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What Seismic Blasting Does to Marine Animals

Seismic blasting for oil and gas has profound, far-reaching impacts on the health and behavior of marine animals across the world’s oceans.

By Medha deb

Created on Sep 27, 2025

Seismic blasting for oil and gas has profound, far-reaching impacts on the health and behavior of marine animals across the world’s oceans.

Seismic blasting is a widespread technique used by oil and gas companies to locate underwater fossil fuel reserves. Although essential for the energy industry’s exploration processes, these powerful underwater explosions have significant, often devastating consequences for marine life. This article explores how seismic blasting works, the ways sound travels in the ocean, and the ripple effects these blasts have on everything from the tiniest zooplankton to the largest whales.

Understanding Seismic Blasting

Seismic blasting, also known as seismic surveying, is a process that involves firing extremely loud airguns underwater. These airguns generate blasts of sound that penetrate the seafloor, reflecting off different layers of rock and sediment. The returning echoes are recorded by arrays of sensors, providing a map of what lies beneath the ocean floor. Oil and gas companies depend on this technology to pinpoint potential drilling sites.

The blasts can reach sound levels of up to 250 decibels (dB), vastly louder than a jet engine at takeoff.
During a survey, airguns can fire every 10 seconds, 24 hours a day, for weeks or months.
This repetitive noise can travel vast distances—sometimes hundreds or thousands of kilometers through ocean waters.

How Sound Travels in the Ocean

Sound moves differently in water than it does in air. Water is denser and a better conductor of vibrations, enabling sound waves to travel further and faster underwater than through the atmosphere. This physical property increases the ecological footprint of seismic noise dramatically.

Low-frequency sounds (like those from seismic airguns) can travel up to thousands of kilometers.
Marine animals rely on sound for navigation, communication, finding food, and avoiding predators—which makes them acutely vulnerable to disruptions.

The Ocean as a World of Sound

For many marine creatures, particularly those in the deep sea, vision is nearly useless. Sound, however, penetrates darkness and travels long distances. Marine animals have evolved to use sound as their primary sense for:

Communication: Whales, dolphins, and some fish communicate using complex sound signals.
Navigation: Species like whales and seals depend on echolocation to find their way and hunt prey.
Detecting Danger: Sudden noises or disturbances in the soundscape can signal potential threats or changes in the environment.

This fundamental dependence intensifies the risks posed by unnatural, extreme noise sources like seismic blasts.

What Seismic Surveys Sound Like to Marine Life

For a human, seismic blasting would be akin to a deafening explosion going off every few seconds, day and night. Underwater, the effect is even more powerful, given the strength and reach of the sound waves. Even animals not in the immediate blast zone experience repeated, disorienting noise that can mask natural sounds and communication.

The sound is not a single event—it’s a relentless barrage, with intervals often as short as 10 seconds between blasts.
The noise overlaps with the frequency range used by many marine animals for essential life functions.
Seismic blasts can be heard at distances of over 1,000 kilometers from the source, exposing vast swaths of the ocean to pollution.

Direct and Indirect Impacts on Marine Life

Research has made it clear: seismic blasting is not just an annoyance for ocean creatures. Its effects can be lethal, physically damaging, or deeply disruptive in behavior and physiology. A single blast can kill or injure organisms near the blast site, and repeated blasting over time can disrupt entire ecosystems.

Immediate effects: Death, physical trauma, and severe injuries to internal organs for those nearest the blast.
Long-term and indirect effects: Hearing loss, stress responses, behavioral changes, and displacement from critical habitats.

Table: Primary Effects of Seismic Blasting on Key Marine Groups

Group	Physical Effects	Behavioral Effects	Ecological Risks
Whales and Dolphins	Hearing loss, internal injuries	Avoidance, disrupted communication	Abandonment of feeding/breeding areas
Fish	Ear damage, reduced larval survival	Altered schooling, avoidance	Reduced catch rates, population declines
Zooplankton	High mortality, population collapse	Unknown (limited mobility)	Food-web disruption
Invertebrates (squid, crabs, etc.)	Tissue trauma, stress, organ damage	Alarm/startle responses	Mass strandings, reproductive harm

How Seismic Blasting Affects Different Marine Animals

Zooplankton: The Smallest Victims with the Biggest Consequences

Zooplankton are tiny, often microscopic creatures that form the base of the marine food chain. They include krill, copepods, and the larvae of much larger animals like crabs and fish. Despite their small size, zooplankton are highly sensitive to sound, and their demise has cascading effects throughout the ecosystem.

Studies show that seismic blasts can kill or injure zooplankton more than a kilometer away from the source.
Population collapses have been observed after blasts, potentially reducing food availability for fish, whales, and other species higher up the chain.
Mortalities in zooplankton larvae can affect recruitment into adult populations for many ocean animals.

Fish: Physical Injuries and Mass Disruptions

Fish are vulnerable to seismic sounds both as adults and in their early life stages (eggs, larvae).

Adult fish display ear injuries, internal trauma, reduced reproductive success, and changes in hormone levels after exposure to seismic noise.
Behavioral changes include dropping to deeper depths and fleeing from traditional breeding or feeding grounds.
Catch rates for commercially important species like cod, herring, and haddock have plummeted by up to 80% following seismic surveys, lasting for days and across broad areas.
Sound exposure causes decreased egg viability, higher embryonic mortality, and stunted larval growth in some species.

Whales, Dolphins, and Marine Mammals: Disrupted Communication and Trauma

Marine mammals—including whales, dolphins, and seals—are especially at risk because they are so dependent on sound for communication and survival. Many of these animals use echolocation or long-distance calls to navigate the vast ocean.

Hearing loss: Seismic noise can cause both temporary and permanent hearing damage, making it harder for mammals to communicate, navigate, or find food.
Stress and trauma: Intense exposure leads to increased stress hormone levels and, in extreme cases, physical trauma or internal injury.
Behavioral responses: Whales and dolphins have been observed fleeing from their habitats, abandoning calves, or suspending feeding and breeding in affected areas.
Population threats: For critically endangered species like the North Atlantic right whale, even small disruptions can be catastrophic at the population level.

Invertebrates: Often Overlooked but Deeply Affected

Invertebrates—such as squid, crabs, and shellfish—are also heavily impacted by seismic activity.

Squid: Exposed to seismic blasts, they display alarm and escape responses, sometimes ejecting ink and swimming rapidly away. Studies have documented mass strandings of giant squid associated with seismic testing, with animals showing extensive internal and organ damage.
Crabs and Shellfish: Seismic noise exposure can bruise ovaries, damage delicate sensory organs (statocysts), and lead to increased stress or even reduced catches for crab and mollusk fisheries.
Physiological markers of stress (like elevated hormones) have been documented in bivalves and gastropods exposed to seismic noise.

Sea Turtles: Uncertain but Concerning Risks

Evidence is emerging that sea turtles might be vulnerable to seismic blasting, too. While less is known about their specific physiological responses, turtles depend on the acoustic landscape for navigation—especially during long migrations across open ocean. Sudden, sustained sound pollution could threaten their ability to find nesting or feeding sites, and may contribute to strandings or changes in behavior.

Behavioral and Ecosystem-Level Effects

Seismic blasting doesn’t just hurt individual animals—it disturbs the balance of entire marine ecosystems.

Displacement of sensitive species from traditional feeding/breeding grounds can impact population sizes and reproductive success.
Reduction in zooplankton and fish numbers ripples up the food web to affect predators, including marine mammals and large carnivorous fish.
Disrupted communication and social structures, particularly in whales, can last longer than the duration of the blasts themselves.
Chronic noise pollution may cause abandonment of entire regions by some species.

Scientific Evidence and Growing Concern

Researchers from around the world are raising red flags about the risks associated with seismic blasting. Multiple controlled studies and independent observations have confirmed the physical, behavioral, and ecosystem effects described above.

Direct mortality and injury to zooplankton have been measured up to 1.2 kilometers from a single airgun firing.
Fish ear trauma, loss of schooling behavior, and significant drops in catch rates are well-documented.
Strandings and severe internal injuries in squid and other invertebrates have been reported coinciding with seismic survey activity.
International conservation bodies and scientific organizations have called for stricter regulation and further study, especially where vulnerable or endangered populations may be at risk.

Mitigation and Regulation

Some governments and regulatory agencies have imposed controls intended to reduce the impact of seismic surveys, such as:

Seasonal restrictions to avoid sensitive breeding or migration periods.
Exclusion zones to limit survey proximity to known critical habitats.
Real-time acoustic monitoring to detect and avoid nearby marine mammals.
Experimental alternative technologies (e.g., using marine vibrators rather than airguns) to reduce harmful sound emissions.

However, enforcement, data collection, and international cooperation remain uneven, and many experts argue that current measures are inadequate for fully protecting marine life.

Why Seismic Blasting Continues

The continued expansion of oil and gas exploration, especially in previously untouched ocean areas, drives an increase in seismic survey activity. Economic incentives are significant, and the technique remains critical for energy companies seeking new fossil fuel reserves. Despite its environmental drawbacks, seismic blasting is still widely used, and replacement technologies are not yet standard practice.

Frequently Asked Questions (FAQs)

Q: What is seismic blasting?

A: Seismic blasting is a process used in offshore oil and gas exploration, using powerful underwater airgun blasts to map the seafloor and detect fossil fuel reservoirs.

Q: How does seismic blasting harm marine animals?

A: The intense, repetitive noise can kill or injure animals close to the source and cause hearing loss, behavioral disruptions, and chronic stress in those farther away. This includes everything from zooplankton to whales.

Q: Are any animals more affected than others?

A: Animals that rely heavily on sound—such as whales, dolphins, and many fish—are especially vulnerable. Static or slow moving animals, like zooplankton and shellfish, are at risk of direct mortality because they cannot easily escape the blast zone.

Q: How far does the impact of seismic blasting reach?

A: The sound from seismic blasts can travel hundreds or even thousands of kilometers through ocean water, impacting animals and ecosystems far beyond the immediate vicinity of the survey.

Q: What can be done to reduce the impact?

A: Stricter regulations on timing and locations of surveys, development of quieter technologies, and increased research on cumulative effects can reduce the impact on marine life.

Conclusion: Listening to the Ocean’s Warnings

Seismic blasting delivers a deafening blow to the rich diversity of marine life, threatening creatures at every level of the food web. As scientific understanding grows, so too does the call for urgent regulatory action, international cooperation, and real investment in less harmful alternatives. Protecting the world’s oceans requires us to listen—to the scientists, to the warnings from nature, and to the voices of marine animals themselves, whose survival depends on an unpolluted world of sound.

References

Author

medha deb

Medha Deb is an editor with a master's degree in Applied Linguistics from the University of Hyderabad. She believes that her qualification has helped her develop a deep understanding of language and its application in various contexts.

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