August Linnman via Wikimedia Commons

Despite traveling in schools, fish usually are regarded as unintelligent creatures (Don’t you groan at me; that was gold.) However, a new study by Culum Brown of Macquarie University in Sydney, suggests that some fish have higher cognitive function than previously believed. If fish sentience is higher than we thought, there are implications in animal husbandry for fish used in the laboratory and would likely affect the fishing industry as well. Brown analyzed the current body of research surrounding fish cognition and sensory perception. His paper was published in the journal Animal Cognition. The paper was funded by The Someone Project, an animal rights group.

Of the estimated 62,000 species of vertebrates on the planet, half of them are fish. Fish are also a common model organism in laboratory testing, second only to rodents. Globally, humans eat fish more than any other animal. Despite the large diversity and importance of these creatures, they aren’t regarded as highly as other vertebrates, particularly mammals. This is partially due to the widely accepted idea that fish don’t feel pain and are fairly dumb creatures with little awareness of the world around them. As it turns out, certain fish may have traits that are not entirely dissimilar to humans.

“Although scientists cannot provide a definitive answer on the level of consciousness for any non-human vertebrate, the extensive evidence of fish behavioral and cognitive sophistication and pain perception suggests that best practice would be to lend fish the same level of protection as any other vertebrate,” Brown stated in a press release. “We should therefore include fish in our ‘moral circle’ and afford them the protection they deserve.”

Here are some highlights from the research:

-Though it used to be assumed that only humans had cerebral lateralization, the ability to favor certain hemispheres for certain tasks, permitting the ability to multitask. Many associate this ability with higher thinking, and the phenomenon has been shown to exist in a number of other organisms, including fish. Brown argues this allows fish to "perform multiple complex tasks simultaneously. ”

-Fish can be trained to recall the location of objects by obtaining clues from the landscape.

-The myth that goldfish have a three-second-long attention span has been long-since debunked, and fish have been shown to have "have excellent long-term memories” for a number of factors.

-A school of fish isn’t just an aimless group swimming around. Fish can have complex societies where certain traditions can be passed down to other fish, which also shows the capacity to learn. Certain fish have also been shown to demonstrate traits of cooperation and reconciliation within the group.

-Tool use is typically regarded as the gold standard for intelligence, and it turns out that some fish can be added to that list. For example, certain cod species were fitted with a dorsal tag. The fish were able to use the tag by swimming up to a self feeder that had a string hanging down to trigger the release of food. The fish learned how to swim up to the string and catch it on their dorsal tag, causing the food to be released.

Brown also argues that fish indeed feel pain, as "it would be impossible for fish to survive as the cognitively and behaviorally complex animals they are without a capacity to feel pain." However, a paper published in August 2013 suggests that fish perceive pain differently than humans, due to the lack of a neocortex in fish. Many species of fish also lack certain nerve fibers associated with pain in humans. The paper cautions against anthropomorphizing the feelings of fish based on perceived amounts of pain. While their paper doesn’t definitively prove fish don’t feel pain, it does speak to the fact that there is much about fish cognition that we don’t understand. Future research among ichthyologists will seek to resolve these discrepancies in order to understand the full cognitive capabilities of this amazing, diverse group of animals.

 

 

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