Who gains from saving nature
Ledger 1 : 33 — For each dollar financing nature-based solutions in 2023, about $33 financed activities harmful to nature. (UNEP)
Cases / Oil, gas and coal operations · Mauritania · 2018–2025

Greater Tortue Ahmeyim LNG project, the deep-water coral reef and BP's reef mitigation

Nature's voice · report
On my seabed along the future pipeline zone, the NCEA found live reef-building Lophelia corals in the ESIA's own baseline photographs; the ESIA had described them as solitary or fossil corals.
Did nature suffer? Yes. Harm is on record. Disputed
Recorded
What the record lacks: 4 none on record · 1 not disclosed · 1 insufficient · 1 not measured · 6 disputed · 1 unclear See the gaps
Accounts of the harm differ
Whether the artificial reef is mitigation or social investment
  • Government and regulators Senegal's fisheries ministry, as reported by Le Soleil: The reef is part of the GTA gas project's mitigation measures. Le Soleil (Cheikh Gora Diop)
  • Company or project BP communiqué, as reported by Ndarinfo: The reef falls under the GTA social investment programme. Ndarinfo
Adequacy of the biodiversity assessment in the ESIA
  • Company or project BP: The project was approved in 2018 by both governments and regulators following a thorough review process. Mongabay (E. Toto)
  • International bodies NCEA advisory (6 December 2018): The ESIA's environmental information is incomplete and/or has not been sufficiently used; baseline photographs show reef-building Lophelia, not solitary or fossil corals. Netherlands Commission for Environmental Assessment (NCEA)
  • Researchers Sandra Kloff, marine biologist and NCEA panel member: The biodiversity analysis was poorly done, with deep-sea species misidentified and currents not identified. Mongabay (E. Toto)
Environmental impact of the 2025 gas leak
  • Company or project BP: Low-rate subsea gas bubbles; the impact was expected to be negligible. Reuters via CNBC Africa
  • Government and regulators Mauritania's environment ministry: Conducting in-depth investigations to prevent any environmental impact. Reuters via CNBC Africa
  • Communities and civil society Greenpeace Africa (Dr Aliou Ba): BP showed utter disregard for marine life and coastal communities; BP should publish independent data on the leak. Greenpeace Africa
  • Communities and civil society A Saint-Louis artisanal fishers' association: Feared insidious pollution with possibly irreversible effects. Le360 Afrique / AFP

BP operates the Greater Tortue Ahmeyim LNG project on the Mauritania–Senegal maritime border, where the Netherlands Commission for Environmental Assessment found in 2018 that the environmental assessment was incomplete and that the seabed holds live reef-building Lophelia corals. A gas leak at one of four wells was found in February 2025, and a 3.2 billion FCFA artificial reef was announced as mitigation by Senegal's fisheries ministry.

3.2 bn FCFAArtificial reef off Saint-Louis, funded by BP, Kosmos Energy and Petrosen
Described by Senegal's fisheries ministry as part of the project's mitigation measures. Mongabay (2023) gave the Phase 1 cost as USD 4.5 billion.

Status As of December 2025: the artificial reef was immersed off Saint-Louis (BP, 17 December 2025); no revised ESIA is on record, and the 2025 leak was sealed on 12 March 2025.

What?
BP's Greater Tortue Ahmeyim LNG project was approved in 2018 after an NCEA review found the ESIA's environmental information incomplete and seabed photographs showing live reef-building Lophelia corals; a gas leak was found in February 2025 and an artificial reef was installed off Saint-Louis in 2025. Netherlands Commission for Environmental Assessment (NCEA)
Where?
Offshore on the Mauritania–Senegal maritime border: the gas field about 125 km from the coast and a nearshore hub 10–11 km off N'Diago (Mauritania) and Saint-Louis (Senegal); the coral reef system runs about 600 km from Cape Timiris to the Senegalese border (Mongabay); the artificial reef is about 4 km off Saint-Louis. Mongabay (E. Toto)
When?
ESIA 2018; NCEA advisory 6 December 2018; first gas 31 December 2024; leak found 19 February 2025 and sealed 12 March 2025; artificial reef immersed, announced 17 December 2025. Netherlands Commission for Environmental Assessment (NCEA)
Who?
Gained
  • BP, Kosmos Energy, Petrosen and SMH — Project partners; Kosmos and partners begin recognising revenue at the first cargo lifting Offshore Technology
Lost
None on record
Harmed
Why?
The NCEA recommended requiring the developers to update the ESIA before the authorisation decision; both governments approved drilling days later without changes to the ESIA (Mongabay). Senegal's fisheries ministry presented the artificial reef as part of the project's mitigation measures. Mongabay (E. Toto)
How?
The pipeline and floating production unit sit in a habitat of reef-building cold-water corals; the NCEA recommended studying reinjection of produced water; the leak came from a subsea well and was sealed with a device installed on 12 March 2025. Netherlands Commission for Environmental Assessment (NCEA)
6 of 6 questions answered from the record

What happened

The record, in order.

The Greater Tortue Ahmeyim (GTA) project is an offshore LNG development operated by BP with Kosmos Energy, Petrosen (Senegal) and SMH (Mauritania) on the Mauritania–Senegal maritime border. Mongabay gave the Phase 1 cost as USD 4.5 billion and the capacity as 2.5 million tonnes of LNG a year for about 20 years; Reuters (2025) gave 2.3 million tonnes a year. First gas reached the floating production unit on 31 December 2024 (Offshore Technology).

A 4,400-page environmental and social impact assessment (ESIA) was submitted to both governments in 2018. On 1 September 2018, at the request of Senegal's Direction de l'Environnement et des Établissements Classés (DEEC), the Netherlands Commission for Environmental Assessment (NCEA) began a review. Ten marine scientists sent an open letter on 12 November 2018. The NCEA's advisory of 6 December 2018 stated that the ESIA's environmental information is incomplete and/or has not been sufficiently used, and recommended requiring the developers to update the ESIA before deciding on authorisation of the project. Days later both governments approved drilling without changes to the ESIA (Mongabay).

On biodiversity the NCEA stated (translated from French) that the pipeline crosses habitats critical for fisheries resources and that the floating production unit also sits in this vulnerable environment. It described the habitat as made up of reef-building corals (Lophelia), extremely vulnerable to any physical disturbance of the seabed, and stated that seabed photographs from the ESIA baseline had been misinterpreted: they show reef-building Lophelia, not solitary or fossil corals as the ESIA states. It cited four scientific cruises by Ramos et al. (2017) that described live coral in the area, found the micro-contaminant baseline methods obsolete and not in line with OSPAR criteria, and stated that the zone likely holds "the only black corals of the slope" and had been identified as a candidate marine protected area. It also recommended a study of alternatives to discharging production water at sea, notably reinjection.

Senegal's national technical validation committee validated the ESIA on condition that its recommendations were taken into account. According to Mongabay (February 2023), BP agreed to review the ESIA after four years of petitioning by scientists; hazard modelling was awaiting funding, the original ESIA remained the official document, and the scientists' recommendations (reinjecting produced water, covering the pipeline with rock instead of trenching, a PAH baseline in Senegal) had not been adopted at the time of publication.

A gas leak was found on 19 February 2025 at one of four wells. BP and Mauritania's environment ministry announced it on 5 March 2025; BP said it had discovered low-rate subsea gas bubbles and expected the impact to be negligible. A sealing device was installed on 12 March 2025, after which the bubbles stopped visually, and BP said further tests, monitoring and visual inspections would continue. Greenpeace Africa asked BP to publish independent data on the leak. Separately, an artificial reef of 3.2 billion FCFA, funded by BP, Kosmos Energy and Petrosen, was shown at the Port of Dakar on 21–22 October 2025; BP announced on 17 December 2025 that it had been immersed about 4 km off Saint-Louis.

  1. 20184,400-page ESIA submitted to both governments; NCEA review starts 1 Sep at Senegal's DEEC request; ten marine scientists send an open letter 12 Nov; NCEA advisory 6 Dec; drilling approved days later without changes to the ESIA
  2. 2023February: BP agrees to review the ESIA after four years of petitioning by scientists; original ESIA still the official document
  3. 202431 Dec: first gas to the floating production unit
  4. 202519 Feb: gas leak found at one of four wells; 5 Mar: BP and Mauritania's environment ministry announce it; 12 Mar: sealing device installed; 21–22 Oct: reef modules shown at the Port of Dakar; 17 Dec: BP announces the reef is immersed

What was said

Claims, in the words of those who made them.

“are incomplete and/or have not been sufficiently used”

“before deciding on authorisation”

“the only black corals of the slope”

“We aim to contribute towards the conservation of the marine ecosystem in Mauritania and Senegal”

Marie Diop Toguyeni, BP head of communications for Mauritania and Senegal · February 2023 · Mongabay (E. Toto)

“we discovered low-rate subsea gas bubbles”

“conducting in-depth investigations to effectively manage the situation and prevent any environmental impact.”

“incidents of this kind often occur at the start of production”

“BP is once again demonstrating its utter disregard for marine life and coastal communities”

“these reefs will boost regeneration of fish stocks and preserve marine biodiversity”

Dr Fatou Diouf, Senegal's fisheries minister, on the artificial reef · October 2025 · translated from French · Le Soleil (Cheikh Gora Diop)

Where accounts differ

Each party's account, side by side, with its source. The record does not settle these points; it shows them.

Phase 1 LNG capacity
Press and investigations
Mongabay

2.5 million tonnes of LNG a year for about 20 years.

Mongabay (E. Toto)
Press and investigations
Reuters via CNBC Africa

2.3 million tonnes a year.

Reuters via CNBC Africa
Whether the artificial reef is mitigation or social investment
Government and regulators
Senegal's fisheries ministry, as reported by Le Soleil

The reef is part of the GTA gas project's mitigation measures.

Le Soleil (Cheikh Gora Diop)
Company or project
BP communiqué, as reported by Ndarinfo

The reef falls under the GTA social investment programme.

Ndarinfo
Adequacy of the biodiversity assessment in the ESIA
Company or project
BP

The project was approved in 2018 by both governments and regulators following a thorough review process.

Mongabay (E. Toto)
International bodies
NCEA advisory (6 December 2018)

The ESIA's environmental information is incomplete and/or has not been sufficiently used; baseline photographs show reef-building Lophelia, not solitary or fossil corals.

Netherlands Commission for Environmental Assessment (NCEA)
Researchers
Sandra Kloff, marine biologist and NCEA panel member

The biodiversity analysis was poorly done, with deep-sea species misidentified and currents not identified.

Mongabay (E. Toto)
Environmental impact of the 2025 gas leak
Company or project
BP

Low-rate subsea gas bubbles; the impact was expected to be negligible.

Reuters via CNBC Africa
Government and regulators
Mauritania's environment ministry

Conducting in-depth investigations to prevent any environmental impact.

Reuters via CNBC Africa
Communities and civil society
Greenpeace Africa (Dr Aliou Ba)

BP showed utter disregard for marine life and coastal communities; BP should publish independent data on the leak.

Greenpeace Africa
Communities and civil society
A Saint-Louis artisanal fishers' association

Feared insidious pollution with possibly irreversible effects.

Le360 Afrique / AFP
Chair of the NCEA review panel
International bodies
NCEA advisory (PDF)

Names Tanya van Gool as chair.

Netherlands Commission for Environmental Assessment (NCEA)
International bodies
NCEA project page

Lists Dano Roelvink as chair and van Gool as technical secretary.

Netherlands Commission for Environmental Assessment (NCEA)

How it looked

What was shown, beside what was recorded.

Shown

  • The project "was approved in 2018 by the governments and regulators of both Mauritania and Senegal, following a thorough review process".
    BP, quoted by Mongabay, February 2023 · Mongabay (E. Toto)
  • The artificial reef is part of the GTA project's mitigation measures.
    Senegal's fisheries ministry, as reported by Le Soleil, October 2025 · Le Soleil (Cheikh Gora Diop)
  • The artificial reef falls under the GTA "social investment" programme, funded to the tune of several million dollars; ten modular sets of cubes and pyramids designed for 99 years.
    BP communiqué, as reported by Ndarinfo, December 2025 · Ndarinfo
  • The impact of the 2025 leak was expected to be negligible.
    BP, as reported by Reuters via CNBC Africa, March 2025 · Reuters via CNBC Africa

Recorded

  • The NCEA's reading of the ESIA baseline photographs shows live reef-building Lophelia along the future pipeline zone; the ESIA had described them as solitary or fossil corals.
    Netherlands Commission for Environmental Assessment (NCEA)
  • As of February 2023 the original ESIA remained the official document and hazard modelling was awaiting funding.
    Mongabay (E. Toto)
  • A leak found on 19 February 2025 at one of four wells; bubbles stopped visually after sealing on 12 March 2025; BP said further tests, monitoring and visual inspections would continue.
    Le360 Afrique / AFP
  • Greenpeace Africa asked BP to publish independent data on the leak.
    Greenpeace Africa
  • The exact amount of the GTA social investment programme is not given in BP's communiqué.
    Ndarinfo

Who gained

Money that reached nature, beside money that stayed elsewhere.

Reached nature or the ground

Not published
Artificial reef off Saint-Louis (BP, Kosmos Energy, Petrosen)—
3.2 billion FCFA (Le Soleil). BP's communiqué says the programme is funded to the tune of several million dollars and gives no exact amount.

Gained elsewhere

Not totalled
Phase 1 project cost$4.5bn
Window: Phase 1
Mongabay, 2023.
Currency: USD · Window: Mixed — see each line. Figures cover different periods and are not compared as a ratio. * Estimate built from cited figures.

Responses on record

  • bp (February 2023; March 2025): Marie Diop Toguyeni said BP aims to contribute to conservation of the marine ecosystem in Mauritania and Senegal and that the project was approved in 2018 by both governments and regulators following a thorough review process. On the 2025 leak BP said it discovered low-rate subsea gas bubbles, expected the impact to be negligible and had a plan to stop the bubbles. · Reuters via CNBC Africa
  • mauritania-gov (5 March 2025): The environment ministry said it was conducting in-depth investigations to manage the situation and prevent any environmental impact; an oil ministry adviser said incidents of this kind often occur at the start of production. · Reuters via CNBC Africa
  • senegal-gov (October 2025): Fisheries minister Dr Fatou Diouf said the artificial reefs will boost regeneration of fish stocks and preserve marine biodiversity. · Le Soleil (Cheikh Gora Diop)

In court and with insurers

Every proceeding and every insurer decision on record.

Lawsuits and rulings

No court case on record. No court has ruled on this case.

Insurers

No insurer decision on record.

What nature saw

Outcomes measured on the ground, and nature's note.

Nature's report opens this page. Below: further outcomes measured on the ground.

Habitat on the pipeline route
Lophelia
Live reef-building corals, per the NCEA's reading of the ESIA photographs
Bottom-dwelling species on the reef
At least 150
Scientists cited by Mongabay
2025 leak
19 Feb–12 Mar
One of four wells; BP expected the impact to be negligible
Reef mitigation
3.2 bn FCFA
Artificial reef off Saint-Louis

What we don't know

Undisclosed, unproven, untried: recorded as data.
No court caseNo independent ecological evaluationKey earnings undisclosed

Nature

  • Disputed Whether the artificial reef is mitigation or social investment
  • Disputed Adequacy of the biodiversity assessment in the ESIA
  • Disputed Environmental impact of the 2025 gas leak

Money

  • None on record Artificial reef off Saint-Louis (BP, Kosmos Energy, Petrosen) — 3.2 billion FCFA (Le Soleil). BP's communiqué says the programme is funded to the tune of several million dollars and gives no exact amount.

Court

Accounts

Record

  • Not measured Not measured: the volume of gas released in the February–March 2025 leak; no independent measurement is on record, and BP's own assessment is that the impact was expected to be negligible.
  • Not disclosed Not disclosed: the exact amount of BP's GTA social investment programme; the communiqué says several million dollars.
  • Insufficient Insufficient: no revised ESIA had been published as of February 2023, and hazard modelling was awaiting funding.
  • None on record None on record: a biodiversity fund or offset for the cold-water reef itself; Mongabay (2023) mentions none.
  • None on record None on record: a court case or regulatory penalty.
  • Disputed Figures differ: Mongabay (2023) gives a Phase 1 cost of USD 4.5 billion, Offshore Technology gives USD 4.8 billion; Mongabay gives the reef system's length as 600 km, other press reports give 580 km.
  • Unclear Unclear: whether a revised ESIA or new hazard modelling was published between 2023 and 2026, and the status of Phase 2.

Did the harm stop?

The leak was visually stopped on 12 March 2025 after a sealing device was installed; BP said monitoring and inspections would continue. The NCEA's 2018 findings on the coral habitat are not recorded as resolved.

Who paid?

The coral habitat and its species along the pipeline route; no biodiversity offset for the reef is on record. BP, Kosmos Energy and Petrosen funded the 3.2 billion FCFA artificial reef off Saint-Louis.

Sources

Voices on record: — Company or project— Government and regulators— Courts✓ Press and investigations✓ Communities and civil society— Researchers✓ International bodies

Press and investigations

  4. 3.2 billion FCFA to bring Saint-Louis's fish back to life
    Le Soleil (Cheikh Gora Diop) · 2025-10-22
  6. First LNG at Greater Tortue Ahmeyim project
    Offshore Technology · 2025-02-10

Communities and civil society

International bodies

  2. NCEA project 7300 page
    Netherlands Commission for Environmental Assessment (NCEA) · 2026-10-19

Connected cases

Related matters, and cases linked to this one through the same organisations, with the role each played in both.
Terms used on this page

Carbon and conservation finance

Baseline
The projected scenario of what would have happened without a project, such as an expected rate of deforestation. Credits are issued for the difference between the baseline and what actually happened, so an inflated baseline produces more credits.
Offset
Using carbon credits to balance emissions released elsewhere, so that a buyer can claim lower or zero net emissions.

Law and courts

Negligence and gross negligence
Negligence is a failure to take reasonable care. Gross negligence is a serious, reckless failure; under US oil-spill law a finding of gross negligence raises the maximum penalty.
Plea
In a criminal case, the defendant's formal answer to a charge. A plea agreement settles a case with a guilty plea on agreed terms.

Insurance

Captive insurer, self-insurance
A company covering its own risks, either directly or through an insurance company it owns.
Similar cases
Protected area / relocation · Oil, gas and coal operations · Niger · 2012–2023
Termit and Tin Toumma National Nature Reserve: 2019 boundary change around CNPC oil blocks
Same type: Protected area / relocation, Oil, gas and coal operationsSame regionHarm to nature disputed
Water use · Oil, gas and coal operations · Protected area / relocation · Burning: incineration, open burning, flaring, fires · Iran · 2007–2026
Hoor al-Azim wetland, oil-field development and dikes in Khuzestan
Same type: Oil, gas and coal operations, Protected area / relocationHarm to nature disputed
Protected area / relocation · Tanzania · 1992–2026
Ngorongoro and Loliondo relocations
Same type: Protected area / relocationSame regionHarm to nature disputed
Carbon credits · Protected area / relocation · Kenya · 2012–2026
Northern Kenya Grasslands Carbon Project and the Isiolo court ruling
Same type: Protected area / relocationSame regionHarm to nature disputed
Protected area / relocation · Kenya · 2007–2024
World Bank and development bank accountability mechanisms: Embobut (Sengwer), Tata Mundra, Arun III, Jale, Cambodia
Same type: Protected area / relocationSame regionHarm to nature disputed
Tree planting · Protected area / relocation · Kenya · 1977–2023
Green Belt Movement and Karura Forest, Kenya
Same type: Protected area / relocationSame regionHarm to nature disputed