EL NINO MAY SHIFT FISH STOCKS

El Nino, a natural climate phenomenon originating in the tropical Pacific Ocean, can influence weather patterns and marine ecosystems worldwide. Changes in sea temperatures and marine productivity can affect fish distribution, potentially altering traditional fishing grounds and the availability of familiar species.
Dr Saud bin Muslim al Jufaili, Associate Professor in the Department of Marine and Fisheries Science at Sultan Qaboos University’s College of Agricultural and Marine Sciences, said El Nino is characterised by an unusual rise in sea surface temperatures in the tropical Pacific, driven by complex interactions between the ocean, atmosphere, winds and ocean currents.
“El Nino is not simply a rise in sea temperature. It results from interactions between the ocean, atmosphere, winds and water movements,” he said.
The phenomenon does not occur every year or follow a fixed cycle. It develops at irregular intervals and may last several months or, in some cases, a year or longer.
Its effects vary by region. El Nino may contribute to higher temperatures and drought in some areas while bringing increased rainfall to others. It can also influence marine ecosystems by altering water temperatures and productivity, affecting the distribution of certain fish species.
Regarding fisheries, Al Jufaili said, 'Changing marine conditions can affect fish distribution, feeding, growth and reproduction. However, El Nino does not necessarily lead to a decline in fish stocks.'
“Some species may move to areas with more favourable conditions, while others may appear in locations where they were previously less common,” he said.
Such changes can be particularly noticeable to fishermen who depend on their knowledge of traditional fishing grounds. When familiar species become less abundant in their usual locations, fishermen may wonder where they have gone and whether they will return.
Al Jufaili explained that the absence of fish from a familiar fishing ground does not necessarily indicate a decline in their overall population. They may have moved elsewhere in response to changing water temperatures or other environmental conditions.
Prolonged periods of elevated sea temperatures can also place coral reefs under thermal stress, potentially causing coral bleaching. This occurs when corals lose the symbiotic algae that provide much of their colour and contribute to their energy supply.
Al Jufaili clarified that El Nino does not cause earthquakes or tsunamis. Rather, it is a climate and ocean phenomenon that can alter rainfall and temperature patterns and influence the likelihood of certain extreme weather events in parts of the world.
Scientists monitor El Nino using indicators such as sea surface and subsurface temperatures, wind patterns, atmospheric pressure, rainfall, sea levels and ocean circulation. Observations of marine ecosystems and fisheries also help researchers assess its potential effects.
For Oman, understanding El Nino provides a scientific basis for investigating possible changes in the Arabian Sea, marine ecosystems and fisheries. However, Al Jufaili cautioned against automatically attributing changes in fish catches or marine conditions to the phenomenon, as fisheries are influenced by multiple environmental factors.
He emphasised the importance of continued marine monitoring and scientific assessment to better understand natural ocean processes, support fishing communities and promote the sustainable management of Oman’s fisheries resources.