What Harms Whales and Dolphins the Most


The consequences of climate change, according to a report by the Whale and Dolphin Conservation (WDC), are increasingly threatening whales and dolphins. The warming of the seas is having a dramatic impact on a variety of species, as stated in the report “Whales in Hot Water,” released on Friday during the UN Climate Conference (COP28) in Dubai.

According to the report, the habitats of whales and dolphins are changing so rapidly that species are competing with each other and, in some cases, engaging in conflicts. The rising temperatures are leading to an increase in algal blooms that release toxins. According to the WDC, these toxins are increasingly found in deceased whales and dolphins.

These poisons could potentially slow down the responsiveness of marine mammals, increasing the risk of collisions with ships.

According to the report, at least 343 baleen whales died in Chile in 2015; extremely high concentrations of the paralyzing toxins were detected in around two-thirds of the animals. “The sudden mass mortality is most likely due to an algal bloom,” writes the organization.

The animals are also increasingly moving into new and sometimes heavily used waters, not least increasing the risk of collisions with ships. According to the WDC, marine mammals can also become more susceptible to disease.

Almost two-thirds of disease outbreaks in whales and dolphins were recorded during periods of increased sea surface temperatures, which are likely to occur longer and more frequently with climate change. In some cases, there are fights between related species.

Increasing heat events have led to the migration of common dolphins to areas with Californian porpoises. Dolphins there increasingly attacked their smaller relatives, often with fatal consequences.

According to WDC, a problem is also the decline of krill as one of the main food sources for baleen whales. Industrial fishing and warming sea temperatures are decimating it.

In the Southern Ocean, where whales migrate during the polar summer, krill abundance has decreased by 30 percent since the 1980s. A decline of 16 to 19 percent is predicted for the Pacific and the Atlantic by 2100.

With the scarcity of food, marine mammals may store less fat and no longer have sufficient energy for their seasonal migrations. It has also been observed that many animals no longer migrate to warmer waters for mating. Result: fewer offspring.

The goal of the Paris Agreement to limit the global temperature rise to 1.5 degrees Celsius must be pursued, according to the organization. Effective protected areas should also be established, crucial for the animals: areas where they can feed, reproduce, and migrate.

A significant threat to whales and dolphins is also fishing gear. Governments and industries must prohibit destructive fishing practices. There should be fishing restrictions and alternative gear that reduces bycatch.