How El Nino Might Be Affecting Shark Behavior Near Oahu This Year
Shark Activity in Town Recently
Recently, there has been an increase in shark activity around Oahu, including high-profile attacks and sightings of different shark species. Waterman Mark Healy, known for his expertise in surfing and spearfishing, shared on Instagram that he has witnessed more aggressive shark behavior around Oahu in the past few months than ever before. He mentioned fish being taken from him by sharks for three consecutive days on different sides of the island, with species like tigers, sandbar sharks, and Galapagos sharks being involved, often on the larger end of the size range.
Mark Healy has proposed a theory that this heightened shark activity could be related to the forecasted El Niño event. He speculates that the coming El Niño might be a strong one, and there could be some validity to his theory. Shark migration patterns, feeding habits, and mating habits are known to be influenced by water temperature, and the El Niño/La Niña oscillation is defined by water temperature changes in the Pacific Ocean.
Currently, there is a transition from an historic triple-dip La Niña event (the first in 60 years), where surface temperatures in the Pacific were more than one degree colder than average for three consecutive years, to a strong El Niño pattern, characterized by surface water temperatures that are more than one degree warmer than average. This indicates a significant two-degree change in average surface water temperatures throughout the Pacific, which could potentially affect shark behavior and distribution.
It's important to note that the relationship between El Niño and shark activity is complex and not fully understood, and other factors may also be at play. Shark behavior is influenced by various ecological and environmental factors, and it's crucial to continue researching and monitoring shark populations to better understand their movements and behaviors. Additionally, it's essential to prioritize shark conservation and promote responsible human-shark interactions to ensure the conservation of these vital apex predators in marine ecosystems.
What is El Niño?
El Niño is a climate pattern characterized by warmer than normal sea surface temperatures in the central and eastern tropical Pacific Ocean. It is part of the El Niño-Southern Oscillation (ENSO) cycle, which also includes La Niña (cooler than normal sea surface temperatures) and ENSO-neutral (near-average sea surface temperatures) phases.
El Niño's Effects on Weather in Hawaii:
El Niño has a significant influence on weather patterns in Hawaii. During El Niño, the trade winds that typically blow from the east along the equator weaken, and sometimes even reverse to westerlies. This can cause changes in rainfall distribution, sea level pressure, and wind patterns, leading to various impacts:
Reduced Rainfall: El Niño tends to bring drier conditions to Hawaii during the normal wet season (November to April). Rainfall during the developing El Niño starts out wetter than normal from August to October but rapidly declines by November, sinking to well below average by February of the following year. The intensity of the dry conditions depends on the strength of the El Niño event, but widespread dryness across the Hawaiian Islands is typical. Rainfall usually returns to normal by July of the year following an El Niño event, but water managers should expect minor impacts on surface water availability and increased demand on groundwater resources during the dry period. (Source: National Oceanic and Atmospheric Administration - NOAA)
Increased Tropical Cyclone Activity: El Niño tends to increase the number of tropical cyclones (TC) in the eastern and central North Pacific regions, which can affect Hawaii during the TC season of El Niño years. This can result in an increased risk of tropical cyclones, including potential damage to infrastructure due to tropical cyclones, flooding, and erosion associated with high waves, requiring disaster managers to be prepared. (Source: Central Pacific Hurricane Center)
El Niño's Effects on Ocean Conditions in Hawaii:
El Niño also impacts ocean conditions in Hawaii, including sea levels, water temperatures, and marine life:
Sea Level Changes: During strong El Niño years, sea levels in Hawaii are near to slightly above normal. Exceptionally large swells associated with winter storms tracking north of Hawaii are common, which can affect coastal and ocean resource managers, recreation and tourism, and coastal resources. (Source: Pacific Islands Ocean Observing System)
Ocean Temperature Changes: El Niño causes ocean waters to warm substantially in the central and eastern Pacific at both the surface and subsurface. In Hawaii, warmer than normal ocean waters are commonly observed during strong El Niño events, which can affect fish populations and coral reefs. This can lead to an increase in fish populations and coral bleaching events, which may impact marine resource managers and those involved in agriculture. (Source: Hawaii Coral Reef Initiative Research Program)
Surf Predictions for Hawaii:
Surf conditions in Hawaii are also influenced by El Niño. During El Niño events, changes in wind patterns and ocean temperatures can affect surf conditions on both the south shore in summer and the north shore in winter.
Summer South Shore Surf: With weakened trade winds during El Niño, the south shore of Hawaii may experience smaller waves and less consistent surf during the summer season. However, other factors such as local weather patterns and storm activity can also impact surf conditions, so it's important to stay updated with the latest surf forecasts.