Satellites have captured changes in marine life directly associated with a rapidly strengthening El Niño in the tropical Pacific Ocean.

The typical weather impacts of El Niño are widely known across the world – they include reduced rainfall in Australia, suppressed hurricane activity in the Atlantic, a weaker monsoon in India and heavier rain in some western areas of South America.

In addition to these atmospheric anomalies, El Niño events also cause large-scale changes to ocean currents and water temperatures across the Pacific Ocean, and these changes can have massive impacts on marine life.

Very strong El Niño getting stronger

El Niño developed in the middle of 2026 and has been strengthening rapidly in the last couple of months. By the middle of August, sea surface temperatures in the central tropical Pacific Ocean – a key monitoring region for El Niño – were more than 2.7°C above the 1991-2020 average. These are some of the highest anomalies on record for the central Pacific.

Computer models predict that this El Niño will continue to strengthen in the coming months and is likely to peak at record-breaking strength towards the end of 2026. Based on its forecast strength, El Niño will likely persist through the first few months of 2027.

The Bureau of Meteorology’s ACCESS-S model anticipates that the monthly relative temperature anomaly – which accounts for climate change – in the central tropical Pacific Ocean will reach around +3.6°C in November 2026. This would easily beat the previous record of +2.65 from November 1902, according to Bureau data dating back to 1900.

This very strong El Niño event will have far-reaching impacts on marine life across the Pacific, and some of these impacts are already starting to occur.

Marine food web responding to El Niño

NASA’s PACE satellite has detected suppressed phytoplankton abundance in the central Pacific Ocean in response to this year’s El Niño. The satellite detected a relative drop in chlorophyll-a concentrations – the pigment present in most phytoplankton – during June this year compared to June last year.

Phytoplankton abundance is directly linked to nutrient availability. When El Niño is underway, equatorial trade winds weaken or reverse over the tropical Pacific. This causes warm water to build near the surface of the central and eastern tropical Pacific, suppressing the upwelling of cooler, nutrient-rich water.

Image: Concentrations of chlorophyll-a in the equatorial Pacific Ocean in June 2025 (left) and June 2026 (right). The presence of El Niño in 2026 has caused a reduction in chlorophyll-a concentrations in parts of the Pacific Ocean. Source: NASA Earth Observatory / Michala Garrison.

Phytoplankton are important because they produce oxygen and feed other organisms. While microscopic, these tiny plant-like organisms play a critical at the foundation of marine food webs. For example, phytoplankton feed small marine animals called zooplankton, which feed larger fish, whales and other marine life.

Peru’s anchovy fishing operations – which produce around 20% of the world’s fishmeal and fish oil production – are also sensitive to El Niño. Past El Niño events have caused significant declines in fish numbers near Peru because of warm surface water and suppressed upwelling in the eastern tropical Pacific.

Fishing operations in Peru have been suspended in recent months due to this year’s developing El Niño. Earlier this month, the Peruvian Ministry of Production (PRODUCE) carried out operations to obtain information about the state of anchovy and other open-water resources near Peru.

According to reports, this assessment found that anchovy shows relatively good growth and reproductive activity in Peruvian waters, despite the developing El Niño. This information offers some hope that operations can resume sustainably, even as El Niño continues to strengthen.

Sea birds can also be impacted by disruptions to marine food webs driven by El Niño. Last month, there were reports of pelicans flocking to Peruvian ports to find food as fish stocks declined offshore.

Coral bleaching also has close links with El Niño’s ocean warmth. According to forecasts from NOAA’s National Weather Service, there is a 90% likelihood of coral bleaching across a broad area of the central and eastern tropical Pacific Ocean in the next 4 months. This region closely matches the warm water footprint of El Niño.

Image: Probability of coral bleaching in the next four months. Source: NOAA.

This El Niño event will continue to have far-reaching impacts across the world during the rest of 2026 and early in 2027.