Animal welfare dangers of worldwide aquaculture


The unprecedented progress of aquaculture includes well-documented environmental and public-health prices, however much less is known about world animal welfare dangers. Integrating knowledge from a number of sources, we estimated the taxonomic variety of farmed aquatic animals, the variety of people killed yearly, and the species-specific welfare data (absence of which signifies excessive threat). In 2018, FAO reported 82.12 million metric tons of farmed aquatic animals from six phyla and a minimum of 408 species—20 occasions the variety of species of farmed terrestrial animals. The farmed aquatic animal tonnage represents 250 to 408 billion people, of which 59 to 129 billion are vertebrates (e.g., carps, salmonids). Specialized welfare info was accessible for 84 species, solely 30% of people; the remaining 70% both had no welfare publications or had been of an unknown species. With aquaculture progress outpacing welfare data, instant efforts are wanted to safeguard the welfare of high-production, understudied species and to create insurance policies that decrease welfare dangers.


Aquaculture, the farming of aquatic vegetation (e.g., seaweeds) and animals (e.g., carps and shrimps), is a fast-growing business (1) and touted as a essential sector for a sustainable future (2). With seize fisheries in decline worldwide (3), some additionally promote aquaculture as an answer to world meals insecurity (4). Enthusiasm for aquaculture, nonetheless, is tempered by proof that aquatic animal farming has not relieved fishing stress on wild animal populations (5) and, as an enterprise that has solely not too long ago reached a world scale, includes many unchecked dangers. To date, biodiversity loss, ecological injury, air pollution, antibiotic overuse, lack of sustainability, and human rights abuses have all been recognized and investigated as main areas of concern (610). Animal welfare points in aquaculture are additionally attracting elevated consideration (1117), with ongoing estimates suggesting that the variety of particular person animals killed annually is probably going better than the roughly 70 billion people concerned in terrestrial animal agriculture (1, 18). Here, we assess for the primary time the general world scope and nature of the aquaculture welfare threat—the vary of species used, the full variety of people concerned, and the state of the data relating to their welfare.

Animal welfare—how effectively an animal is biologically, behaviorally, and emotionally dealing with their surroundings (19, 20)—has turn out to be a precedence in nations all over the world (21, 22). The ethical crucial to think about the experiences of different species is a rising coverage agenda worldwide, with nationwide, state, and native legislatures often passing stricter animal welfare protections (23). Animal welfare can be more and more acknowledged as integral to sustainability, helpful to the United Nations Sustainable Development Goals for 2030, and a excessive precedence for customers all over the world (24, 25). Food merchandise with animal welfare labeling carry a premium in markets from the European Union to Asia to the Americas (2628). Moreover, a number of fields are establishing the interdependencies between animal welfare and environmental and human well being, e.g., agriculture (29), anthropology (30), conservation biology (31), environmental science (32), human medication (33) psychology (34), and veterinary science (35). These numerous disciplines and world forces underpin the pressing want to grasp, shield, and enhance the welfare of all animals; nonetheless, consideration of the welfare of aquatic animals in farmed methods has been absent from the dialogue till very not too long ago (11, 36, 37).

Ongoing efforts to appropriate this oversight have been motivated partly by the rising physique of proof that many aquatic species reside much more advanced social and emotional lives than beforehand understood (3840). For instance, a 2014 evaluate of the scientific literature on ache discovered that fish and decapods (e.g., shrimp) show hallmarks of the flexibility to expertise ache (41). Similarly, work in numerous species of fish has revealed advanced cognitive skills (42), together with device use (43), particular person personalities (44), and robust preferences concerning the environments through which they reside (4547). Recent work with aquatic invertebrates can be uncovering sudden skills. In addition to the outstanding and numerous psychological capabilities of cephalopods (48, 49), research have discovered advanced maze studying in shore crabs (50), refined navigation in spiny lobsters (51), and emotional conduct in crayfish (52). While there isn’t any singular, agreed upon cutoff for when welfare protections are ethically essential, lots of the species concerned in aquaculture—together with finfish and tetrapods, decapod crustaceans, and cephalopods—are actually acknowledged as having the behavioral, cognitive, and affective skills that meet extensively accepted standards for ethical consideration and welfare safety (3840, 53).

Understanding and guaranteeing the welfare of aquatic animals is a essentially completely different endeavor than it’s for terrestrial animals, nonetheless. First, not like terrestrial animal agriculture, the overwhelming majority of species at the moment farmed in aquaculture are both wild or solely not too long ago domesticated (54, 55). Aquaculture originated hundreds of years in the past, however conventional practices had been restricted to a small variety of species, cultivated at a minor scale (56). It is just previously a number of many years that concern about world overfishing and scientific advances have propelled an explosion within the variety of farmed aquatic species (57). As a end result, a lot of the people in trendy aquaculture will not be biologically tailored to life in captivity, which poses severe welfare dangers, particularly within the absence of historic and conventional data about find out how to look after newly farmed species. The detrimental penalties of those compound threat elements are evident in a latest evaluation of 41 species in aquaculture, which decided that below present circumstances, welfare for many species is prone to be poor throughout the life cycle: from the excessive chance of malformations and physiological defects at start to restricted mobility, excessive aggression, and poor dealing with all through improvement to “extreme pain and suffering” throughout slaughter (11).

Second, whereas the scientific literature on terrestrial animal welfare has collected throughout many many years and has solely wanted to cowl roughly 20 species, the literature on the welfare of animals in aquaculture is new and must cowl an order of magnitude extra species [at least 300 (57)]. Species-specific welfare analysis is important to grasp a person’s welfare as a result of even inside the similar genus, completely different species can show extensively divergent organic and behavioral responses, with completely different implications for his or her welfare (58). Without species-specific knowledge, welfare requirements, evaluation instruments, labeling schemes, legislative initiatives, and enforcement won’t be supported by dependable data, which leads welfare protections to be weak, ineffective, or nonexistent (59, 60). Thus, whereas the presence of species-specific welfare publications doesn’t guarantee an animal’s welfare, its absence does sign excessive welfare dangers.

To consider the extent and magnitude of the welfare-knowledge hole, we aimed to (i) quantify the taxonomic variety of the animals at the moment concerned aquaculture, (ii) present formal estimates of the variety of people killed for consumption in 2018, and (iii) gauge the extent to which the scientific literature is assembly the various wants of the animals in aquaculture. Data from the Food and Agriculture Organization (FAO) of the United Nations (FishStatJ) offered estimates of the quantity and variety of aquatic animals utilized in farming worldwide within the 12 months 2018. Reflecting the extent of their commodification, animals in aquaculture are reported in manufacturing weight, not as variety of people (as is the norm for terrestrial animal agriculture). To generate estimates of the variety of particular person aquatic animals utilized in 2018, subsequently, we matched the FAO tonnage knowledge to biometric info in FishBase [; (61)] and slaughter weights from fishcount (; (18)]. Last, we collected bibliometric knowledge from Web of Science (WOS; Clarivate Analytics) to evaluate the scientific info accessible on every species. These strategies mix to offer a conservative estimate of the welfare dangers concerned in world aquaculture.


FAO reported {that a} complete of 82.12 million metric tons of animals had been produced in aquaculture in 2018, comprising a minimum of 408 species distributed throughout six phyla, most of which had been from the Chordata phylum (68% of listings; Fig. 1A). The different phyla had been all invertebrates, with Mollusca (e.g., clams and mussels) and Arthropoda (e.g., shrimps and crabs) having the second and third most FAO listings, respectively. We estimate that the full tonnage corresponds to roughly 250 to 408 billion particular person animals: 191 to 279 billion invertebrates and 59 to 129 billion vertebrates (Fig. 1B).

Fig. 1 Diversity and scope of worldwide animal aquaculture manufacturing (knowledge FAO, 2018).

(A) At the worldwide degree, every FAO itemizing usually corresponds to the manufacturing of a selected species, however a list might also consult with the next taxonomic grouping similar to a genus, class, or phylum not listed elsewhere within the knowledge. The variety of FAO listings is subsequently a conservative estimate of the full variety of species concerned in aquaculture manufacturing. Bars characterize the full variety of FAO aquaculture animal listings by phylum and the dotted grey line refers back to the complete variety of FAO listings for all of terrestrial animal agriculture mixed. (B) Estimates of the variety of particular person animals in aquaculture manufacturing for 2018. The error bars characterize the current analyses’ higher and decrease estimates for the variety of people concerned in world animal aquaculture by phylum. The dotted grey line refers back to the complete quantity people concerned throughout all of terrestrial animal agriculture mixed.

Of the 408 listings, 231 species had no welfare publications, 59 had one to 4 welfare publications, 25 had 5 or extra welfare publications, and 93 of the itemizing didn’t comprise species-level taxonomic info (Table 1, as of May 2020). In accordance with our estimates utilizing probably the most particular taxonomic knowledge accessible, 128 to 183 billion people (48% of complete aquaculture) will not be lined by any welfare literature (105 to 136 billion invertebrates and 23 to 48 billion vertebrates), and a further 50 to 102 billion people (22% of complete aquaculture) are of unknown species and thus can not have any species-specific welfare publications (35 to 69 billion invertebrates and 15 to 33 billion vertebrates); 58 to 91 billion people (23% of complete aquaculture) are lined by one to 4 welfare publications (51 to 75 billion invertebrates and seven to 16 billion vertebrates), and 14 to 32 billion people (7% of complete aquaculture) had been lined by 5 or extra welfare publications (all vertebrates; Table 1).

Table 1 Welfare by phyla.

The variety of people and minimal variety of species concerned (FAO itemizing is an underestimate of species complete) by welfare analysis and phyla.

Further inspecting these knowledge by FAO itemizing exhibits the extent of the issue: Billions of particular person animals belonging to lots of of various species will not be lined by any animal welfare publications (Fig. 2). Information on the 5 vertebrates with highest variety of people by aquatic surroundings (freshwater versus marine) will be present in Table 2 (see the Supplementary Materials for info on all 2018 FAO listings; desk S1).

Fig. 2 Welfare data and variety of people per FAO itemizing (2018).

Each FAO itemizing usually refers back to the manufacturing tonnage of a selected species, through which case we searched the WOS for species-specific welfare publications and recorded whether or not there have been no publications (no welfare), one to 4 publications (little welfare), or 5 or extra publications (5+ welfare). We recorded FAO listings that referred to increased taxonomic grouping (similar to genus or class) as species unknown. The dots characterize the lower-bound estimate of variety of particular person animals concerned for that itemizing and are jittered vertically to reduce overlap. Dots measurement corresponds to aquaculture manufacturing tonnage.

Table 2 Top vertebrates in world aquaculture by variety of people and surroundings (freshwater versus marine).

Although there’s a modest physique of welfare literature for a few of these species (5 or extra welfare publications), a number of species have only a few or no publications about their welfare, or their species is unknown. In the FAO knowledge, nei stands for “not elsewhere included.” N/A, not relevant.


In 2018, 250 to 408 billion particular person animals from greater than 408 species had been farmed in aquaculture. Integrating these estimates with the scientific literature reveals the magnitude of the animal welfare threat. Only 25 species (similar to 14 to 32 billion people, 7% of complete aquaculture) are lined by even a modest physique of welfare literature (5 or extra publications). The remaining 383+ species (similar to 236 to 376 billion people, 93% of complete aquaculture) had few to no welfare publications. By quickly increasing the cultivation of a large variety of undomesticated species, aquaculture is now characterised by the intensive administration of billions of people within the absence of primary data about how to make sure their welfare.

It is mostly understood that animal welfare coverage should be grounded in scientific data; within the absence of such info, protections can be weak, misinformed, or missing. Thus, whereas species-specific science doesn’t assure particular person well-being (e.g., billions of chickens nonetheless face poor dwelling circumstances regardless of many years of analysis on their welfare), its absence does sign excessive threat. In aquaculture, that predicament is borne out by latest work systematically evaluating typical aquaculture circumstances. For a lot of the species thought of, present practices entail poor welfare throughout all phases of manufacturing (11).

Strategies to deal with this pressing welfare threat fall roughly into three, complimentary classes, solely certainly one of which includes conventional animal welfare science. While extra species-specific info is undoubtedly wanted, producing dependable and actionable data is extraordinarily useful resource intensive and sluggish to translate into coverage. In the close to time period, going from some data about a number of species to authoritative data about lots of of species is solely not possible. In the meantime, billions of particular person animals will proceed to face circumstances which are seemingly harming their welfare. Although worldwide help for fish welfare science has elevated over the previous few many years (62), these investments haven’t stored tempo with the enlargement of aquaculture (1, 63). Moreover, animal welfare is only one of a number of elements to think about together with environmental impacts, meals safety, and others (16, 17).

There is, however, a hidden benefit to those troubling circumstances. The enlargement of aquaculture is a latest sufficient phenomenon that scientific, civic, and monetary enter can nonetheless play a big position in shaping its future. For instance, many years of analysis has established that the cultivation of carnivorous species, e.g., Atlantic salmon (Salmo salar), pose better sustainability dangers, together with welfare, than herbivorous species, e.g., Nile tilapia (Oreochromis niloticus) (7, 64, 65). Going ahead, addressing these elements would require that better emphasis is positioned on cultivating species with fewer welfare and environmental dangers, e.g., seaweeds and a few bivalves (17), fairly than these with better dangers, e.g., cephalopods (16). This strategy to addressing the welfare dangers in aquaculture will be thought of a structural change or system change methodology, rising and growing the cultivation of the bottom threat species whereas constructing consensus round prohibitions towards additional efforts to domesticate and cultivate these of highest threat (16, 17, 66). Future analysis assessing the sustainability of aquaculture will profit from incorporating animal welfare parameters to realize a extra full image of the prices concerned within the ongoing makes an attempt to farm wild aquatic animals.

Work aimed toward tackling the aquaculture welfare analysis hole can search to establish, benchmark, standardize, and enhance upon welfare finest practices inside present aquaculture settings, together with leveraging historic data. For instance, promising latest research have investigated conventional practices of offering fish with a temperature gradient to permit for behavioral thermoregulation (67) and the consequences of accelerating structural complexity in trendy aquaculture settings (68). When working inside manufacturing methods, it’s particularly necessary to acknowledge that welfare will not be synonymous with manufacturing optimization (69, 70), a notion that a few of the present work on fish and aquatic invertebrate welfare overlooks. Many of the articles counted as welfare publications within the current evaluation utilized a production-oriented lens to welfare, e.g., “Effects of different stunning/slaughter methods on frozen fillets quality of cobia (Rachycentron canadum).” Healthy organic functioning is a vital element of welfare, and throughout aquaculture, illness is a major concern (71). On its personal, nonetheless, organic well being will not be enough to make sure welfare and may, at occasions, be too simply be conflated with financial and manufacturing optimization (72). Instead, a extra wholistic strategy to welfare, together with consideration to psychological well being and ecologically related behaviors, is required (20).

Last, an “animal-first” strategy to welfare analysis is required (73). Some welfare-relevant info can solely be garnered by finding out animals for their very own sake, outdoors the constraints of the present farming methods, and by adhering to ideas of avoiding hurt, offering advantages, and respecting a person animal’s company and autonomy (7476). This strategy to welfare analysis is an extension of latest discussions of “positive welfare” and the calls to offer animals with a “good life,” each of which acknowledge that minimizing struggling doesn’t guarantee an honest high quality of life and that mere survival will not be the identical as acceptable welfare (7780). One of some great benefits of the animal-first strategy is that it speaks to the considerations of a number of stakeholders concurrently. It can present distinctive “within-system” options and fill gaps relating to baseline behavioral expectations [e.g., current industry standards markedly increase aggression in coho salmon (45)]. By prioritizing the pursuits of the person, the animal-first strategy additionally supplies primary science knowledge and solutions foundational questions relating to the explanations for attending to a selected species’ welfare within the first place, e.g., their capacities, sapience, and sentience. Although comparatively new for analysis packages with farmed fishes and particularly aquatic invertebrates, indications of the utility of this strategy for aquatic animals exist already [e.g., (38, 81, 82)].

The trendy enlargement of aquaculture is outstanding for its measurement and scope and the untracked harms confronted by the billions of aquatic animals it produces annually. Addressing these welfare dangers in live performance with different dangers—e.g., environmental degradation, human rights abuses, meals safety, and fisheries depletion—would require a multipronged technique. First, threat will be mitigated structurally with funding, analysis, coverage, and advocacy to help the infrastructure to domesticate species with low welfare and environmental considerations (e.g., seaweeds) and disincentivize the cultivation of species with excessive welfare and environmental considerations (e.g., cephalopods). Second, to align aquaculture with present scientific data and civic expectations, analysis tackling species-specific welfare questions might want to handle all features of welfare (organic, psychological, and ecological). Last, to generate an entire image of those advanced, fascinating, and principally wild species, high-quality details about their lives outdoors the present methods of manufacturing can be wanted. Although aquaculture has been round for hundreds of years, its present enlargement will not be solely unprecedented, posing nice threats, but in addition has the chance to make scientifically grounded and wiser selections going ahead. This work contributes to the mounting proof of the urgency of that obligation.


Number of species and tonnage: FAO listings of aquaculture manufacturing

Using FishStatJ, the FAO’s dataset on world aquaculture manufacturing, we exported info on all of the aquatic animals farmed in all geographical areas for 2018 (probably the most not too long ago accessible 12 months as of May 2020). Each itemizing on this dataset corresponds to a species, a hybrid, or an aggregation of a number of species not elsewhere included within the dataset, e.g., “Snappers nei (not elsewhere included)” and tonnage for 2018. The FAO makes use of the Aquatic Sciences and Fisheries Information System (ASFIS) to code the widespread names of the aquatic animals. We used the ASFIS scientific title listings to match the widespread names of the aquatic animals listed within the FAO aquaculture manufacturing dataset with their scientific names (genus and species) and better taxonomic classifications (household, order, class, and phylum). Some listings point out that tonnage as “not available” or “known to be nil or zero.” The authentic knowledge contained 745 listings, however after eradicating these with no reported tonnage, 408 constructive tonnage listings remained at least estimate of the variety of species concerned in aquaculture in 2018.

Estimating the variety of people: Biometric knowledge (FishBase) and harvest weights (FishDepend)

FAO tracks aquaculture as manufacturing weights for every itemizing, not as people (as is finished in terrestrial animal agriculture). Calculating the variety of people farmed in aquaculture thus requires estimating, for every species, the everyday weight of a person at processing and utilizing that determine to back-calculate the variety of people farmed that 12 months. Using a wide range of sources, the web site FishDepend has recognized and compiled dependable higher and decrease harvest weights for 48 aquatic species (18). We used these knowledge (publicly accessible at together with a two-step course of to generate an upper-bound and a lower-bound estimate of seemingly harvest weights for every itemizing. With these harvest-weight estimates, we had been capable of generate believable vary of people farmed for every itemizing.

As step one, we estimated most progress capacities for every itemizing. Maximum progress weight of a species will be calculated utilizing the traditional equation: W = a*Lb, which describes the connection between a person’s weight (W) and size (L). The parameters a, b, and Lmax (most size) are fixed and effectively described for a lot of aquatic species (83). Of the 408 listings in 2018 with constructive tonnage knowledge, we had been capable of match 234 listings to all the mandatory biometric parameters a, b, and Lmax from FishBase (61). For the remaining 174 listings, we used the closest taxonomic median info to impute the seemingly most weight of a person of that group. In different phrases, if we didn’t have biometric info for a sure species itemizing, we sought the median info for different species in its genus. If we lacked the mandatory info for the genus, we used median info for different family members, then order, class, phylum. This process generated estimates for the utmost weight (Wmax) of every itemizing in our dataset.

Second, we decided the seemingly harvest weight for every species. In farming, people are usually taken for slaughter at a measurement effectively beneath their progress most. Merging the FishBase most weight knowledge with the FishDepend harvest weight knowledge revealed a robust relationship: Larger species are harvested at a tinier fraction of their most capability than smaller bodied species (r > 0.79, P < 0.0001; Fig. 3; see Table 3 for mannequin info). For instance, rainbow trout (Oncorhynchus mykiss) can attain weights of greater than 18 kg (40 lb) however are marketed at weights of as much as 5 kg (11 lb) or about 27% of capability. Mozambique tilapia (Oreochromis mossambicus), then again, attain a most weight of round 1 kg (2.2 lb) however are marketed at weights as much as 0.eight kg (1.eight lb) or about 75% of capability. Thus, the utmost weight of a species determines the proportion of most at which people are usually taken for slaughter (Fig. 3). Applying this relationship throughout all listings and capping share of most at 100%, we imputed seemingly decrease and higher harvest weights for every itemizing.

Fig. 3 Maximum weight (from FishBase) determines the proportion at which aquatic animals are harvested (from FishDepend).

In aquaculture, smaller-bodied species are usually harvested at weights nearer their organic most, i.e., at the next share of their most weight. Larger-bodied species, then again, are harvested at a smaller share of their organic most. Note the big vary of percentages from lower than 1 to greater than 70%. Dots characterize particular person species with a number of consultant species recognized by their widespread title. Dark-gray line is the very best match line and shading represents the 95% confidence interval of the match (R2 = 0.64, P < 0.0001).

Table 3 Association between share of most weight at harvest and most weight for lower-bound harvest weight estimates and upper-bound harvest weight estimates.

***P < 0.0001 with 46 levels of freedom.

Last, to generate a believable vary of the variety of people farmed in 2018, we divided the full tonnage reported by FAO for every itemizing by its upper-bound harvest weight estimate (to create the decrease estimate of complete variety of people) and by its lower-bound harvest weight estimate (to create the higher estimate of complete variety of people).

Animal welfare literature protection: WOS bibliometric evaluation

Using bibliometric strategies, we decided the amount of empirical welfare work for every of the listings within the FAO aquaculture manufacturing database. We carried out a search (May 2020) for scientific papers (over all time intervals) for every scientific title in every of the primary teams of aquatic animals in our dataset utilizing Clarivate Analytics WOS, which covers >12,000 scholarly journals, together with all main science, medication, and expertise journals. Although the database has shortcomings (e.g., non-English language journals are underrepresented), it’s thought of to offer a passable illustration of worldwide mainstream scientific analysis (84).

For every itemizing related to a species or hybrid, we looked for the scientific title or widespread hybrid names together with the phrase “welfare.” If no papers had been returned, then we coded the itemizing as “no welfare papers.” When a search did return an article or extra, we appeared additional into the content material. Only papers that contained major analysis on the welfare of the species in query had been included for additional evaluation. If the authors used the phrase welfare to consult with some measure of biology, well being, conduct, or psychological/emotional state of the species in query, we included the article. We excluded evaluate papers and empirical papers that targeted on one thing apart from the welfare of people of the species in query (e.g., papers that studied a unique species or studied the welfare of the fishery). We then categorized every of the 408 FAO listings in accordance with welfare potential: “No welfare” (i.e., species-level welfare info will not be accessible, though it could possibly be), “little welfare” (i.e., 1 to Four major analysis papers have been printed on the welfare of the species in query), “5+ welfare” (i.e., 5 or extra major analysis papers have been printed on the welfare of the species in query), or “species unknown” (i.e., no species-level or hybrid-level welfare info is feasible as a result of the species is unknown/not specified by FAO).


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  2. T. Searchinger, R. Waite, T. Beringer, A. Forslund, H. Guyomard, C. Le Mouël, S. Manceron, E. Marajo-Petitzon, World Resources Report: Creating a Sustainable Food Future (World Resources Institue, 2018), p. 96.

  3. J. L. Saraiva, M. F. Castanheira, P. Arechavala-López, J. Volstorf, B. Heinzpeter Studer, Domestication and welfare in farmed fish, in Animal Domestication (Intech Open, 2019).

  4. H. F. Moed, Citation Analysis in Research Evaluation (Springer, 2005), vol. 9.

Acknowledgments: We want to thank D. Pauly, R. Froese, E. Lara, N. Boyland, and P. Brooke for his or her beneficiant time and insights in the course of the improvement of this analysis. Funding: B.F. gratefully acknowledges the Fish and Marine Animal Fund and Open Philanthropy for help. J.J.’s analysis funds from NYU offered help to C.E. Author contributions: B.F. and J.J. conceived and designed the analysis. B.F. and C.E. collected the info. B.F. analyzed the info. B.F. and C.E. wrote the paper. B.F., C.E., and J.J. reviewed and edited the paper. B.F. and J.J. offered funding acquisition. Competing pursuits: The authors declare that they haven’t any competing pursuits. Data and supplies availability: All knowledge wanted to judge the conclusions within the paper are current within the paper and/or the Supplementary Materials. Additional knowledge associated to this paper could also be requested from the authors.


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