Nicole Welle | July 6, 2020

A new study conducted by researchers at the Alfred Wegener Institute, Helmholtz Centre for Polar and Marine Research shows that rising water temperatures caused by climate change will negatively affect many fish species’ ability to breed.

Researchers found that fish are at a much higher risk than previously assumed. The study, which included 694 species of fish, showed that both embryos and adult fish that are ready to mate have a much lower tolerance for heat that adults outside the mating season and that that rising water temperatures could impact the reproduction of up to 60 percent of all freshwater and saltwater fish species, according to a Science Daily article.

Like many organisms, fish need to take in oxygen to produce energy, and their energy needs depend on the temperature of their surroundings. When the water is warmer, their need for energy rises and they need to take in more oxygen. Fish embryos do not have the ability to take in more oxygen as temperatures rise since they don’t have gills. Additionally, adults ready to mate produce egg and sperm cells and have an increased body mass, so their cardiovascular systems are already strained and struggle to handle any increased need for oxygen. This means that both of these groups cannot survive in warmer temperatures that require them to produce more energy.

If climate change continues unchecked, many species of fish will be forced to leave their traditional spawning areas. This could be disastrous for fish that do not have the ability to find cooler areas to reproduce due to the geographical restrictions of their habitat, and many fish populations are likely to decline.