Marine life facing the wave of Namibia's oil boom

Namibia is receiving increasing global attention in light of recent oil and gas discoveries in our deep waters. Yet most Namibians don't know what oil and gas exploration and drilling entails and what that may mean for our marine life.

The Namibian Exclusive Economic Zone (EEZ) is part of the highly productive Benguela Current ecosystem. Our EEZ is home to at least 31 whale and dolphin species. The iconic bottlenose and Heaviside's dolphins are adored by coastal residents and tourists. In the deeper waters, Namibia hosts sperm whales, blue whales and fin whales, among others.

Besides the mammals, the EEZ supports a multitude of seabird species like albatrosses, shearwaters and petrels. Pelagic fish species including sunfish (Mola mola), sharks (e.g. blue and hammerhead sharks) and sea turtles (e.g. loggerhead and green turtles) are among the many iconic species that inhabit these waters.

Namibia's marine fishing industry and coastal tourism operations rely heavily on the diversity of life supported by the Benguela Current ecosystem. While other industries like oil and gas can be accommodated, Namibians need to know if regulations regarding exploration and drilling are fit for purpose and properly implemented. As a marine mammal observer who works on vessels and rigs, I will shed light on what happens during exploration, what measures are in place to limit the impacts on marine animals, and how these are being implemented.

How oil and gas is discovered offshore

During the exploration phase, oil and gas companies search for hydrocarbons: marine life that died and settled on the ocean floor thousands of years ago and is now buried deep in the ocean's sediment layers. Since drilling is expensive, they first need to map the geographic layers of the seabed using a process called seismic surveying. Once they locate promising quantities of hydrocarbons, they can decide whether or not to explore further using exploration wells.

Seismic surveys are based on the concept of echolocation – by blasting soundwaves at the ocean seabed and then measuring the echoes using the latest technology, one can create 3D images of the ocean floor. The soundwaves are produced by an array of huge airguns towed behind large vessels specifically designed for seismic exploration. The arrays used for 3D surveys can spread 2 km wide and up to 10 km behind the vessel!

The airgun array produces up to 260 decibels of low frequency sound pulses into the water column (jet engines produce 140-150 decibels during take-off) and up to 2000 psi of pressure. The full array of airguns is fired every 7-10 seconds 24/7 for four to six months, as the vessel moves slowly and methodically through the area that is being explored.

Hydrophone cables are towed alongside the airguns to detect the returning echoes. A team of geologists interpret the reflected sound waves and generate high resolution, 3D pictures of the seabed, which will reveal “pockets” or structures in the geological layers potentially containing hydrocarbons.

Seismic surveys in Namibian waters

Seismic surveys are not new. Exploration companies have been surveying Namibia's waters since the early 1970's. By now, most of Namibia's exclusive economic zone (EEZ) has undergone seismic surveying, which is divided into four offshore basins: Orange, Lüderitz, Walvis and Namibe. These basins are further divided into exploration blocks, which oil companies can only access after obtaining Petroleum Exploration Licenses (PELs).

The seismic data obtained from past surveys guide drilling companies on which prospective basin and associated PEL to focus on, thus maximising their discoveries. Companies will often do more seismic surveys after receiving a PEL, especially if previous surveys produced the less accurate 2D maps.

The recent discoveries in the Orange Basin of southern Namibia have resulted in many more exploration activities than before. A few years ago, observers like myself aboard an exploration vessel would go for months without seeing another seismic vessel or drilling rig. It is now more common to see several rigs and vessels in the same area.

How does seismic surveying affect marine animals?

Unsurprisingly, the constant noise and pressure being discharged into the ocean can affect a multitude of marine species residing in or migrating through Namibian waters. Fish may abandon their feeding areas and spawning grounds to avoid the survey area, change their shoaling behaviour, or adjust their migration routes. In severe cases, the airgun blasts can damage sensitive fish eggs and larvae. These changes can result in reduced catch rates in commercial fisheries over large areas and reduce the reproductive success of fish species. Seabirds can be displaced from important feeding areas, either because they are disturbed by seismic activity, or because their preferred prey species are avoiding the area.

Sound-sensitive species like marine mammals are arguably most affected by seismic surveys. Whales and dolphins use echolocation to “see” underwater and communicate with each other. The loud sound pulses overlap with the frequency ranges these mammals use, essentially drowning out their echolocation clicks and communication calls. This can lead to interrupted feeding when they fail to effectively locate their prey, and reduced breeding success if they cannot communicate with potential breeding partners.

Some species, like humpback whales, travel through Namibian waters when they migrate from their cold feeding waters in the Southern Ocean to their warm breeding waters off the coast of Gabon. They will often actively avoid seismic vessels or areas of high disturbance, like the crowded Orange Basin. For resident animals, the prolonged exposure to noise (up to 6 months for most seismic surveys) can cause high stress levels. Animals that are too close to the vessel when the arrays are blasting may experience temporary or permanent hearing loss.

How do Namibian regulations reduce these impacts?

Similar to mining and development projects on land, offshore exploration in Namibia (be it seismic surveys or drilling of wells) require an Environmental Clearance Certificate (ECC) prior to project mobilisation. Environmental Impact Assessments (EIAs) must be conducted to evaluate the potential risks to the marine environment, including recommendation measures to mitigate (prevent or reduce) any potential negative impacts the project activities could have on the surrounding environment.

While Namibia does not have its own local standardised regulations for protecting marine life during offshore exploration, we have adopted international best practice regulations from the United Kingdom's Joint Nature Conservation Committee, with some additional recommendations that apply to our local species.

Recommendations to minimise the risk of injury or disturbance to marine animals are included in the project Environmental Management Plan (EMP). First, survey periods should not overlap the periods of time when migratory species (like humpback whales) are most likely to be in Namibia's waters (from June to November).

Second, the airguns should be ramped-up gradually to their full production volume to reduce the risk of hearing loss or injury to animals within close range. The ramping up time allows animals to escape from the area immediately around the vessel.

Third, seismic shooting should be halted temporarily when species of concern are within a specified distance (typically 500 meters) from the active airguns. Mammal observers are stationed on parts of the vessel where there is maximum visibility and will use binoculars to detect these species during the day. During both day and night hours, we use acoustic monitoring methods to detect animals and order temporary halts in shooting when necessary.

Marine fauna observers are employed by independent contractors to monitor wildlife on the survey grounds and enforce these and other mitigation measures that are provided in each project's EMP. The data we collect and the reports we produce should be used to inform future EMPs in the same or neighbouring PEL exploration blocks.

While the regulations stated above are usually part of EMPs for exploration, this is not always the case. The pressure to explore the new discoveries in the Orange Basin is starting to push seismic surveys into the whale migration season, while some EMPs do not adhere to best practices. By law, marine observers can only enforce what the EMPs stipulate, so it is critical that these documents incorporate current biodiversity data and international best practices.

As the oil boom grows, Namibia must continue to enforce strict regulations to safeguard our marine wildlife and the wider Benguela ecosystem. This is not purely a conservation concern, since many livelihoods in the fisheries and tourism sectors also depend on marine life. Strong governance not only mitigates ecological risks but also enhances Namibia's reputation as a responsible energy producer committed to sustainable ocean management.