State of the Planet

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Blue Whale Population in Chile Threatened by Fishing Industry

The bays and fjords off the northern coast of Chilean Patagonia are a haven for the eastern South Pacific blue whale. In these productive waters, they forage for food and nurse their young. However, this valuable area for whales is also subject to heavy industrial fishing as well as smaller artisanal fisheries and aquaculture operations. Worldwide blue whale populations are currently categorized as endangered, as there are only about 25,000 blue whales alive today, less than one-tenth the number in the era before commercial whaling.

A study published in February found that whales in the northern Chilean Patagonia are forced to avoid many fishing boats every day, mainly from industrial operations. Concerned about the ecological threat caused by industrial fishing, the researchers — led by ecologist Rodrigo Hucke-Gaete at Universidad Austral de Chile — located areas of particular importance for conservation and regulation.

The researchers studied the factors that make the area an especially attractive habitat for whales. They also examined the effects of the interaction between vessels and whales, and the effects of noise pollution on the whale population. By tracking whale movements, Hucke-Gaete and his colleagues found that vessel traffic has a debilitating effect on the blue whales’ normal functioning.

Blue whales inhabiting the eastern South Pacific rely on and migrate to the productive marine ecosystems in the northern Chilean Patagonia during the summer months. There are specific ecological conditions in this region that make it an especially attractive habitat for the eastern South Pacific blue whale. Freshwater input from melting glaciers helps establish a bountiful food chain, beginning with upwelling of nutrients and organic matter that give the area extraordinarily high productivity. These nutrients support an abundance of krill, the small shrimp-like creatures which form the basis of blue whales’ diet.

blue whale
A blue whale. Members of the species can be up to 80 feet long. Source: MarcoPolo Rejsebureaus

Whales are not the only creatures drawn to the northern Chilean Patagonia; humans are attracted to these flourishing waters to harvest salmon in open-water fishing operations. Industrial fishing in this region dominates other areas of industry and overcrowds the waters. Eighty-nine percent of the ships in Chile’s Gulf of Ancud, a major part of North Patagonia, are fishing vessels, with the industrial vessels causing the bulk of the issues affecting whales. Along with industrial fishing operations, blue whales are forced to share the offshore waters with smaller artisanal fishing boats and aquaculture operations. Industrial fishing presents the greatest threat to blue whales, but artisanal fishing and salmon aquaculture are detrimental to whales’ ability to survive as well. Whales expend immense amounts of energy to avoid encounters with industrial vessels, smaller fishing boats, and the netted cages used in aquaculture operations. The whales also suffer from higher stress and greater competition for food resources.

As a part of their study to locate areas where vessels and whales are likely to encounter one another, Hucke-Gaete and his colleagues tagged whales, collecting data on their movement, and compared this information with data on shipping traffic. They also used species distribution models to predict how ecological and physiological factors affect whales’ movement in the area. The overlap of blue whale movement and vessel traffic helped researchers predict which areas were most prone to potential collisions between ships and whales. The researchers used the results of this study to call on the Chilean fishing industry to establish conservation and protection policies and self-regulate their operations.

map showing ships in the gulf of ancud
The Gulf of Ancud off Chilean Patagonia, important for nursing and feeding, is incredibly crowded with vessels. Source: MarineTraffic

Aside from establishing conservation areas in an effort to prevent collisions between whales and vessels, another major opportunity for supporting blue whale populations in Northern Patagonia is by regulating noise pollution from boats. Much as traffic noise and sirens can prevent two people who meet on a busy street from hearing each other, noise from boats impedes communication between whales. Marine animals rely on vocalizations to greet each other, breed, and navigate. Noise pollution from boats is damaging to the blue whale population by causing communications issues. 

In an unfortunate coincidence, the frequency that fishing boats in this region use to send signals to each other is the same as the one that whales produce in their vocalizations. In the absence of noise pollution, whales are able to communicate with each other at distances of thousands of miles. Noise produced by boats is also able to travel great distances, essentially cutting the line of communication that whales rely on to manage familial connections as well as coordinate great migrations to and from breeding and feeding grounds, which are crucial to the continuation of their populations.

Carlos M. Duarte, a prominent marine ecologist at King Abdullah University of Science and Technology in Saudi Arabia studying underwater noise pollution, found in a separate study that noise pollution coming from boats induces behavioral changes that impede whales’ ability to survive. Persistent ambient background noise causes intense stress for blue whales, interfering with their typical feeding behavior and pushes them from the krill-rich water they rely on. 

From 1950 to 2000, prompted by an expansion in the fishing industry, boat traffic in Northern Patagonia doubled, which led to an approximate increase in noise pollution of three decibels every decade. Three decibels every decade is equivalent to an astounding twofold increase in the volume of noise every ten years, dramatically increasing the intensity of the communication and behavioral issues facing whales in the region.

Scientists have speculated that climate change, combined with the associated ocean acidification and pollution, pose the greatest threat at present to marine mammals, but that persistent ambient noise might be the factor that could push the eastern South Pacific blue whale from endangered to extinct in the northern Chilean Patagonia.

There are feasible measures that can be taken to reduce noise pollution and curtail its effects on blue whale communication and behavior. Duarte and his team have proposed several solutions. Some of these solutions include quieting ships by lifting the engine off the floor of the vessel, mandating the use of propellers designed specifically to minimize the production of small bubbles, which make a loud sound when they pop, and regulating the speed that ships are able to come to port at. 

Duarte noted that during the coronavirus pandemic, as a result of the slowdown of industry, there was a 20 percent reduction in human-caused noise pollution in the ocean. One of the reduction’s effects was that whales were spotted in areas they had not been seen in for decades. 

“If we look at climate change and plastic pollution, it’s a long and painful path to recovery. But, the moment we turn the volume down, the response of marine life is instantaneous and amazing,” Duarte told the BBC. Noise pollution is much more easily regulated than other human activities, and its limitation has tremendous, rapidly appearing positive effects on wildlife.

As glacial melt continues, drawing more fishing vessels to Northern Patagonia, blue whales will pay the price if regulations are not implemented. Setting aside priority areas for conservation and enforcing noise pollution policies would go a long way toward allowing blue whale populations and industrial fishing enterprises to coexist and flourish.

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2 years ago

PLEASE look after the blue whales! I think you are privileged to have such fantastic creatures living near you