Science 3 min read

Climate Change Endangers 60 Percent of Fish Species

Rich Carey /

Rich Carey /

It’s no secret that climate change threatens the health of fish species. One of the direct effects of climate change is increased temperatures, as well as the frequency and intensity of heatwaves.

Depending on its duration, heat stress can lead to oxidative stress and immune suppression. Along with causing more infections, these health issues can eventually lead to the death of the aquatic creatures.

Previous analysis suggests that only 5 percent of the world’s fish species will struggle to adapt to 5°C of global warming. However, these studies were based on adult fishes alone.

Now, a new study has considered the different stages of fish’s lives and reached a more dire conclusion.

It turns out that 60 percent of fish species on the planet could become extinct by 20100 due to 5°C of global warming. Even if we manage to meet the Paris Agreement goal of 1.5°C, it would still be too hot for 10 percent of fish species.

Speaking to New Scientist, one of the researchers from the Alfred Wegener Institute in Bremerhaven, Hans-Otto Pörtner said:

“We can say 1.5°C is not paradise; there will be changes. But we can limit those changes if we manage to stop climate change. Fish are so important for human nutrition, so this study makes a strong case for protecting our ecosystems and natural environments.”

The researchers explained how they reached this conclusion in their published article in AAAS.

Analyzing the Life-Stages of Fish Species

For the study, the researchers analyzed existing studies on the heat tolerance of 649 species of freshwater and marine fish species.

Unlike previous studies, the team considered the life phase of fishes that have been mainly ignored. These include spawning and non-spawning adults and larvae, as well as embryos.

This led to the conclusion that spawners and embryos cope with a smaller temperature gap than adults. Unlike adult fishes’ 27.5°C temperature range, spawners and embryos have an average range of 7.2°C to 8.4°C.

Why are spawners and embryos less tolerant to the warming ocean?

That’s because oxygen is more soluble in colder waters and less so in warmer ones. Meanwhile, fishes in the early life stage have a higher oxygen need than adult fishes.

Unfortunately, the ocean is warming too quickly for an evolutionary adaptation to occur. As a result, 60 percent of all fish species on the planet could go extinct by 2100.

It is worth making an effort to go for as little climate change as possible,” says Pörtner.

Read More: Mitigating Climate Change with Carbon Capture and Storage

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Sumbo Bello is a creative writer who enjoys creating data-driven content for news sites. In his spare time, he plays basketball and listens to Coldplay.

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