It is a long held traditional belief that fish do not feel pain the way that humans do, largely due to the fact that they have unsophisticated nervous systems, and lack brains complex enough to generate a conscious awareness of pain. However, after extensive research, fish biologists around the world have put together considerable evidence to indicate that fish do, in fact, feel pain.
The jury is still out when it comes to determining whether fish actually do consciously experience pain, however studies demonstrate that fish can change behavior and physiology in response to high temperatures, intense pressure, and corrosive chemicals. In one study, where rainbow trout were injected with acetic acid into their lips, scientists reported unusual changes in behaviour – including faster breathing, rocking back and forth on the bottom of the tank, rubbing their lips against the gravel and the side of the tank, and taking twice as long to get back to feeding. This is in contrast to fish that were just injected with saline, which did not demonstrate any odd behaviour at all. Fish that were injected with both acetic acid and morphine also exhibited some of these unusual behaviors, but to a lesser degree.
While these studies demonstrate a behavioural, hormonal or physiological reaction to a seemingly painful impulse, it is impossible to know whether this is a conscious awareness of pain or an unconscious processing of impulses and reflexes in response to external stimuli.
Despite some evidence that fish react to pain, it is highly unlikely that they will be afforded the type of legal protection that is commonly given to farm animals, laboratory animals, and domesticated pets throughout the world.
On a global scale, The United Kingdom has some of the most advanced animal welfare laws in place. In countries such as Canada and Australia, animal welfare legislation varies from one state to the next, and in Japan, relevant legislation places little importance on the rights of fish. In the United States, animal welfare regulations do not include fish, amphibians and reptiles.
In some of the more progressive countries, such as the United Kingdom and Norway, human slaughter methods, including knocking fish unconscious with either a quick blow to the head or direct electrical currents, then piercing their brains or bleeding them out, are now being used in fish farms. In Norway, these practices have even been trialed in commercial fishing vessels, to determine whether these methods are viable out at sea.
In the United States, a new and unique type of humane fishing is being trialed by two fishermen, aboard their customised vessel named Blue North. The boat, at 58-meters in length and which can carry a crew of 26, and 750 tonnes in weight, harvests Pacific cod from the Bering Sea. In a temperature-controlled room located in the middle of the boat, away from the elements, the crew retrieve fish one at a time through a hole in a moon pool – allowing them more control over fishing than they would normally achieve in an ordinary fishing vessel. Immediately after the fish is brought to the surface, it is stunned with 10 volts of electricity, and then bled out. This method is believed to greatly reduce stress, panic and injury.
While these studies are insightful, there is still no concrete proof to indicate that fish experience conscious pain. A discovery like this would no doubt have wide-ranging consequences for the fishing industry, recreational fishers and human-kind.