Mutilations: Eyestalk Ablation, Declawing & Claw Nicking

‘Mutilations’ is a term used to describe procedures which destroy, remove or irreparably damage the limbs or other body parts of animals. It is often done to adapt an animal’s body to fit the environment, and quite often for economic gain. These painful procedures are usually carried out without any anaesthetic or pain relief. In animals like crabs, lobsters and prawns (decapod crustaceans), mutilations such as eyestalk ablation, declawing and claw nicking are common practice.  

Crustacean Compassion believes that no decapod crustacean should be subjected to any mutilation for any purpose, unless the procedure is undertaken by a veterinary surgeon for direct benefit to the welfare of the individual animal.

Fresh shrimp in the water for cooking.(_giant freshwater prawn).jpg

Eyestalk Ablation of Prawns and Shrimp  

Eyestalk ablation is a widespread practice of removing one or both eyestalks of breeding female shrimp or prawns, often without anaesthetic, in order to increase egg production and reproductive success, since the eyestalk contains glands which regulate the ovaries. The practice is a violent solution to the fertility problems caused by captive conditions. It involves pinching the eyestalk off, slitting with a razor blade and then squeezing out the contents, cauterising it or ligating it.  


Numerous scientists have found that the procedure appears to cause stress, trauma, and pain, with Australian vet Anthony Rowe (1) describing it as:

practices that would defy the most fundamental animal welfare standards in vertebrates, yet is routinely practiced on invertebrates.


Studies have shown that shrimp and prawns display behaviours associated with pain during and after eyestalk ablation. These include tail flicking, rubbing the affected area and flinching (2, 3). The fact that such behaviours are reduced following application of a numbing anaesthetic cream on the affected area, provides further support that this is a painful procedure (3).  


The practice of eyestalk ablation also causes serious long-term harm to these animals. It affects their: 

  • physiological, metabolic, hormonal and immune systems (4, 5, 6) 

  • sensory perception (4, 5, 6) 

  • ability to swim and move around (3) 

  • and survival rates (4, 5) 

Alternatives to Eyestalk Ablation

Reproductive success can be achieved in commercial setting without ablation and there are actually already significant initiatives underway to phase out eyestalk ablation and use other methods to increase female fertility, for example, increasing the sex ratios of males to females in the tank (7).   


There is also currently a global initiative to abolish eyestalk ablation between the South American prawn company Seajoy, the distributor Lyons Seafoods, the Global Aquaculture Alliance and the University of Stirling (8).  


In addition, some retailers are already transitioning to non-ablated prawns. Marks and Spencer claim to have eradicated it from their supply chain in all but the most exceptional of circumstances, and Waitrose claim to be phasing it out amongst their suppliers.    

Crustacean Compassion believes that eyestalk ablation - the removal or destruction of the eyestalk - of farmed shrimps/prawns or any other decapod crustacean for any purpose is unacceptable and should be prohibited.

Declawing of crabs


Declawing is the manual removal of one or both claws from a decapod crustacean, most commonly crabs. It is carried out in crabs both in fisheries and at sea.


It’s a common misconception that declawing isn’t painful, since crabs can naturally detach their own claws in response to stress or danger (this is known as natural autonomy). However, evidence shows this isn’t the case when the claws are manually removed by a human.  


Research by Patterson and 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 (9, 10, 11). 


Studies have also shown manually de-clawed crabs show behaviours indicating an awareness of the resulting wounds (such as shuddering and touching or shielding with remaining legs) not seen when claws are lost through autotomy (12), which is consistent with the view that the animals experience pain and distress as a result of de-clawing.  

Returning declawed crabs to sea 

In the UK, declawing and returning crabs to the sea is seen to promote a sustainable food source – one claw can be torn off for sale, and the crab put back into the water, where it is assumed another will grow back. Under current UK laws, fishermen can legally remove both claws and then put the animal back into the sea. However, evidence shows that crabs who are returned to sea following manual removal of one or both claws experience seriously poor welfare.  


In addition to the painful wounds caused by declawing (13), when returned to the sea the practice also seriously affects a crab’s quality of life and reduces their: 

  • ability to feed and access key food sources - which may affect the claw growing back (11, 13) 

  • ability to fight or defend themselves against predators (14)

  • ability to compete for important resources, such as territory, shelter or mating partners (14)

  • and survival rates (9, 13)

Crustacean Compassion believes that neither the practice of manually removing one or both claws from live crabs or other decapod crustaceans post harvest, nor subsequently returning them to the ocean, should be permitted. 

A live lobster has water dripping off of it as it is being placed into bins on a fishing b

Claw Nicking


The process of claw nicking involves the fracturing of the apodemes 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. 


Claw nicking is done in preparation for the transport and storage of decapods. The stressful and cramped conditions these animals are kept in increases the likelihood of fighting and cannibalism (15)(16)(17)(18). By removing the functioning of their claws, it minimises the risk of harm to other animals and handlers. 


However, despite this being done as a preventative measure, the process of claw nicking is extremely harmful. Studies have reported that the unnecessary wounds and internal tissue damage caused result in blood loss and an increased risk of infection (18)(19). Researchers have found higher rates of death in crabs that have had their claws nicked (20)(21)(22). Furthermore, it prohibits freedom to express normal behaviour as claws are essential for natural movement and activity for these animals (23)(24). 


Crustacean Compassion advocates the use of handling, storage and transport practices that avoid the need to restrict claw use in decapod crustaceans.  Due to the clear evidence of its negative impact on welfare, claw nicking should be prohibited.


  1. Rowe, A. (2018). Should scientific research involving decapod crustaceans require ethical review?. Journal of Agricultural and Environmental Ethics, 31(5), 625-634. 

  2. Diarte-Plata, G., Sainz-Hernández, J.C., Aguiñaga-Cruz, J.A., Fierro-Coronado, J.A., Polanco-Torres, A.,  Puente-Palazuelos, C. (2012). Eyestalk ablation procedures to minimize pain in the freshwater prawn  Macrobrachium americanum. Applied Animal Behaviour Science, 104 (3-4), 172-178. [10] 

  3. Taylor, J., Vinatea, L., Ozorio, R., Schuweitzer, R., & Andreatta, E. R. (2004). Minimizing the effects of  stress during eyestalk ablation of Litopenaeus vannamei females with topical anesthetic and a  coagulating agent. Aquaculture, 233(1-4), 173-179. [13] 

  4. Bae, S-H., Tomoyuki, O., Bong, J.K and Wilder, M.N., 2013. Alterations of pattern in immune response and vitellogenesis during induced ovarian development by unilateral and bilateral ablation in Litopenaeus vannamei. Fish Science, 79, 895–903. 

  5. Sainz-Hernandez, J.C., Racotta, I.S., Silvie, D. and Hernandez-Lopez. J., 2008. Effect of unilateral and bilateral eyestalk ablation in Litopenaeus vannamei male and female on several metabolic and immunologic variables. Aquaculture  283(1-4), 188-193. 

  6. Luciane M. Perazzolo, L.M., Gargioni, R., Ogliari, P. and Margherita A.A. Barracco, M.A.A., 2002. Evaluation of some hemato-immunological parameters in the shrimp Farfantepenaeus paulensis submitted to environmental and physiological stress. Aquaculture 214, 19–33 

  7. Zacarias, S., Carboni, S., Davie, A., & Little, D. C. (2019). Reproductive performance and offspring quality of non-ablated Pacific white shrimp (Litopenaeus vannamei) under intensive commercial scale conditions. Aquaculture, 503, 460-466. 

  8. Seajoy (2016), accessed 30-7-21

  9. Patterson, L., Dick, J.T.A. and Elwood, R.W., 2007. Physiological stress responses in the edible crab, Cancer pagurus, to the fishery practice of de-clawing. Marine Biology 152, 265-272 

  10. Patterson L, Dick JTA, Elwood RW. 2007. Physiological stress responses in the edible crab, Cancer pagurus, to the fishery practice of de-clawing. Marine Biology 152, 265–272. 

  11. Patterson, L., Dick, J.T.A. and Elwood, R.W., 2009. Claw removal and feeding ability in the edible crab, Cancer Pagurus: Implications for fishery practice. Applied Animal Behaviour Science 116, 302-305 

  12. McCambridge, C., Dick, J.T.A and Elwood, R.W., 2016. Effects of autotomy compared to manual declawing on contests between males for females in the edible crab cancer pagurus: implications for fishery practice and animal welfare. Journal of Shellfish Research 35(4), 1037-1044. 

  13. Duermit, E., Kingsley-Smith, P.R. and Wilber, D.H., 2015. The Consequences of Claw Removal on Stone Crabs Menippe spp. and the Ecological and Fishery Implications. North American Journal of Fisheries Management 35, 895–905. 

  14. Davis, G. E., D. S. Baughman, J. D. Chapman, D. MacArthur & A. C. Pierce. 1978. Mortality associated with declawing stone crabs, Menippe mercenaria. South Florida Research Center. National Park Service, Report T-552. 20 pp.

  15. Fotedar, S., & Evans, L., 2011. Health management during handling and live transport of crustaceans: a review. Journal of invertebrate pathology, 106(1), 143-152. 

  16. Jacklin, M., & Combes, J., 2007. The good practice guide to handling and storing live Crustacea. Sea Fish Industry Authority Publication. 

  17. Coppola, C., Tirloni, E., Vasconi, M., Anastasio, A., Stella, S., & Bernardi, C., 2019. The effects of claw ligatures in American lobster (Homarus americanus) storage: a preliminary study of haemolymph parameters. Acta Veterinaria Brno, 88(3), 329-335. 

  18. Welsh, J. E., King, P. A., & MacCarthy, E., 2013. Pathological and physiological effects of nicking on brown crab (Cancer pagurus) in the Irish crustacean fishery. Journal of invertebrate pathology, 112(1), 49-56. 

  19. Barrento, S., Marques, A., Vaz-Pires, P., & Nunes, M. L., 2010. Live shipment of immersed crabs Cancer pagurus from England to Portugal and recovery in stocking tanks: stress parameter characterization. ICES Journal of Marine Science, 67(3), 435-443. 

  20. Barrento, S., Marques, A., Pedro, S., Vaz-Pires, P., & Nunes, M.L., 2008. The trade of live crustaceans in Portugal: space for technological improvements. ICES Journal of Marine Science, 65(4), 551-559. 

  21. Johnson, L., Coates, C. J., Albalat, A., Todd, K., & Neil, D., 2016. Temperature-dependent morbidity of ‘nicked’ edible crab, Cancer pagurus. Fisheries Research, 175, 127-131. 

  22. Chartois, H., Latrouite, D., and Le Carre, P. 1994. Stocking and transportation of live crustaceans. Report of the Directorate of Live Resources. IFREMER, Brest, France. 65 pp. 

  23. Carder, G. (2017). A preliminary investigation into the welfare of lobsters in the UK. Animal Sentience: An Interdisciplinary Journal on Animal Feeling, 2(16), 19.  

  24. Esposito, G., Nucera, D., & Meloni, D. (2018). Retail Stores Policies for Marketing of Lobsters in Sardinia (Italy) as Influenced by Different Practices Related to Animal Welfare and Product Quality. Foods, 7(7), 103. Chicago.