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Climate change is altering the sensory systems of fish and can even make them swim towards predators, instead of away from them, a study warns.

The research, conducted by marine biologists at the University of Exeter shows that rising CO₂ impacts on the brain’s signal processing of fish, thus disrupting their senses, including their smell, hearing and vision.

CO₂ levels are predicted to be 2.5 times higher in the oceans by the end of this century.

The report authors believe that fish farms may be the key to establishing the long-term impact of CO₂ on marine life.

Drs Robert Ellis and Rod Wilson, along with a Chilean colleague, point out in a research report published in the journal Global Change Biology that farmed fish often live in CO₂conditions 10 times greater than their peers in the wild.

According to the scientists, further study of farmed fish may be crucial for understanding how aquatic species will evolve to climate change.

“Aquaculture may provide an ‘accidental’ long-term experiment that can help climate-change predictions,” Dr. Ellis said.

“There is the enticing possibility that fish and shellfish previously grown in high CO₂aquaculture conditions over multiple generations can offer valuable insights regarding the potential for aquatic animals in the wild to adapt to the predicted further increases in CO₂,” the researcher stressed.

The aquaculture industry may also benefit from what the climate change scientists study too. The abnormal behaviour seen in wild fish may not matter in farmed fish, as they are provided with abundant food and shelter and they have no predators to avoid. However, while extremely high CO₂ can reduce digestion efficiency in cod, recent research suggests that relatively small increases in CO₂ may actually act as a growth stimulant in some fish.

“Our research will allow fish farmers to optimise conditions, and specifically CO₂ levels, to improve growth and health of their fish, profitability and the long-term sustainability of the industry,” Dr. Wilson explained.

“This is really important given that aquaculture is the only way we will increase seafood production to feed the growing human population, particularly given wild fish stocks are overexploited,” the researcher concluded.

Source: Fish Information and Services (FIS)