Farmed fish welfare during slaughter in Italy: survey on stunning and killing methods and indicators of unconsciousness

Abstract

Information on slaughter procedures for farmed fish in aquaculture is limited, both in Europe and in Italy, due to a general lack of field data. The aim of this study was to gather information on the procedures used to slaughter fish in Italy and to discuss them considering the WOAH and EFSA recommendations on fish welfare. Using a questionnaire survey, data were collected by official veterinarians in 64 slaughtering facilities where 20 different species of fish were slaughtered. The main species slaughtered were rainbow trout (Oncorhynchus mykiss; 29/64), followed by European sea bass (Dicentrarchus labrax; 21/64), sea bream (Sparus aurata; 21/64), Arctic char (Salvelinus alpinus; 14/64), European eel (Anguilla anguilla; 11/64), sturgeon (Acipenser spp; 11/64), common carp (Cyprinus carpio; 6/64), and brown trout (Salmo trutta fario L.; 5/64). The most applied stunning/killing methods were “asphyxia in ice/thermal shock” and “electric in water bath,” followed by “percussion,” “asphyxia in air,” and “electric dry system.” After the application of the method, the assessment of the fish level of unconsciousness was practiced in 72% of the facilities using more than one indicator, with “breathing” and “coordinated movements” the most practiced. The collected data showed a discrepancy between the available recommendations about the welfare of fish at slaughter and what is practiced in many production sites, but for many species precise recommendations are still not available.

Evaluation of non-penetrative captive bolt stunning as a method of slaughter for white sturgeon (Acipenser transmontanus)

“…Indicators can include loss of righting reflex (equilibrium), vestibulo-ocular reflex (eye compensation for tilt), and ventilation. However, these indicators can be incredibly difficult to discern in a farm setting due to the pace at which large numbers of animals are processed, and have yet to be validated for sturgeon (Clemente et al, 2023). Following a stun, sturgeon are exsanguinated in a large container with a high density of fish, making indicators like loss of vestibulo-ocular reflex and loss of ventilation difficult to observe in individual fish.…”

<b>Humane slaughter in Mediterranean sea bass and bream aquaculture: Farm characteristics, stakeholder views, and policy implications</b>

“…In Italy, a survey of 21 sea bass and sea bream farms found that none of the surveyed farms have adopted electrical stunning (Clemente et al, 2023). The slaughter methods used by the surveyed farms were "thermal shock" (20 farms) and "asphyxia in air" (one farm).…”

“…Fish producers believe that electrical stunning is more challenging for sea bass in particular, due to the fish getting stuck in the fish pumps leading to haemorrhages on their skin. A similar survey was conducted in Italy, but the negligible uptake of electrical stunning in the Italian sea bass and sea bream industry means that the survey did not produce detailed information about farmers' views on those species (Clemente et al, 2023).…”

“…Fish welfare interventions typically target one of three periods during the lives of farmed fish. Interventions can target the welfare of fish during breeding (the breeding stock or the juveniles) (Grimsrud et al, 2013;Tørud et al, 2019), the welfare of fish on-farm during the grow-out period (Pettersen et al, 2014;Stien et al, 2020), or the welfare of fish at slaughter (Lines and Spence, 2012;European Commission, 2017;Clemente et al, 2023).…”