New map shows areas at high risk of whaling vessel collisions – speed limits and route changes for ships could reduce tolls

A blue whale swims near a large ship near the Port of Colombo, Sri Lanka. Credit: Asha de Vos, CC BY-ND
Imagine you’re a blue whale swimming along the coast of California every spring. You are looking for krill in the Santa Barbara Channel. While this area is full of fish, kelp forests, seaweed beds, and other underwater life, it also vibrates from the noise of ship traffic. Suddenly, the noise gets louder.
You start to dive slowly and shallowly, but not in too much of a hurry. After all, our species has evolved for millions of years without this mysterious noise. So how do we know what to do when we hear that sound? One minute later, you are hit by a container ship and killed.
Your body slowly sinks to the ocean floor, where it feeds deep-sea life for decades, never to be seen again by humans. Indeed, your death will remain unnoticed. The ship barely registers the impact of impacting the largest animal species on Earth.
Collisions with ships are a serious threat to many large whale species. Although these events are difficult to study, scientists estimate that thousands of whales are killed by ships each year. In some areas, ship collisions are causing whale mortality rates that exceed what is considered sustainable after decades of whaling. Collisions with ships threaten some endangered species.
Research and experience show that simple measures can reduce these conflicts. For example, changing routes or slowing down ships to avoid areas important to whales. But to implement these interventions, scientists and policymakers need to know where whales are most at risk.
Mapping risks to whales
In a new study published in the journal Science, my colleagues and I mapped the global risk of ship strikes for four of Earth’s largest whales: blue, fin, humpback, and sperm whales. They found that within each species’ range, they travel thousands of times the distance that ships travel each year to the moon and back.
Our maps reveal the widespread risk of ship collisions in areas including the U.S. West Coast, the Mediterranean Sea, and the northern Indian Ocean. High levels of ship collisions have already been recorded in these areas.
We also found many other regions with similar levels of risk that have not been studied or recognized. These include several areas along the coastlines of South America and southern Africa, and areas around the Azores Islands off the coast of Portugal.
Most high-risk areas are unprotected
Whales have little protection from ship strikes around the world. We have identified hotspots of collision risk. This is an area in the top 1% of predicted risks worldwide, representing the most dangerous locations for each species.
Less than 7% of collision risk hotspots have measures in place to reduce collisions, such as limiting vessel speeds or requiring vessels to avoid certain areas. I understand. Exceptions include the west and east coasts of North America, where there is a higher level of ship collision control, and the Mediterranean Sea.
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Where such measures exist, they are often voluntary. Mandatory speed limits cover only 0.54% of blue whale collision risk hotspots, 0.27% of humpback whale collision hotspots, and do not include any fin or sperm whale hotspots.
For each species, the risk of ship collisions is higher within exclusive economic zones (areas within up to 200 nautical miles from the coastline where each country has exclusive jurisdiction over marine resources) than on the high seas. It turns out. This makes it easier to implement conservation and management measures in these areas.
Within their exclusive economic zones, countries can adopt voluntary shipping measures or propose mandatory changes through the International Maritime Organization, which regulates international shipping. There are many opportunities for countries to protect whales in their national waters.
But political boundaries mean nothing to whales, so the most effective approach may be for neighboring countries to work together to reduce the risk of ship strikes along the whales’ migration routes.
It was also found that the risk of ship collisions is high within existing marine protected areas (areas where countries have taken various measures to protect and manage marine life). Most of these marine reserves were established to protect marine life from fishing, but few place limits or regulations on shipping. If a marine protected area is at high risk of ship collisions, governments may add such measures to the protected area’s mandate.
Benefits of protecting whales
Protecting whales from ships will also benefit other species. Vessels can collide with many marine species, including seals, sea turtles, sharks, fish, penguins, and dolphins.
Maritime transportation is the largest source of underwater noise and poses a major threat to marine life. Underwater noise can disrupt feeding, interfere with communication, and cause stress for many species. Ships travel more quietly at lower speeds, so taking steps to reduce speed can reduce noise pollution and the risk of collisions.
Humans can also benefit from slowing down and rerouting ships. When ships travel slower, they are more fuel efficient and reduce greenhouse gas emissions. The shipping industry currently generates as much carbon dioxide emissions as aviation.
Slowing down ships also reduces emissions of harmful air pollutants that threaten human health in coastal areas and are estimated to contribute to hundreds of thousands of premature deaths each year. For example, in 2023, ships that voluntarily slowed down in California reduced greenhouse gas emissions by 45,000 tons, reduced nitrogen oxides by 1,250 tons, and cut the risk to whales by more than half.
By rerouting ships, we can make the ocean safer for local fishermen. In Sri Lanka, for example, heavy boat traffic along the coast overlaps with local fishermen and blue whale foraging. Several fishermen have died in recent years due to collisions with cargo ships. In response, some shipping companies have voluntarily shifted their routes further offshore to reduce the risk of collisions with humans and whales.
In our interconnected world, 90% of consumer goods are transported by ship on their way to market. Most of the items that consumers in wealthy countries purchase in their daily lives have come across the ocean at some point.
Our research shows that the risk of ship strikes is widespread, but in our view protecting whales from these strikes is a solvable problem. And by protecting whales, humans can also protect themselves.
Provided by The Conversation
This article is republished from The Conversation under a Creative Commons license. Read the original article.
Source: New map shows high-risk zones for whaler collisions—vessel speed limits and rerouting could reduce tolls (November 23, 2024) https://phys.org/news/2024 Retrieved November 23, 2024 from -11-high-zones-whale-ship-collisions.html
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