What is the impact of shipping on cetaceans?

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Group of dolphins in the sea

The shipping industry is often cited as one of the most polluting economic sectors, due to its significant greenhouse gas (GHG) emissions that contribute to global climate change. However, air pollution is not the only issue. Noise and water pollution are increasingly being recognized as significant topics, with adverse effects on marine wildlife, particularly cetaceans. This article sheds light on the various ways that pollution caused by merchant ships can impact the health of marine mammals, and even threaten the survival of certain species. By examining these impacts, we can gain a greater understanding of the need for more sustainable and responsible practices in the shipping industry to protect the marine environment and its inhabitants.

What is the impact of pollution from ships on cetaceans?

Cetaceans, which include blue whales, sperm whales, humpback whales, dolphins, and porpoises, are a family of marine mammals and vital members of the marine ecosystem. They play a crucial role in maintaining the balance and sustainability of the ocean food chain by preventing the overpopulation of certain species. Moreover, these creatures significantly contribute to removing harmful carbon dioxide emissions from the atmosphere. Interestingly, whale excrement contains essential nutrients that promote the growth of phytoplankton, which is responsible for absorbing up to 10 billion tons of CO2 per year. Therefore, the presence of whales in the ocean is vital for the well-being of our planet.

Unfortunately, several studies have shown that pollution has a devastating effect on cetaceans, contributing to the decline of their populations. Yet, shipping is a significant source of various types of pollution for our oceans.

How does underwater noise pollution affect cetaceans?

Listening is a crucial aspect of cetacean life, as they rely on sound for hunting, feeding, navigation, rest, communication, reproduction, and travel along their standard migration paths. Human-induced disturbances, particularly underwater noise from ships’ propellers and engines, can interfere with these marine mammals’ ability to transmit and receive acoustic information in their daily activities and change their normal behavior. In the long run, such disruptions can have serious consequences, such as injuries, stress, growth, reproductive issues, or even death.

Baleen whales are especially vulnerable to the effects of shipping noise because they hear at lower frequencies. In contrast, toothed whales, including narwhals, dolphins, and porpoises, hear at high frequencies and use echolocation or biosonar for hunting. Consequently, ship noise can have a more significant impact on baleen whale populations.

How does water pollution impact cetaceans?

Perhaps one of the biggest threats facing cetaceans today is plastic waste. This harmful material is often referred to as the “deadliest predator in the sea.” The tragic consequences of plastic pollution are numerous, and many ocean mammals die when plastic blocks their breathing passages and stomachs or become entangled in abandoned fishing gear.

Additionally, dumping of oil spills, sewage, human waste, and harmful chemicals from ships and land-based activities directly into the water result in a variety of health issues, such as skin irritation, respiratory problems, reduced fertility, higher calf mortality, weakened immune systems, cancer, and other diseases. Cetaceans are also at risk of ingesting contaminated food sources. As these animals consume fish and other organisms that have absorbed pollutants, they may accumulate toxic substances.

But the danger does not stop there. Discharge of waste destroys their natural habitats, including coral reefs and marine flora, which are essential for the survival of many marine species.

Lastly, water pollution might affect the cetaceans’ chemoreception, which combined smell and taste, and is believed to be a critical sensory mechanism for cetaceans. Experts suggest that some species rely on their sense of smell or taste receptors on their tongues to detect the presence of prey or changes in the water’s salinity to navigate.

How do ship strikes endanger cetaceans?

A study conducted by the international sustainability program “Friend of the Sea” has revealed that around 20,000 whales are killed each year due to collisions with vessels’ hulls and propellers. The risk is higher for large tonnage ships and in areas with heavy shipping traffic. In busy shipping lanes, cetaceans become accustomed to the flow of vessels and may be less responsive when a ship approaches, increasing the likelihood of a strike. Unfortunately, most cetaceans do not survive ship strikes or may suffer serious injuries, which can vary depending on the size and speed of the vessel involved. For example, approximately 1,000 whale strikes occur annually off the coast of Sri Lanka.

Shipping lines are taking specific measures in order to help protect whales and other cetaceans, in accordance with guidance from the International Maritime Organization (IMO) and other experts in the field of marine animal welfare, such as the World Wildlife Fund (WWF), the International Fund for Animal Welfare (IFAW), as well as the international whaling commission.


  • Vessel speed reduction


For example, in California, the shipping industry is participating in a voluntary Vessel Speed Reduction (VSR) program in specific areas, upon requests from NOAA and the U.S. Coast Guard. The aim, in these very busy waters for large commercial vessels, is to drop the risk of ship strikes on whales within and near the local national marine sanctuaries (Greater Farallones, Cordell Bank, Monterey Bay, and the Channel Islands).

Steaming at slower speeds and drop of biofouling of its vessels’ hulls and propellers also contributes to underwater noise reduction. This is because a smoother movement of these components creates fewer bubbles and less cavitation, which in turn reduces noise.


  • Route changing


Stolt Tankers is one of the shipping lines that have taken significant steps to lower the likelihood of ship strikes and physical injuries to the whale population. As a matter of fact, a part of its fleet regularly crosses areas around the globe where cetaceans live and feed (northwest of the Mediterranean Sea, South of Sri Lanka, waters around Vancouver Island, and the east coast of the US). Going forward, apart from reducing their sailing speed from 12.5 to 10 knots, its ships will modify their routes in order to avoid the current traffic lanes frequented by endangered blue whales and other cetaceans.


  • Establishment of an extensive global database of marine protected areas across the world’s oceans by the Marine Protection Atlas (MPAtlas)


This tool is vital for researchers, policymakers, and conservationists within the frame of safeguarding the health of our oceans and the countless species that call them home.

On top of threatening the survival of the cetaceans, this has far-reaching consequences on the overall health and well-being of marine life.

Picture of the ocean taken underwater

What are the measures taken by the shipping industry to mitigate its impact on cetaceans?

In light of these threats to the marine environment, there is clearly an urgent need for raising awareness of these issues and innovative practices. The shipping industry stakeholders are aware of their role in supporting the United Nations Sustainable Development Goal pertaining to the protection of life below water.

Preserving whale populations is key to fighting against climate change. According to researchers from the University of Southeast Alaska, “the entire body biomass of a whale is largely composed of carbon”. Scientists consider them as one of the largest living “carbon reservoirs”. Because of their size and longevity, whales have the potential to store huge volumes of carbon dioxide in the ocean, which is one of the greenhouse gases responsible for global warming. Therefore, the recovery of whale populations can have a great impact on the carbon cycle and should lead to multiple benefits in fighting against biodiversity and climate crises.

In recent years, led by the International Maritime Organization (IMO), they have demonstrated a commitment to reduce the impact of their activities on the marine ecosystem, particularly with regard to pollution from ships.

As a result, regulations have been constantly reinforced to ensure that ships operate in a manner that minimizes their ecological effects, under the close supervision of the Marine environment protection committee (MEPC).

Furthermore, many initiatives have been launched to promote greater sustainability in the maritime industry. These initiatives commonly involve measures such as:

  • the implementation of new ship designs,
  • the use of alternative fuels,
  • the adoption of energy-efficient devices and processes,
  • improved waste management, and the incorporation of new technologies such as wind-assisted propulsion, solar power, and electric propulsion.

These efforts demonstrate the industry’s commitment to reducing its environmental impact and promoting a more sustainable future for marine life.

Digital technologies have become an invaluable asset to stakeholders in the maritime industry as they work to achieve more sustainable, green shipping practices. Sinay is a leader in providing innovative tools and data to all actors in the sea transportation sector and related businesses. Its comprehensive range of modules, APIs, metocean analytics, and technical support enables companies to assess their environmental impact, monitor and predict pollution, increase operational efficiency, and comply with regulations in force. Its environmental modules as regard water quality, underwater acoustic impact, and sea-life impact.

group of sea lions resting on a platform


At a local level, official bodies like the United States National Oceanic and Atmospheric Administration (NOAA) provide access to global environmental data from satellites. This information is critical to understanding the state of our oceans and for monitoring the health of cetacean populations.

In addition to official sources, online academic databases such as Google Scholar are a rich source of information for gaining a deeper understanding of the complex ways these endangered species perceive their environment. By staying up-to-date with the latest research, we can make more informed decisions in order to protect these magnificent creatures and their habitats.

All these actions enable the shipping industry actors to preserve oceans, as well as their resources, on which the marine species rely. By doing so, they ensure the long-term health and survival of cetaceans and biodiversity as a whole.

Frequently Asked Questions About Cetaceans and the Shipping Industry

Shipping activities can generate underwater noise that can interfere with cetaceans’ communication, feeding, and breeding.

Noise pollution can also mask sounds that cetaceans use to navigate, locate prey, and communicate with each other.

In some cases, this can lead to physical injury or even death, particularly for species that rely on echolocation to find their way around. 

Several measures are in place to prevent collisions between ships and whales, including speed limits, vessel rerouting, and lookouts.

For example, some shipping lanes have speed limits to reduce the risk of collisions, while some areas have been designated as whale corridors that ships are required to avoid. Additionally, some ships use specialized techniques such as sonar or infrared cameras to detect whales in their path. 

Shipping activities can release pollutants such as oil, chemicals, and plastics into the ocean, which can accumulate in the bodies of cetaceans and cause health problems.

It can lead to respiratory and digestive problems, while exposure to plastic debris can cause entanglement, ingestion, or suffocation. Chemical contaminants such as heavy metals, pesticides, and flame retardants can also accumulate in cetaceans’ tissues and lead to reproductive, immunological, and neurological disorders.

Reducing vessel speeds can reduce the noise level and the risk of collisions. Avoiding sensitive areas, such as breeding or feeding grounds, can also minimize disturbance to cetaceans.

Using alternative fuels, such as biofuels or LNG, can reduce emissions and prevent chemical contamination.

Supporting conservation efforts, such as marine protected areas or whale monitoring programs, can also help protect cetaceans from the impacts of shipping.

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