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May 4, 2009 10:45 pm US/Central
Good Question: Do Fish Feel Pain?
(WCCO)
With hundreds of thousands of Minnesotans poised to put a minnow on their hooks and head for the lakes, we thought we'd look at things from the fish's perspective. Do fish feel pain?
New research from Purdue University indicates that even though fish don't scream or make a pained expression, the animals do feel pain.
It's a difficult issue to study, because understanding human pain requires a certain amount of nuance. You can't take a blood test to measure pain. But over the past several decades, more scientific research has indicated signs that animals experience pain similarly to humans.
"There has been an effort by some to argue that a fish's response to a noxious stimuli is merely a reflexive action, but that it didn't really feel pain," said Joseph Garner, assistant professor of animal sciences at Purdue University. "We wanted to see if fish responded to potentially painful stimuli in a reflexive way or a more clever way."
Garner helped develop a test that found goldfish do feel pain, and their reactions to it are much like that of humans. His research was just published in the journal Animal Behaviour Science.
Garner and a doctoral student in the Norwegian School of Veterinary Science attached small foil heaters to the goldfish and slowly turned up the heat. According to Purdue, the heaters were designed with sensors that shut them off to prevent damage to a fish's tissue.
Garner organized the fish into two groups. Half were injected with morphine, a painkiller, and the others received saline. Both groups of fish showed a response at about the same temperature, which the researchers thought might indicate a reflexive response to the pain.
It's similar to a person moving a hand off a hot stove; the reaction happens before a person actually experiences pain or understands that they have been hurt.
But hours later, in their home tanks, the researchers identified major differences in the fish from the different groups.
"The fish given the morphine acted like they always had: swimming and being fish," Garner said.
"The fish that had gotten saline -- even though they responded the same in the test -- later acted different, though. They acted with defensive behaviors, indicating wariness, or fear and anxiety," said Garner. "If you think back to when you have had a headache and taken a painkiller, the pain may go away, but you can still feel the presence or discomfort of the headache."
Those with saline both experienced pain in the test, as well as responding to it, and were able to cognitively process that pain, thus causing the later fear and anxiety, according to Garner.
"The goldfish that did not get morphine experienced this painful, stressful event. Then two hours later, they turned that pain into fear like we do," Garner said. "To me, it sounds an awful lot like how we experience pain."
The findings could raise questions about slaughter methods and how fish are handled in research, according to the University. Garner said standards of care could be revisited to ensure fish are being treated humanely.
(© MMX, CBS Broadcasting Inc. All Rights Reserved.)
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