Is El Niño Behind California Great White Shark Sightings?

great white shark gansbaai There’s been a lot of Great White Shark activity in Southern California lately… sightings and video footage in Malibu, fly-fishing in San Diego, sightings in Northern Santa Barbara County, and more. To what can we attribute this sharp uptick in Great White Shark activity here in So Cal? How about El Niño?!

NOAA’s analysis of El Niño indicates that we can expect this cyclical phenomenon to appear this winter – “Synopsis: El Niño conditions will continue to develop and are expected to last through the Northern Hemisphere Winter 2009-2010.

During June 2009, conditions across the equatorial Pacific Ocean transitioned from ENSO-neutral to El Niño conditions. Sea surface temperature (SST) anomalies continued to increase… Subsurface oceanic heat content anomalies (average temperatures in the upper 300m of the ocean, Fig. 3) also increased as the thermocline continued to deepen. Consistent with the oceanic evolution, the low-level equatorial trade winds were weaker-than-average across much of the Pacific basin, and convection became increasingly suppressed over Indonesia. This coupling of the ocean and atmosphere indicates the development of El Niño conditions.”

Across the Atlantic, the world is watching and waiting… The Independent reports: “A new El Niño has begun. The sporadic Pacific Ocean warming, which can disrupt weather patterns across the world, is intensifying, say meteorologists. So, over the next few months, there may be increased drought in Africa, India and Australia, heavier rainfall in South America and increased extremes in Britain, of warm and cold. It may make 2010 one of the hottest years on record.”

Scientists present a number of theories for the increase in shark-human interactions: “Dr. George Burgess of Florida University, a shark expert who maintains the International Shark Attack file, states ‘As the population continues to rise, so does the number of people in the water for recreation. And as long as we have an increase in human hours in the water, we will have an increase in shark bites.’

Some experts suggest that an abundance of seals has attracted high numbers of sharks, while others believe that overfishing has hit their food chain. ‘I’m not saying it doesn’t happen, but it’s a convenient excuse,’ Burgess said. Another contributory factor to the location of shark attacks could be global warming and rising sea temperatures. ‘You’ll find that some species will begin to appear in places they didn’t in the past with some regularity,’ he said.”

NOAA has documented scientific evidence of El Niño’s impact on ocean life: “The more tropical pelagic thresher shark generally moves into California waters during periodic warm water episodes relating to El Nino conditions, being more abundant to the south off the Pacific coast of northern Mexico. When it occupies epipelagic habitat within the U.S. West Coast EEZ, it usually does not range north of southern California waters. Associated with sea surface temperatures 21EC and warmer.”

“There were also secondary problems caused by the 1982-’83 El Niño… Snake bites became more numerous in Montana, as the hot, dry weather drove mice from high elevations downward in search of food and water and the rattlesnakes followed. A rise in bubonic plague in New Mexico resulted from a cool, wet spring providing favorable conditions for flea-carrying rodents. An increase in shark attacks off the Oregon coast was due to unseasonably warm sea temperatures.”