Climate change makes fish swim towards, not away from predators

Climate change makes fish swim towards, not away from predators

In a recent study, scientists find that climate change is disrupting the sensory systems of fish and can impair their survival instincts.

The finding is published in Global Change Biology. Marine biologists from the University of Exeter conducted the study.

Previous research about the impact of rising CO2 has shown it can disrupt the senses of fish including their smell, hearing and vision.

Now the finding shows that high CO2 levels can impair the way fish behave, including making them swim towards predator smells instead of away and even ignoring the sounds that normally deter them from risky habitats.

These abnormal behaviors are caused by the increased CO2 level in the oceans, which changes how the brain processes signals from sensory organs.

Fish farms may be one reason that cause the long-term impact of CO2 on marine life. Farmed fish often live in CO2 conditions 10 times higher than their wild cousins.

Researchers suggest that aquaculture (e.g., fish farming) may provide an ‘accidental’ long-term experiment that can help predicate climate change.

Fish and shellfish grown in high CO2 aquaculture conditions over multiple generations can offer valuable information about how aquatic animals in the wild adapt to the high CO2 environment.

The aquaculture industry may also benefit from what the climate change scientists study too. The abnormal behavior seen in wild fish may not matter in farmed fish, which have abundant food and shelter and no predators to avoid.

But while extremely high CO2 can reduce digestion efficiency in cod, relatively small increases in CO2 may act as a growth stimulant in some fish.

Future research will allow fish farmers to optimize conditions to improve growth and health of their fish. This can increase profitability and the long-term sustainability of the industry.

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Citation: Ellis RP, et al. (2016). Lessons from two high CO2 worlds – future oceans and intensive aquaculture. Global Change Biology, published online. DOI: 10.1111/gcb.13515.
Figure legend: This image is for illustrative purposes only.