak (2016), Act­man (2019)).

Or­na­men­tal fish (fish in aquar­iums)

I sus­pect that there is more un­cer­tainty about the num­ber of pet fish than the num­ber of other pets. Ac­cord­ing to Euromon­i­tor, there are only 1.15M pet fish in the UK. In con­trast, OATA (2019) claims that over 100M fish are kept in aquar­iums and ponds in the UK. How­ever, the claim by OATA (2019) is un­sub­stan­ti­ated. On the other hand, Euromon­i­tor es­ti­mates that there are 198M pet fish in China (172M in 2014), but pet­faira­sia.com claims that it was only 80M in 2014.

Note that in ad­di­tion to pet fish, there are also other or­na­men­tal fish used in pub­lic aquar­iums and el­se­where. How­ever, their num­bers seem to be much lower. Raja et al. (2019) claims that 99% of the global or­na­men­tal fish mar­ket is con­fined to hob­by­ists, and less than 1% is used for pub­lic aquar­iums and re­search. Similarly, Smith et al. (2012) claims that out of 1.1B or­na­men­tal fish im­ported to the U.S. be­tween 2000 and 2006, 99% were in­tended for com­mer­cial sale in the pet in­dus­try. Nei­ther of these ar­ti­cles backs up their claims with sources.

The num­ber of or­na­men­tal fish bred per year seems to be even higher than the num­ber of pet fish al­ive in house­holds:

  • Ac­cord­ing to table 5 in the 2013 Cen­sus of Aqua­cul­ture, more than 232M or­na­men­tal fish pro­duced in the U.S. were sold in 2013.

  • Satam et al. (2018) claims that more than 2B live or­na­men­tal fish are traded, pre­sum­ably per year (no source is pro­vided).

  • Cheong (1996) claims that an es­ti­mated 1B or­na­men­tal fish are traded an­nu­ally (no source is pro­vided). It also claims that the bulk of or­na­men­tal fish are farm-bred, but some are wild-caught.

Note that the num­ber of fish traded doesn’t in­clude fish that are sold as pets do­mes­ti­cally.

Stevens et al. (2017) claims that trans­porta­tion and han­dling of or­na­men­tal fish im­poses a range of stres­sors that re­sult in mor­tal­ity at rates that range be­tween 2% and 73%. As I un­der­stand it, this is the mor­tal­ity of fish be­fore they are sold. The ar­ti­cle re­views var­i­ous or­na­men­tal fish welfare prob­lems and con­cludes that it is a ma­jor con­cern.

Clos­ing thoughts

China

There were three large groups of farmed an­i­mals I per­son­ally didn’t know about be­fore writ­ing this ar­ti­cle: quail, frogs, and tur­tles. All three of these groups of an­i­mals seem to be pri­mar­ily farmed in China. Hence, es­tab­lish­ing an­i­mal ad­vo­cacy in China could be even more im­por­tant than I pre­vi­ously thought. As for the num­bers of these an­i­mals, it could be that some­one who can read Chi­nese could quickly find more ac­cu­rate es­ti­mates.

Num­bers is not all that matters

While in this ar­ti­cle I fo­cused on num­bers and I think that they are very im­por­tant, I don’t mean to im­ply that num­bers are all that mat­ters when choos­ing which group of an­i­mals to try to help. For ex­am­ple, if the goal is to re­duce suffer­ing, other fac­tors that may mat­ter in­clude:

  • Tractabil­ity (how difficult it is to make progress on the is­sue)

  • The in­ten­sity of suffer­ing of in­volved animals

  • The prob­a­bil­ity/​level of con­scious­ness of in­volved animals

  • The speed of the sub­jec­tive ex­pe­rience of in­volved an­i­mals (see To­masik (2016))

  • How much does tack­ling the is­sue con­tribute to the moral cir­cle ex­pan­sion, the growth of the an­i­mal ad­vo­cacy move­ment, etc.

  • The effect that tack­ling the is­sue will have on hu­mans and the environment

  • Per­sonal/​or­ga­ni­za­tional fit of the per­son or or­ga­ni­za­tion that is tak­ing action

For ex­am­ple, the num­ber of fish that are cooked and then eaten while they are still par­tially al­ive is prob­a­bly not very big. How­ever, cam­paign­ing against the prac­tice could in­voke a pub­lic out­rage, get more peo­ple in­volved in the an­i­mal welfare move­ment, and be a step to­wards mak­ing com­pas­sion for fish more main­stream. It could be a good first is­sue to tackle in coun­tries that don’t yet have an es­tab­lished an­i­mal ad­vo­cacy move­ment (e.g., China). The gained mo­men­tum could even­tu­ally be used to help other groups of an­i­mals. Note that I am very un­cer­tain about this par­tic­u­lar sug­ges­tion, I’m just us­ing it as an ex­am­ple of why we might not always choose to tackle the is­sues con­cern­ing the biggest groups of an­i­mals.

This ar­ti­cle doesn’t show the full picture

One of the goals of this ar­ti­cle was to provide a list of op­tions for what kind of prob­lems an­i­mal ad­vo­cates could tackle. How­ever, the list is in­com­plete be­cause it doesn’t cover is­sues re­lated to in­ver­te­brate and wild an­i­mal welfare. It could be that tack­ling these is­sues is even more im­por­tant than helping ver­te­brates in cap­tivity.

I prob­a­bly also missed some other groups of ver­te­brates kept in cap­tivity. If you know of any such groups of a sub­stan­tial size, or if you know of bet­ter sources about the num­ber of in­di­vi­d­u­als in any of the groups, please leave a com­ment.

Ap­pendix 1: Com­pre­hend­ing the num­bers (sec­onds of silence)

It can be difficult to com­pre­hend and com­pare es­ti­mates of an­i­mals listed in this ar­ti­cle be­cause we are not used to think­ing about such huge num­bers. One way to get a bet­ter in­tu­itive un­der­stand­ing of the num­bers is to con­vert them into units of time. This can help be­cause we are more used to think­ing about units of time of very differ­ent mag­ni­tudes (e.g., one sec­ond ver­sus one year).

The table be­low pre­sents the same num­bers as the ones in the sum­mary ta­bles at the be­gin­ning of the ar­ti­cle, ex­cept that all num­bers are con­verted into units of time. In­stead of show­ing how many an­i­mals hu­mans slaugh­ter, breed, or use per year, the fourth column shows how much time it would take to com­mem­o­rate ev­ery 10,000 an­i­mals hu­mans slaugh­ter, breed, or use per year with one sec­ond of silence. In­stead of the num­ber of an­i­mals al­ive at any time, the sec­ond column shows how much time it would take to com­mem­o­rate ev­ery 10,000 an­i­mals kept in cap­tivity with one sec­ond of silence. The table can also be ex­plored in this spread­sheet.

table

Ap­pendix 2: Differ­ent pre­sen­ta­tion of the an­i­mal numbers

In the table be­low, I pre­sent the same num­bers as in the sum­mary ta­bles at the be­gin­ning of the ar­ti­cle, but not grouped by species cat­e­gory, as this may be eas­ier to nav­i­gate for some peo­ple. This table can also be ex­plored in this spread­sheet.

Animal numbers table

References

ACTAsia for An­i­mals (2017). Re­port of dog and cat fur trade in China

Ae­bischer, N. J. (2019). Fifty-year trends in UK hunt­ing bags of birds and mam­mals, and cal­ibrated es­ti­ma­tion of na­tional bag size, us­ing GWCT’s Na­tional Game­bag Cen­sus. Euro­pean Jour­nal of Wildlife Re­search, 65(4), 64.

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Wald­horn, D. (2020). Coron­avirus and non-hu­mans: How is the pan­demic af­fect­ing an­i­mals used for hu­man con­sump­tion?

Warfield, K. (2018). Ware­house Packed With Frogs Has The Sad­dest Backstory

War­wick, C., Arena, P., & Steed­man, C. (2019). Spa­tial con­sid­er­a­tions for cap­tive snakes. Jour­nal of vet­eri­nary be­hav­ior, 30, 37-48.

WATTAgNet. (2018). FFAR offers $6 mil­lion for in-ovo sex­ing solution

Willett, M. (2013). China’s ‘Snake Village’ Breeds More Than 3 Million Snakes A Year. Busi­ness In­sider.

Willsher, K. (2012). Foie gras: French farm­ers defend ‘tra­di­tion’ af­ter ban in Cal­ifor­nia.

Woemp­ner, A. (2012). From PETCO to PETA: A Former PETCO Em­ployee Speaks Out

World An­i­mal Pro­tec­tion. (2014). The show can’t go on. End­ing wild an­i­mal abuse for entertainment

World An­i­mal Pro­tec­tion. (2019). Trad­ing cru­elty—how cap­tive big cat farm­ing fuels the tra­di­tional Asian medicine in­dus­try.

Xu, W., Chang, H., Wang, H. Y., Chang, G. B., Du, L., Lu, S. X., … & Wang, Q. H. (2003). Cross fer­til­ity be­tween the wild Ja­panese quail in the Weishan lake area and Do­mes­tic quail. Asian-aus­tralasian jour­nal of an­i­mal sci­ences, 16(10), 1421-1423.

Yee. A. (2016). Don­keys Are Fi­nally Get­ting More Respect

This es­say is a pro­ject of Re­think Pri­ori­ties. It was writ­ten by Saulius Šimčikas. Thanks to David Moss, Mar­cus A. Davis, and Kieran Greig for re­view­ing drafts of this post and mak­ing valuable com­ments. Spe­cial thanks to Sab­rina Ahmed who con­tributed to parts of the text.

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Notes


  1. Ar­gentina, Aus­tralia, Aus­tria, Belgium, Brazil, Bul­garia, Canada, Chile, China, Colom­bia, Czech Repub­lic, Den­mark, Egypt, Fin­land, France, Ger­many, Greece, Hong Kong, Hun­gary, In­dia, In­done­sia, Ire­land, Is­rael, Italy, Ja­pan, Malaysia, Mex­ico, Morocco, Nether­lands, New Zealand, Nor­way, Peru, Philip­pines, Poland, Por­tu­gal, Ro­ma­nia, Rus­sia, Saudi Ara­bia, Sin­ga­pore, Slo­vakia, South Africa, South Korea, Spain, Swe­den, Switzer­land, Taiwan, Thailand, Turkey, USA, Ukraine, United Arab Emirates, United King­dom, Viet­nam. ↩︎

  2. Un­for­tu­nately, the statis­tics don’t spec­ify which species of frogs are pri­mar­ily farmed in China. Coun­tries for which species is speci­fied seem to mostly farm Amer­i­can bul­lfrogs, ex­cept Thailand, which grows east Asian bul­lfrogs. Gratwicke et al. (2010), Mor­eira, Hen­riques, and Fer­reira (2013) and Warfield (2018) claims that frog farms mainly fo­cus on Amer­i­can bul­lfrogs, but I’m un­sure what this claim is based on. FAO claims that frog aqua­cul­ture pro­duc­tion that is not iden­ti­fied by species un­doubt­edly con­tains the pro­duc­tion of Amer­i­can bul­lfrogs, but the pro­por­tion is un­known. Mart­insen (2010) in­di­cates that there is some pig frog farm­ing in China. Ac­cord­ing to Altherr, Goyenechea, and Schu­bert (2011), “ap­prox­i­mately a dozen frog farms are pro­duc­ing Amer­i­can bul­lfrogs and other frog species.” ↩︎

  3. This is based on the fol­low­ing claims:

    • FAO page on Amer­i­can bul­lfrog farm­ing claims that fit­ter in­di­vi­d­u­als can reach mar­ket size (>180 g), in 3 months af­ter meta­mor­pho­sis.

    • Ayres et al. (2015) con­sid­ers Amer­i­can bul­lfrog slaugh­ter weights be­tween <100g and >251g and recom­mends slaugh­ter­ing at the weight of 201g.

    • Lutz and Avery (1999): “If the pri­mary mar­ket product will be frog legs, har­vest can be­gin when in­di­vi­d­ual frogs reach ap­prox­i­mately 175 grams (6 ounces), which should be in about 6 months. If skins are also to be used for leather, frogs can be grown to 250 grams (9 ounces) or even larger.”

    • Table 1 in Mor­eira, Hen­riques, and Fer­reira (2013) claims that slaugh­ter weight per frog in an ob­served pond was 300g.

    ↩︎
  4. Lower bound: 100,379 tonnes /​ 350 g = 287M. Up­per bound: 100,379 tonnes /​ 100 g = 1B ↩︎

  5. It seems that the Gratwicke et al. (2010) es­ti­mate is based on the fact that “a kilo­gram of ex­port-qual­ity frog legs re­quires 10 to 40 in­di­vi­d­ual an­i­mals” and that ac­cord­ing to FAO fish­eries data, in 2006 world pro­duced 75,000 tons of farmed frogs and 8,000 tons of wild-caught frogs (about 80M kg in to­tal). Based on this, it seems that the pa­per es­ti­mates that 0.8B (80M ✕ 10) to 3.2B (80M ✕ 40) frogs are con­sumed each year. How­ever, in FAO’s FishS­tatJ, I see that 75,000 and 8,000 figures are for live weight in tonnes, not frog-leg weight. It also seems that the pa­per con­fuses tonnes with tons but that only has a slight im­pact on the es­ti­mate. ↩︎

  6. Ac­cord­ing to FAO, “pre­co­cious tad­poles be­come froglets in 45 days, while most of the pop­u­la­tion achieves this in 90-120 days, and a small por­tion of the co­hort (7-12 per­cent) will meta­mor­phose af­ter one year or more, even in trop­i­cal con­di­tions.” For the pur­pose of the es­ti­ma­tion, I’ll as­sume that the av­er­age is in the range of 60-150 days (or 2 to 5 months). FAO also claims that “un­der trop­i­cal con­di­tions, in 3 months af­ter meta­mor­pho­sis, and sex­ual ma­tu­rity in as early as 7 months af­ter hatch­ing, while weak­est may take over one year.” Ac­cord­ing to table 1 in Lutz and Avery (1999), bul­lfrogs typ­i­cally reach the weight of 175g in 8 months af­ter meta­mor­pho­sis. Later, the ar­ti­cle seem­ingly con­tra­dicts it­self by claiming that they reach the weight of 175g in about 6 months. Based on this, it seems that Amer­i­can bul­lfrogs are slaugh­tered 4 months to 8 months af­ter meta­mor­pho­sis on av­er­age. Hence, the slaugh­ter age of Amer­i­can bul­lfrogs from hatch­ing to slaugh­ter seems to be be­tween 6 months (2+4) and 13 months (5+8). Mor­eira, Hen­riques, and Fer­reira (2013) claims that the pro­duc­tion has 1.5 cy­cles per year (egg phase up to slaugh­ter weight). If I un­der­stand it cor­rectly, that means that frogs live up to 12 /​ 1.5 = 8 months, which is within my es­ti­mated range. This video about “asian” frogs claims that “[i]t may take a year, or longer, for tad­poles to trans­form into young frogs. Grow­ing a frog to a mar­ketable size fre­quently takes an­other two years, or three years to­tal from eggs to har­vest.” Mart­insen (2010) claim that farmed pig frogs reach ma­tu­rity in just three months. This sug­gests that other farmed frog species may have sig­nifi­cantly differ­ent lifes­pans. Due to this, I sub­jec­tively change the range from 6-13 months to 4-20 months. ↩︎

  7. Lower bound: 290M ✕ 4 months /​ 12 months = 96.7M. Up­per bound: 1B ✕ 20 months /​ 12 months = 1.67B ↩︎

  8. Note that FAO may not be re­port­ing num­bers for all coun­tries. For ex­am­ple, ac­cord­ing to table 8 in the 2013 U.S. aqua­cul­ture cen­sus, 3.6M farmed tur­tles were sold “whole” in the U.S. in 2013, but they are not in­cluded in FishS­tatJ. I’m also un­sure why the table 7 in FAO’s The State of World Fish­eries and Aqua­cul­ture 2018 re­port has slightly higher num­bers of Chi­nese soft­shell tur­tle pro­duc­tion than FAO’s FishS­tatj. The differ­ence for 2016 is 4%. ↩︎

  9. Ac­cord­ing to a Fish­count es­ti­mate, China pro­duced 22B-68B fish in 2010. China’s aqua­cul­ture pro­duc­tion in weight in­creased sub­stan­tially be­tween the early 2000s and 2010, so the num­ber of fish pro­duced in the early 2000s was prob­a­bly lower. Hence, 600B-700B fry pro­duced by China in the early 2000s would im­ply more than a 90% mor­tal­ity rate, which I’d find sur­pris­ing. How­ever, it could be that some of the fry were used for fish stock­ing or some other pur­poses. Fi­nally, it’s pos­si­ble that these num­bers re­fer to the num­ber of fish eggs pro­duced and that many of these eggs don’t hatch or that many fish die in hatcheries soon af­ter hatch­ing. ↩︎

  10. This is es­ti­mated as fol­lows. Lower bound: 35B ✕ 8 days /​ 365.25 days = 0.8B. Up­per bound: 150B ✕ 3 months /​ 12 months = 50B ↩︎

  11. See “Species for as­phyx­i­a­tion es­ti­mate” tab in this spread­sheet. Note that I summed up var­i­ous species of her­ring, cod, whit­ing, sole, dab, and plaice, even though the time it takes for these species to suffo­cate is prob­a­bly differ­ent. ↩︎

  12. Lower bound es­ti­ma­tion: 30B ✕ 25 min­utes ✕ 50% /​ 525600 min­utes = 0.71M. Up­per bound es­ti­ma­tion: 102B ✕ 250 min­utes ✕ 100% /​ 525600 min­utes = 48.5M. 525600 min­utes is the num­ber of min­utes there are in a year. ↩︎

  13. Romeo (2019) claims that Ars Ital­ica’s farm houses 300,000 stur­geons and that Ars Ital­ica and Calvi­sius Caviar to­gether stretch over 250 acres and pro­duce 28 tons (which is 25.4 tonnes) of caviar per year. Ac­cord­ing to a video from Calvi­sius Caviar web­site, their farm stretches 150 acres. If we as­sume that the farm area is roughly pro­por­tional to the num­ber of fish in the farm, we get that Ars Ital­ica pro­duces around 25.4 ✕ (250 − 150) /​ 250 = 10.16 tonnes of caviar. Bronzi et al. (2019) claims that the world’s caviar pro­duc­tion is 364 tonnes. Us­ing this in­for­ma­tion, we can ex­trap­o­late that there are 300,000 ✕ 364 /​ 10.16 = 10.75M stur­geons in caviar farms in the world. This ex­trap­o­la­tion is very un­cer­tain for mul­ti­ple rea­sons. The biggest one is that there are many differ­ent stur­geon species be­ing farmed.

    Note that Romeo (2019) claims that 25 tonnes of caviar pro­duced by the two farms in Italy amounts to 15% of the world’s caviar. How­ever, Bronzi et al. (2019) claims that the world’s caviar pro­duc­tion is 364 tonnes, which sug­gests that the two farms pro­duce 25 tonnes /​ 364 tonnes = 7% of the world’s caviar. I’m un­sure why there is this in­con­sis­tency, but for this es­ti­ma­tion, I used the Bronzi et al. (2019) figure be­cause it pro­vided much more de­tail about the figure. ↩︎

  14. Ac­cord­ing to the table 30 in the Cen­sus of Agri­cul­ture, in 2017 in the U.S., there were 368.2M lay­ers, 130.5M pul­lets, and 7M roost­ers. So the to­tal num­ber of chick­ens in­volved in egg pro­duc­tion in the U.S. is about 368.2M+130.5M+7M=505.7M, which is 37% higher than the num­ber of hens. If we in­crease the 7.5B figure for the num­ber of hens in the world by 37%, we get 10.3B. 10.3B is likely an over­es­ti­mate of the num­ber of chick­ens in­volved in egg pro­duc­tion be­cause we already know that the UK in­cluded roost­ers and pul­lets in the hen num­bers. Similarly, the 7.8B is likely an un­der­es­ti­mate be­cause the U.S. did not. ↩︎

  15. Ex­trap­o­la­tions as­sumed that the ra­tio be­tween chicken slaugh­ters and broiler breed­ers al­ive at any time is similar in differ­ent coun­tries and years. If broiler moth­ers in differ­ent coun­tries lay a similar num­ber of eggs per month, these es­ti­ma­tions should be roughly cor­rect. They might still be a bit in­ac­cu­rate be­cause:

    • I don’t take broiler mor­tal­ity rates into account

    • As ex­plained in the ap­pendix of Šimčikas (2019a), not all chicken slaugh­ters that are in­cluded in the statis­tics are broilers. E.g., U.S. statis­tics in­clude “spent” hens who are slaugh­tered when their egg pro­duc­tion slows down. For some coun­tries, chicken slaugh­ter to­tals also in­clude other slaugh­ters of other species of birds.

    ↩︎
  16. Ac­cord­ing to USDA’s Chick­ens and Eggs 2017 Sum­mary, there were about 56.5M broiler moth­ers and 3.3M egg-lay­ing hen moth­ers in the U.S. in 2017. That means that meat chicken moth­ers make up around 94.5% of all chicken moth­ers in the U.S. Ac­cord­ing to Table 30 in the 2018 Cen­sus of Agri­cul­ture, in 2017, there were 7M roost­ers in the U.S. My guess is that about 7M ✕ 94.5% = 6.6M of them are used for meat chicken pro­duc­tion. It fol­lows that in the U.S., for ev­ery meat chicken father, there are 56.5M/​6.6M = 8.56 moth­ers. If we as­sume that this ra­tio holds in other coun­tries, we can then es­ti­mate that there are be­tween 40M (350M /​ 8.56) and 70M (600M /​ 8.56) meat chicken fathers in the world. ↩︎

  17. E.g., Min­vielle (2004) num­bers for China seem to be based on a source that is from 1991. Many other num­bers are taken from Min­vielle (1998) which cites other sources that were pub­lished be­tween 1991 and 1997. Min­vielle (2004) also seems to be the ul­ti­mate source for Lukanov (2019) claim that “over nine billion quail are pro­duced each year in East Asia”, which means that the claim is also out­dated. Fur­ther­more, Min­vielle claims that there are over nine billion quail eggs pro­duced, not nine billion quail, as Lukanov (2019) claims. ↩︎

  18. Es­ti­mate of the num­ber of quail al­ive at any time in coun­tries other than China: 36M (Brazil) + 7.4M (U.S.) + 6M (Spain) + 3.6M (France) + 2.3M (Italy) = 55.3M. Es­ti­mate of the num­ber of quail slaugh­tered in these coun­tries: 43M (Brazil) + 23M (U.S.) + 66M (Spain) + 38M (France) + 24M (Italy) = 194M. The 43M figure for Brazil is an ed­u­cated guess. It seems that most quail in the coun­try are raised for eggs. da Cunha (2009) claims that in China, quail have a 10-month pro­duc­tive pe­riod. 36M × 12 months /​ 10 months = 43M. ↩︎

  19. I found the fol­low­ing sources that could be use­ful if some­one wanted to try to es­ti­mate the num­ber of birds in­volved in down and feather pro­duc­tion:

    • Sch­mitz (2016) claims that about 186M kg of down and feathers are traded annually

    • Buck­land and Guy (2002) claims that 80g-120g of down and feathers are ob­tained per geese plucking

    • Kozák (2011) goes into more de­tail about how much down and feathers can be ob­tained from geese and other birds

    How­ever, I don’t know. the fol­low­ing:

    • How much down and feathers are con­sumed do­mes­ti­cally (and hence not traded)

    • What pro­por­tion of down comes from geese and what from ducks or other birds,

    • How preva­lent is live-pluck­ing, and how many times are birds live-plucked be­fore slaugh­ter on av­er­age.

    Also, I don’t feel like I have a good enough un­der­stand­ing of the down and feather pro­duc­tion to pro­duce an es­ti­mate. ↩︎

  20. Swift­let farm­ing is con­ducted in man-made build­ings that imi­tate cave-like en­vi­ron­ments in or­der to provide al­ter­na­tive nest­ing sites and at­tract swiftlets. The farm­ers do not con­trol the birds’ move­ment, breed­ing or their diets. The swiftlets tend to live with­out in­terfer­ence and ap­pear to re­cover well once their nests are re­moved, as long as this does not oc­cur be­fore their young reach a cer­tain age. ↩︎

  21. I think that FAO statis­tics in­clude at least some work­ing an­i­mals be­cause there are coun­tries like Afghanistan, Chad, and Ethiopia that have mil­lions of asses al­ive, but no asses slaugh­tered for meat. When googling, I see ev­i­dence that ar­ti­cles like this and this about asses be­ing used as work an­i­mals in these coun­tries. Fi­nally, ar­ti­cles like Church (2014) and Brooke (2015) that cite FAO statis­tics and claim that nearly all horses, mules and asses in­cluded in FAO statis­tics are work an­i­mals. ↩︎

  22. Here are some of the es­ti­mates of the num­ber of work­ing an­i­mals in the world:

    • Chirg­win (1996): “Con­sid­er­ing all the differ­ent types of farm an­i­mals, the num­ber used wor­ld­wide as work an­i­mals is es­ti­mated at no less than 250 mil­lion and may well be over 300 mil­lion.”

    • Wil­son (2003): “In­for­ma­tion on draught an­i­mal num­bers is scarce al­though es­ti­mates of 300 mil­lion an­i­mals are some­times used”

    • Ac­cord­ing to Wil­son (2003), Pear­son (1999) claims that “51% of the 921 mil­lion cat­tle in the de­vel­op­ing world in 1994 were used for work as were 35% of 135 mil­lion buf­falo, 65% of 43 mil­lion horses, 87% of 43 mil­lion don­keys, 70% of 14 mil­lion mules and 15% of 19 mil­lion camels “. In to­tal, that would be nearly 600 mil­lion mam­mals.

    • Wor­l­dan­i­mal.net claims that “the an­i­mal work force is es­ti­mated at about 300 mil­lion an­i­mals and the num­bers are ris­ing.” It seems that this ar­ti­cle uses a broader defi­ni­tion of work­ing an­i­mals,to in­clude the ones used in ther­apy, herd­ing, hunt­ing, etc. How­ever, this may have a limited im­pact on the es­ti­mate be­cause it claims that “the ma­jor­ity of work­ing an­i­mals are in­volved in trans­port and agri­cul­ture.”

    • The In­ter­na­tional Coal­i­tion for Work­ing Equids claims that “an es­ti­mated 200 mil­lion work­ing an­i­mals are es­sen­tial to the liveli­hoods of some of the poor­est com­mu­ni­ties wor­ld­wide.”

    Note that none of the sources I’ve seen ex­plained how they ar­rived at the cited es­ti­mates. ↩︎

  23. The name of the item is “Ro­dents, other”. I’m un­sure why there is “other” in the de­scrip­tion since there are no other ro­dents on the list. Per­haps it’s be­cause rab­bits and hares are some­times mis­tak­enly clas­sified as ro­dents. ↩︎

  24. USDA (2000) also con­tains the fol­low­ing sen­tences: “One com­mer­cial breeder claims that five per­cent of the to­tal num­ber of rats and mice bred in the United States-some 200-400 mil­lion in all—are bred for re­search. Re­searchers are rea­son­ably cer­tain that they have iden­ti­fied those pro­duc­ers. How­ever, the in­di­vi­d­u­als and/​or small com­pa­nies that pro­duce rats and mice for other pur­poses—an es­ti­mated 190 to 380 mil­lion an­i­mals—have not been clearly iden­ti­fied through the re­search.” I’m un­sure what are those other pur­poses. One of them is al­most cer­tainly feed­ing pet snakes and other car­nivorous an­i­mals kept in cap­tivity. ↩︎

    • The League Against Cruel Sports claims that around 35M pheas­ants and par­tridge are re­leased on the UK shoot­ing es­tates each year

    • Humphries (2019) claims that there are 30M pheas­ants and 6M par­tridge reared on Bri­tish game farms.

    • Game and Wildlife con­ser­va­tion trust claims that an es­ti­mated 35M pheas­ants are re­leased each year.

    ↩︎
  25. Ar­gentina, Aus­tralia, Aus­tria, Belgium, Brazil, Bul­garia, Canada, Chile, China, Colom­bia, Czech Repub­lic, Den­mark, Egypt, Fin­land, France, Ger­many, Greece, Hong Kong, Hun­gary, In­dia, In­done­sia, Ire­land, Is­rael, Italy, Ja­pan, Malaysia, Mex­ico, Morocco, Nether­lands, New Zealand, Nor­way, Peru, Philip­pines, Poland, Por­tu­gal, Ro­ma­nia, Rus­sia, Saudi Ara­bia, Sin­ga­pore, Slo­vakia, South Africa, South Korea, Spain, Swe­den, Switzer­land, Taiwan, Thailand, Turkey, USA, Ukraine, United Arab Emirates, United King­dom, Viet­nam. ↩︎

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