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

Abstract

The authors contributed equally to this work.

Humane Slaughter of Edible Decapod Crustaceans

“…However, mortality is lower (but still substantial) if just one claw is removed and lower again if induced autotomy is used rather than twisting it off [ 80 ]. Even so, this is not a humane proceedure because of the problems the animals have in feeding and gaining resources [ 32 ].…”

“…Hermit crabs show long-term changes in behaviour following a shock within their shell and become less motivated to retain that shell [ 27 , 29 , 30 ], a shift that lasts for at least a day [ 31 ]. Glass prawns show prolonged rubbing and grooming of a specific antennae that has had a noxious chemical applied, but this is markedly reduced if it had been treated previously with a local anaesthetic [ 12 ], and edible, brown crabs show guarding of a wounded area after claw removal [ 32 ]. Furthermore, shore crabs hold down just one eye within the protective socket if that eye had been brushed with acid [ 33 ] and crabs with a claw injected with formalin shake and attend to that specific appendage and might autotomize it [ 34 ].…”

Assessing negative and positive evidence for animal pain

“…Another response that might have positive fitness consequences is rubbing and attending to a wound. This has been seen in wounded brown crabs (McCambridge et al 2016), hermit crabs that have been shocked on the abdomen (Appel & Elwood 2009b), and prawns (Barr et al 2008) and shore crabs (Elwood et al 2017) treated with acetic acid. These experiments show an awareness of the site of the wound and observations of wound guarding (McCambridge et al 2016), which may reduce further wounding.…”

“…We know that different taxa have very different physiology. For example, nociceptors in some taxa respond to capsaicin whereas others do not (Elwood et al 2016). Thus, it is not reasonable to expect the physiological responses of all invertebrates to be the same as those of mammals, and this applies to the way responses to noxious stimuli might be modulated.…”

Why Protect Decapod Crustaceans Used as Models in Biomedical Research and in Ecotoxicology? Ethical and Legislative Considerations

“…Dyuzen et al [ 58 ] injected formalin into an appendage of the crab, Hemigrapsus sanguineus, which then shook and rubbed the specific appendage, and reduced its use. Hermit crabs, Pagurus bernhardus , that had received electric shocks on the abdomen and had abandoned their shell showed grooming of the abdomen [ 59 ], and brown crabs that had one claw removed by twisting it off (as in fishery practice) picked at the wound and held their remaining claw over the wound when confronted by an intact crab [ 60 ]. Thus, decapods attend to the area of the body that received the noxious stimulation in a similar manner to that shown by mammals; Trade-offs between avoidance responses and other motivational requirements .…”