This paper confines itself to the study of pain in fish farmed through aquaculture and its alleviation. Welfare concerns the physical and mental state of the animal (Lembo & Zupa 2009). It involves the animal’s physiological and psychological capability to cope with its environment (Lembo & Zupa 2009). Under the Five Freedoms of Animal Welfare, an animal is entitled to be free of pain, injury and disease (Lembo & Zupa 2009). This paper concerns the optimal slaughter method given that the fish is capable of experiencing pain. The paper discusses the issue of whether fish experience pain. The paper then discusses the growth of the sector and the inhuman methods of slaughtering fish. The human alternative of electrical stunning and killing of fish is then discussed with its advantages and potential problems. Using fish behaviour, the use of electrical stunning and killing of fish will be evaluated for the farming of barramundi.
Animal welfare is a complex issue that includes freedom from pain (Ashley 2006). Pain as an element of animal welfare involves understanding the subjective experience of an animal, in this case, fish (Ashley 2006). Fish are traditionally viewed as not having the capability to experience pain (Ashley 2006; Rose 2002). This position has been challenged by other researchers who claim that fish experience nociception and therefore are capable of experiencing pain (Braithwaite & Huntingford 2004; Dunlop & Laming 2005; Sneddon 2003). The possession of an opioid system in fish is strong evidence that they feel pain (Posner 2009). Given that it seems apparent that fish do feel pain, their welfare is important.
Aquaculture is an expanding industry showing strong growth of 6.2% per annum with 52.5 million tonnes of fish farmed in 2008 (FAO 2008). It is the fastest growing sector in animal-derived food (Stevenson 2007) contributing 40% of the total global fish production (FAO 2008). One of the methods used to slaughter fish is to asphyxiate the fish by removing them from water. When a fish is removed from water their gills collapse preventing oxygen exchange. At 20C, a rainbow trout removed from water will lose brain function in 9.6 minutes and at 200C in 2.6 minutes (Stevenson 2007). A review of this slaughtering method by the Scientific Panel on Animal Health and Welfare of the European Food Safety Authority (EFSA 2004) concluded that this approach is inhumane.
Another approach to slaughtering fish is to remove the fish from water and place them in bins with ice (Stevenson 2007). It takes longer for fish to die under this approach (EPSA 2004). The European Food Safety Authority (EPSA 2004) recommended that this approach should not be used as the fish is immobilised but still conscious. Governments have not acted in making this method illegal (Stevenson 2007). This approach is still very common in the industry (Stevenson 2007).
There are many sources of pain in the farming of fish. The slaughter techniques for fish are often...