The killing of farm animals can cause pain, distress, fear or other forms of suffering even under the best available technical conditions.
The Lisbon Treaty established that animals are sentient beings. Reg. EC 1099/09 of the European Council establishes specific implementing rules for the protection of welfare during the killing of farm animals, stipulating that animals should be spared avoidable pain and suffering.
Since caught or farmed fish are also recognized as sentient beings, the guiding principle that they be spared avoidable pain, distress or suffering during slaughter and related operations at the time of slaughter remains applicable.
Pisces and wellness: what issues?
Fish have physiological differences and are culled in a very different context than terrestrial animals. The European Commission has recommended identifying separate standards for protection during the slaughter of fish products (EC Reg. 1099/09).
Due to physiological and slaughtering differences, however, fish species remain excluded from many of the recommendations governing animal welfare. In fact, the main animal welfare enforcement issues in fish are ineffective stunning methods and killing methods that do not respect animal welfare.
Most of the methods of killing used (percussive method, free projectile followed by a killing method such as gill cutting) expose fish species to considerable suffering for a prolonged time, and some of the practices they undergo, such as boiling in shellfish, can cause avoidable pain and distress.
The neurophysiological criteria of sensience
Mammals, birds, and fish (including commercial fish species) possess complex neurological substrates that support the capacity for pain sensitivity and conscious experience. Both abilities are closely related, as feelings are conscious experiences in the most basic sense of consciousness.
The normative principle behind the concept of animal welfare centers on two main concepts: sentience and nociception.
Sentience is the animal’s ability to experience feelings, both positive (comfort, excitement) and negative (pain, distress or harm).
Nociception is the physiological system that detects actual or potentially noxious stimuli through the activation of nociceptors (sensory receptors in the peripheral somatosensory nervous system) that are able to transfer and encode painful stimuli. Even being distinct, the concepts of sentience and nociception are closely related. States of anxiety, fear, hunger, thirst, coldness, discomfort and boredom are recognized as negative affective states.
The 2022 publication of the Birch report reviewed a substantial collection of neurophysiological studies carried out in fish species such as cephalopods (octopus, squid, cuttlefish, nautilus) and crustaceans (crabs, lobsters, shrimp) by identifying eight sensitivity criteria and using five confidence levels for each criterion (Birch et al., 2021 (Tab. 1-2).
Cephalopods and crustaceans are sentient beings
In cephalopods, who meet seven of the eight physiological sensitivity criteria stated in the report, there is evidence of afferent sensory neurons in response to noxious stimuli, molecular markers of nociceptors, and brain areas capable of integrating different types of information (e.g.the vertical lobe of cephalopods is the center responsible for learning and memory).
In addition, the presence of endogenous neurotransmitters and receptors and the ability to consciously respond to noxious stimuli to which cephalopods are subjected under experimental conditions is demonstrated. For example, they exhibit care and protective behaviors by wrapping their tentacles around the injured area or attempt to ward off the noxious stimulus when injured. In addition, when exposed to a noxious stimulus, they learn to move to special chambers where they can self-administer a local anesthetic.
Also in crustaceans there is a developed nociception system and multiple brain areas (central complex, hemiellipsoid bodies and accessory lobes) capable of integrating information.
In lobsters and crabs, the action of endogenous neurotransmitters (dopamine and octopamine) highlights the ability of crustaceans to mediate learning function toward aversive/attractive stimuli, while the neurotransmitter serotonin mediates stress responses.
Some crustacean species respond to physiological criteria of associative learning. For example, under experimental conditions, they are able to weigh the value of a harmful stimulus (injury) against that of the opportunity for reward (food). Crabs exhibit wound self-protection behaviors.
Welfare in cephalopods at the time of capture
Catching techniques and timing greatly affect the welfare of the cephalopods, which are usually transported aboard the ship already dead or near death. Changes in salinity can cause discomfort, stress, and death. Improper handling causes physical trauma such as injury or detachment of the coat from the head.
When catching methods involve nets, the main welfare risk is the stress of catching and the danger of suffocation of cephalopods overpowered by excessive catch weight. Collision with other animals or parts of the net routinely causes skin ulcerations or fin lesions, which promote bacterial growth and infection.
Injuries can then worsen if disembarkation is delayed by hours or days. Stress conditions related to confinement in a small space induce in octopuses and cuttlefish the manifestation of fighting behaviors and cannibalism between individuals of different sizes, if insufficiently fed.
In cephalopods, the question is whether a method of killing that prolongs suffering because of the time required before loss of consciousness can be considered acceptable.
In cephalopods, there is currently no environmentally friendly and widely applicable method of culling that can reduce pain sensitivity and the perception of feelings of distress in the stage immediately preceding death.
Alternative experimental methods such as the use of anesthetics would render the cephalopods unfit for human consumption. Similarly, mechanical methods involving jugulation or drilling of the brain require experienced operators and are inapplicable on a large scale.
What about the welfare of shellfish?
The main issue of crustacean welfare is the need for a stunning phase before culling. Practices involving freezing, asphyxiation, or the use of CO2 as killing methods are considered crudely, because they take too long (more than an hour) to achieve crustacean death.
Electrical stunning is considered a ‘humane’ method, but the priority is to define the application of electrical parameters modulated according to the different species, size and stage of development of crustaceans within the maximum time limit of ten seconds, a time considered short enough to reduce suffering before death.
In households and restaurants, immersing live shellfish in boiling water is considered a highly critical practice from an animal welfare perspective.
Boiling, in the absence of a prior stunning method, causes severe suffering, which crustaceans manifest with physiological behaviors of discomfort, such as uncoordinated movements and escape attempts. While in small crustaceans (e.g., shrimp) boiling causes a period of up to 2 minutes of continuous sensation and suffering before death, in larger crustaceans the period extends beyond 2.5 minutes. This is demonstrated by the intense neuronal activity that continues up to 30-150 seconds after immersion in species such as lobster and cuttlefish. On the other hand, the practice of gradually increasing the water temperature after the crustaceans are submerged, with the intention of reducing suffering, is not recommended, as it achieves the opposite effect.
Welfare of fish and fish species, prospects
The way reg. EU 1099/09 for the welfare of fish species appear limited. Therefore, the goal of European policy should be to include in the scope of welfare legislation all animals for which there is sufficient evidence of susceptibility based on specific standards.
The neurological and behavioral criteria of the Birch report define important indicators of pain sensitivity in fish species, such as
(a) the ability to produce substances with pain-relieving effect,
(b) the capacity for motivational trade-offs, whereby the animal behaves by evaluating choices to avoid a harmful stimulus,
(c) the ability to avoid situations or places where he has previously come in contact with harmful stimuli.
As opposed to simple nociception, these criteria represent valid indicators of pain sensitivity insofar as they require the ability of brain areas to integrate tissue damage information with other types of information and that of making such information available for the mechanisms of motivation, decision making, memory, and learning.
Fish welfare during slaughter is more than just an ethical issue considering that, in a One-Health approach, food safety must also include the concept of welfare protection in all animal species.
Raffaella Mercogliano
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Professional journalist since January 1995, he has worked for newspapers (Il Messaggero, Paese Sera, La Stampa) and periodicals (NumeroUno, Il Salvagente). She is the author of journalistic surveys on food, she has published the book "Reading labels to know what we eat".
