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Weathering the storm: the impact of El Niño on global fisheries

Earlier this month, the Bureau of Meteorology (BOM) formally declared an El Niño weather event following an eight year hiatus. El Niño is recurring climatic event which forms part of the El Niño Southern Oscillation; a climate phenomenon characterised by the periodic warming (El Niño) and cooling (La Niña) of sea surface temperatures in the central and eastern tropical Pacific Ocean. The changes caused by El Niño can wreak havoc on marine ecosystems and the fisheries which they support. In light of the recent announcement, this week’s blog post will explore the El Niño phenomenon and its broader implications for global fisheries productivity.

The Naming of El Niño The term ‘El Niño’ was coined by Peruvian fishermen during the 1600s. These fishermen were the first to notice periods of unusually warm water in the Pacific Ocean. Due to the event’s tendency to arrive around Christmas, it was named ‘El Niño de Navidad (Christ Child)’.

Understanding El Niño In order to grasp the El Niño phenomenon it is important to understand the ‘business as usual’ weather conditions that take place in its absence. Normally, strong trade winds blow from east to west across the tropical Pacific Ocean. These winds push warm surface waters towards the western Pacific, which borders Asia and Australia. At the same time, along the eastern Pacific (Ecuador, Peru and Chile), nutrient rich, cooler waters rise towards the surface. This process, otherwise referred to as upwelling, provides food for a wide variety of marine life, including most major fishes.

During an El Niño event, westward-blowing trade winds are weakened (or in rare cases, reversed). These changes lead to the accumulation of warm surface waters in the eastern tropical Pacific. In doing so, El Niño causes a thick layer of warm water to form which prevents normal upwelling from occurring. Simultaneously, it also produces widespread changes in climate, which vary by region:

El Niño's Impact on Fisheries

  1. Reduced productivity: The disruption of upwelling during El Niño events leads to declines in primary productivity. In doing so, it affects the availability of plankton and other food sources. This can have cascading effects across the entire ecosystem, ultimately affecting the abundance of fish populations.

  2. Shifting distributions: the changing sea surface temperatures associated with El Niño can cause fish populations to migrate in search of more suitable conditions. Fish that were once abundant in certain areas may move to cooler or deeper waters. In doing so, it can affect catch rates.

  3. Coral bleaching: the warming caused by El Niño events is often associated with mass episodes of coral bleaching. During a bleaching event, these essential fish habitats are compromised and in some cases, lost altogether. This can lead to rapid and widespread degradation of ecosystem services that depend on live coral cover, including fisheries catches.

In hot water: the impact of El Niño on the Peruvian anchovy fishery Peru is home to one of the world’s largest and most productive fisheries: the Peruvian anchovy. This small, oily fish is a crucial component of the marine food web, serving as a primary food source for an array of species. Historically, due to the impact of El Niño events, the Peruvian anchovy fishery has experienced significant fluctuations in abundance. Of note, was the collapse of the fishery in the early 1970s. This collapse was driven by a strong El Niño event which caused a significant reduction in phytoplankton: the primary food source for anchovies. The fishery’s ability to withstand such dramatic change (resiliency) was compromised due to prolonged periods of overfishing during the 1960s. As a result, annual catches plunged from 10 million tonnes in 1971 to just 4 million in 1972.

As we look to the future, it is likely that El Niño events will become more frequent and intense due to the impacts of climate change. In the face of such change, addressing practices which compromise the resilience of fisheries (e.g., overfishing, IUU fishing) is more important than ever. Without such, cases of fisheries collapse (such as the Peruvian anchovy) will become far too familiar. Blueshift’s team of experts specialises in providing tailored solutions to help fisheries navigate the complexities of climate change. With a deep understanding of marine ecosystems and sustainable practices, we offer comprehensive strategies to optimise your operations, reduce environmental impact, and ensure long-term resilience. If this is something you are interested in, please reach out to us via our LinkedIn or website:

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