Everyone knows what factory farming is.

When hearing this term, most people would immediately think about chickens or pigs. Those who may know a bit more about animal exploitation may be aware that fishes are also factory-farmed, especially salmons and trouts. Vegans, who recognise that all animals are sentient beings, and know that humanity has been exploiting invertebrates for millennia, would likely be aware that insects such as silkworms, bees, or crickets have been also factory-farmed. However, very few people know about the factory farming of crustaceans. Most people assume that if they eat lobsters, shrimps, crabs, or crayfish, they were all captured from the wild, but many may have been born and bred in captivity. So many that, in the case of shrimps and prawns, factory-farmed individuals are now the majority consumed as food by people. 

Crustaceans farming is a type of factory farming where these aquatic invertebrates suffer the same type of abuse that any other factory-farmed animal is forced to endure. This article will tell you a bit about this often-ignored branch of animal agriculture.

Who Are the Crustaceans?

(Royalty-free stock photo ID: 1127657957) Lobster under water on a rocky bottom

Crustaceans are a type of Arthropod, and like all Arthropods (such as insects, arachnids, myriapods, etc.) they are invertebrate animals with an articulated external skeleton. All crustaceans belong to the subphylum Crustacea and form a diverse group that includes decapods (lobsters, shrimps, prawns, and crabs, the most well-known type characterised for having ten legs), seed shrimp, branchiopods, fish lice, krill, remipedes, isopods, barnacles, copepods, amphipods, and mantis shrimps.

Most crustaceans are aquatic (common exceptions are woodlice and sandhoppers), and most live in marine environments, but some in freshwater too (such as crayfishes, who are not really fishes despite their name). Most can swim or walk, but some are sessile, such as barnacles. They have sophisticated internal digestive and circulatory organs, as well as various sensory organs such as sensitive antennae and complex eyes. They have a central nervous system that includes a brain formed by ganglia close to the antennae, and a collection of major ganglia is found below the gut (even barnacles have a distinctive brain in their larva form, that is free moving as opposed to the adult form).

The body of a crustacean is composed of segments, which are grouped into the cephalon or head, the pereon or thorax, and the pleon or abdomen. The head and thorax may be fused together to form a cephalothorax. Their exoskeletons are made of hard fibrous chitin–protein tissue containing calcium carbonate minerals.

Crabs’ and lobsters’ eyes are set on stalks which enables them to see all around and in different directions at once. Peacock mantis shrimps (Odontodactylus scyllarus) have the most complex set of eyes in the Animal Kingdom. Each eye contains 12 photoreceptors that allow them to sense different types of colour (human eyes only have three types of light-sensitive cells for seeing red, blue, and green), and they can see polarised light. Scientists believe that mantis shrimp take all the visual information they see into their brains at once without processing it, allowing them to react to their surroundings as quickly as possible. Their independently roaming eyes and trinocular vision explain why they are so efficient predators.

Both crabs and lobsters sense the world through hairs on their body which are sensitive to touch, sound, smell, taste, and temperature. Many crustaceans communicate by flapping their pincers or drumming their claws. Spiny lobsters are thought to be social animals and gather in groups of 12 or more, migrating in long chains across the ocean floor, up to 50 lobsters at a time.

There are 67,000 described species of crustaceans, and many are eaten by people. The vast majority of those eaten are decapod crustaceans, such as crabs, lobsters, shrimps, crawfish, and prawns. Over 60% by weight of all crustaceans caught for consumption are shrimp and prawns, nearly 80% of which are produced in Asia (China alone produces nearly half the world’s total).  

Which Crustaceans Are Farmed?

Shutterstock (Royalty-free stock photo ID: 1932000554)Fresh shrimp prawn life on the pond, Shrimp farm for sales to the market

About 100 species of crustaceans are farmed. Shrimps and prawns are the most often farmed, with species of the genera Litopenaeus, Penaeus, Fenneropenaeus, Farfantepenaeus, Macrobrachium, and Pandalus being the most common. Following are crabs, with species of the families Portunidae, Grapsidae, Ocypodidae, and Varunidae. The third type are crayfishes, from the families Astacidae, Cambaridae, Parastacidae, and Cheraxidae. Lobsters from the families Nephropidae, Palinuridae, and Scyllaridae are also farmed. Finally, barnacles of the subclass Cirripedia are farmed mainly in Spain and Portugal.

The top ten farmed crustacean species ranked by the value of their respective industry are Whiteleg shrimp or Pacific white shrimp (Litopenaeus vannamei, or Penaeus vannamei ), Giant tiger prawn (Penaeus monodon), Indo-Pacific swamp crab (Scylla serrata),  Indian white prawn (Fenneropenaeus indicus), Swimming crab (Portunus trituberculatus), Kuruma prawn (Marsupenaeus japonicus), Fleshy prawn (Fenneropenaeus chinensis), Metapenaeus spp. (M. monoceros + M. ensis), Mud crab (Scylla paramamosain), and Blue shrimp (Litopenaeus stylirostris).

Virtually all farmed shrimp are of the family Penaeidae, and just two species, Whiteleg shrimp (Penaeus vannamei) and Giant tiger prawn (Penaeus monodon) account for roughly 80% of all farmed shrimps. Whiteleg shrimp are native to the eastern Pacific Ocean, from the Mexican state of Sonora to as far south as northern Peru. The Giant tiger prawns’ natural distribution is the Indo-Pacific, from the eastern coast of Africa and the Arabian Peninsula, as far as Southeast Asia, the Pacific Ocean, and northern Australia.

Portunus trituberculatus (known as the horse crab, the gazami crab, or the Japanese blue crab) is the most widely fished species of crab in the world, with over 300,000 tonnes being caught annually, 98% of it off the coast of China. Horse crabs are found from Hokkaidō to South India, throughout maritime Southeast Asia and south to Australia. 

According to The State of World Fisheries and Aquaculture 2020 report by the United Nations Food and Agriculture Organisation, in 2018, 9.4 million tonnes of crustaceans’ bodies were produced in factory farms, with a trade value of USD 69.3 billion. About 6 million tonnes were from marine and coastal aquaculture, while about 4 million tonnes were from inland aquaculture. In 2015, the total was about 8 million tonnes (5 million from marine facilities), and in 2010, it was 4 million tonnes (3 from marine facilities), showing that in eight years the production has almost doubled. In 2022, the production of crustaceans reached 11.2 million tonnes.

In 2018, the world’s fisheries captured 6 million tonnes of crustaceans from the wild, and if we add these to the 9.4 million tonnes produced that year by aquaculture, this means that 61% of the crustaceans used for human food come from factory farming. The reality of farming crustaceans is that this has become the most common source of crustaceans as human food in the world.   

As in the case of fishes, all these values are recorded in weight, not in the number of individuals killed. However, there have been some estimations of actual numbers. The number of decapod crustaceans killed in recorded aquaculture production in 2017 has been estimated to be 43-75 billion crayfish, crabs, and lobsters, and 210-530 billion shrimps and prawns. Considering that about 80 billion land animals are slaughtered for food every year (66 million of which are chickens), this means that most victims of factory farming are crustaceans, not mammals or birds — and every year this difference has been increasing, perhaps because despite the number of vegans may have increased, also the number of meat-eaters who have become pescatarian and eat more aquatic animals now have increased. 

The Crustacean Farming Industry

Aerial view of the prawn farm By Nguyen Quang Ngoc Tonkin via Shutterstock (Royalty-free stock photo ID: 1720947835)

Like in the case of farming fishes such as salmons, commercial aquaculture of any species is a relatively recent phenomenon. The farming of crustaceans started on a small scale in southeast Asia (from India to the Philippines, through Malaysia, Thailand and Indonesia), but commercial shrimp farming at a global scale began in the 1970s. Global production first reached more than 1 million tonnes at the beginning of this century. About 75% of farmed shrimps are produced in Asia, in China and Thailand (which is the largest exporter), and the rest in Latin America — Brazil being the largest producer there. 

Most factory-farmed shrimps and crabs are produced in Asia, but regarding freshwater species, freshwater prawns and Chinese river crabs are mainly produced in China, but freshwater farming of crayfish is most common in the US, Australia, and Europe.

The process of farming crustaceans is divided into the following stages:

  1. “Broodstock” and Hatchery: In crustacean farming, the term “broodstock” refers to mature adult crustaceans kept for breeding purposes. These individuals are selected based on their health, size, and genetic characteristics. They are usually maintained in controlled environments, such as tanks or specialized breeding facilities, where the water quality, temperature, and other parameters can be regulated to promote reproduction. Once they produce eggs or larvae, they are collected and transferred to hatcheries for further rearing.
  2. Larval Rearing: Crustaceans typically have complex life cycles that involve a larval stage before they metamorphose into adults. Larval rearing involves providing the right environmental conditions for the larvae to grow and develop. Larvae are usually very small and sensitive to water conditions.
  3. Nursery and Grow-out: After the larvae go through several molting stages (shedding the outer skeleton to be able to grow a bigger one) and become juveniles, they are transferred to nursery systems. Once the crustaceans reach a certain size and maturity, they are moved to grow-out systems, which can be large-scale ponds, raceways, or other captive environments. Crustaceans are fed a combination of natural food sources, such as algae, zooplankton, or small aquatic organisms, as well as formulated feeds that contain proteins, carbohydrates, fats, vitamins, and minerals. 
  4. “Harvesting” and Processing: When the crustaceans reach the desired size, they are killed (which the industry calls “harvesting”) by different methods depending on the species and country.

The Suffering of Crustaceans in Aquaculture

White shrimp from mature farms are transported to a cooling tank and prepared for export to the partner country. via Shutterstock Royalty-free stock photo ID: 1071103556

All the crustaceans bred in factory farms spend their lives in captivity in cramped conditions (which is what factory farming of any species is based on). Keeping many animals in a small space can lead to increased aggression, competition, cannibalism, and stress.

Disease outbreaks are common in factory farming of any type, and crustacean farming is not an exception. Diseases can cause high mortality rates, stunted growth, deformities, and impaired immunity. Environmental stressors, such as acute or prolonged changes in water temperature, PH, salinity, dissolved oxygen, nitrites, and carbon dioxide, can also be a cause of suffering because these can affect the general physiology, metabolism, and immune function of crustaceans. Handling and transport, which can cause injuries, infections, and stress, can also make farmed crustaceans suffer. 

One of the specific cruel practices of crustacean farming that causes suffering would be eyestalk ablation, which is removing or constricting the eyestalks of female shrimps to induce maturation and spawning. Ablation of eyestalks is a crude method of hormonal manipulation. It involves cutting, cauterising, or tying of one (unilateral) or two (bilateral) eyestalks to reduce the level of gonad inhibiting hormone (GIH/MO-IH) which is produced by the X-organ and sinus gland complex situated in the optic ganglia of the eyestalk. Numerous scientists have found that the procedure appears to cause stress, trauma, and pain, with Australian vet Anthony Rowe describing it as, “practice that would defy the most fundamental animal welfare standards in vertebrates, yet is routinely practised on invertebrates.” Due to the cruelty of this practice, there are a few facilities in Brazil, Colombia, Ecuador, México, and Thailand that are no longer using eyestalk ablation. 

Another type of mutilation crustaceans may endure is declawing, which is the manual removal of one or both claws from a decapod crustacean, most commonly crabs. Research by L. Patterson and R. Elwood have shown that there is an increased stress response and higher mortality in crabs who have been declawed by humans, versus crabs who have been encouraged to shed their own claws. Also, there is another process called claw nicking which involves the fracturing of the apodemes (internal ridges from the exoskeleton of most arthropods that support the internal organs or provide points of attachment for the muscles) and the cutting of tendons in the dactyls of claws to prevent functioning. It is performed on large decapod crustaceans such as crabs and lobsters. Researchers have found higher rates of death in crabs who have had their claws nicked.

Human health can also be negatively affected by crustacean farming, as the animals can be contaminated with domestic sewage that contains human pathogenic bacteria and viruses. In shrimp farming, the main potential food safety hazards are zoonoses, chemical contamination, and veterinary drug residues. There is also an environmental cost caused by untreated effluent from shrimp farms as it is known to promote plankton blooms if directly discharged into natural water sources.

All the crustaceans in farms will eventually be killed, but the methods may vary a great deal. These are the most common methods of slaughtering crustaceans

  • Spiking: This is a method of killing crabs by inserting a sharp object into their ganglia located under the eyes and at the rear of the carapace. This method requires skill and accuracy, and it can cause pain to the crabs.
  • Splitting: This is a method of killing lobsters by cutting them in half with a knife along the midline of the head, thorax, and abdomen. This method can also cause pain.
  • Chilling in Ice Slur. this is used in tropical species of marine crustaceans susceptible to colder temperatures, as chilling in ice slurry may render them unconscious. Generally, a minimum of 20 minutes of immersion in ice slurry is required to induce unconsciousness.
  • Boiling. This is a common method of killing crabs, lobsters, and crayfish, but it is considered inhumane by most people as it obviously causes prolonged suffering and pain to the animals. 
  • Carbon-Dioxide Gassing. Crustaceans are also killed by increasing the concentration of carbon dioxide in water, but the animals suffer distress by this method.
  • Drowning with fresh water. This means killing marine crustaceans by altering salinity, effectively “drowning” saltwater species in freshwater by osmotic shock.
  • Salt baths. Placing the crustaceans in water that has a high concentration of salt also kills them by osmosis shock. This may be used for freshwater crustaceans. 
  • High pressure: This is a method of killing lobsters by subjecting them to high hydrostatic pressure (up to 2000 atmospheres) for a few seconds. 
  • Anaesthetics. It is rare, but the use of chemicals to kill crustaceans has also been practised. AQUI-S, a clove oil-based product, has been approved for the killing of aquatic animals for human consumption in New Zealand, Australia, Chile, South Korea, and Costa Rica. 
  • Electrical stunning. A study in 2010 found electrical stunning to be the most efficient killing method for edible crabs when compared with common commercial methods such as boiling, chilling, freezing, gassing, and immersion in salt.

Most commercial methods of killing are likely to cause considerable suffering. Spiking, splitting, and high-pressure killing seem likely to be less inhumane since the killing process is much shorter, but since they still take time and cause distress and pain, they cannot be considered humane. In any event, there is no such thing as “humane” slaughter of an animal who wants to live, so there is no “ethical” way to farm crustaceans. 

Crustaceans Are Sentient Beings 

Mealy crab By Peeranat Thongyotee via Shutterstock (Royalty-free stock photo ID: 288285827) Mealy crab (Thaipotamon Chulabhorn)

Crustaceans, as the majority of members of the Animal Kingdom (except sea sponges), are sentient beings. This means they can experience positive, neutral, and negative experiences because they have sophisticated senses that inform the crustaceans about their environment and a nervous system that allows them to process this information and behave appropriately (normally by moving). However, compared with other invertebrate animals whose sentience may be questioned, most scientists do agree that most crustacean species are sentient as there has been a lot of research to prove it (some of it quite unethical, in my view). 

For instance, research from Barr et al. (2008) found the presence of opioids and opioid receptors in crabs, leading them to postulate that some crustaceans may possess an analgesic system like that found in vertebrates. Crabs have shown memory of aversive stimuli and learnt to avoid electric shocks by refraining from entering the environment associated with the painful stimulus, rather than simply escaping from it. Research from 2015 found that a painful situation triggers a stress response in crabs. This, combined with other findings, such as decapods changing their long-term behaviour after a painful incident, demonstrates that decapods are capable of experiencing pain. Other studies have shown that crustaceans rub and hold an injured area, as well as limp and reduce the use of injured body parts, also suggesting that they feel pain.

A 2005 report by the European Food Safety Authority (EFSA) for the European Commission concluded that the largest of the decapods have a pain system and complex cognitive capacity and therefore were assigned Category 1 status (animals who can experience pain and distress). The report states, “The largest of these animals [decapod crustaceans] are complex in behaviour and appear to have some degree of awareness. They have a pain system and considerable learning ability. Little evidence is available for many decapods, especially small species. However, where sub-groups of the decapods, such as the prawns, have large species which have been studied in detail they seem to have a similar level of complexity to those described for crabs and lobsters.”

In the most progressive countries (New Zealand, Norway, Switzerland, UK, Canada, and EU nations), species increasingly acknowledged to be legally sentient for legislation purposes include now some invertebrates, in particular cephalopods (a type of mollusc which includes octopus, cuttlefish, and squid), and crustacean decapods. This does not mean that only decapods are sentient crustaceans, but what it means is that their sentience is so obvious that there are no longer excuses to not recognise officially them as sentient beings. 

Decapod crustaceans are also included as protected animals in the UK legislation that deals with animals in scientific procedures. Additionally, in 2022, octopuses and decapod crustaceans became the first invertebrates to be officially considered sentient beings under UK law — although this is mostly symbolic as the Animal Welfare Act 2006, the law that would protect farmed crustaceans, does not include them.    

There are even animal protection organisations exclusively dedicated to the protection of crustaceans. Since 2020, Crustacean Compassion has been campaigning for the humane treatment of crabs, lobsters, and other decapod crustaceans in the UK. They engage with legislators and policymakers to strengthen and enforce animal welfare laws and policies, and they seek to educate both the public and policymakers on the science of decapod crustacean sentience and their humane treatment.

Crustaceans are sentient beings, and billions of them are farmed every year. Together with the insects, their fellow Arthropods, they are now the most common factory-farmed animals in the world.  

That’s the reality of farming crustaceans.

“Originally from Catalonia, but resident in the UK for several decades, Jordi is a vegan zoologist and author, who has been involved in different aspects of animal protection for many years. In addition to scientific research, he has worked mostly as an undercover investigator, animal welfare consultant, and animal protection campaigner. He has been an ethical vegan since 2002, and in 2020 he secured the legal protection of all ethical vegans in Great Britain from discrimination in a landmark employment tribunal case that was discussed all over the world. He is also the author of the book, ‘Ethical Vegan: a personal and political journey to change the world’.