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scalloped

Starting in July, my phone started to ring… “Hi Dr. Lowe, I saw the strangest thing while out fishing off Catalina Island. I’m pretty sure I saw a hammerhead shark and didn’t think those occurred here.” 

That seems to be a common theme this summer and fall. There have been confirmed sightings of smoothed and scalloped hammerhead sharks, whale sharks, manta rays, blue marlin, wahoo, mahi, pods of sperm and pilot whales, and even schools of tuna along the southern California coastline and Channel Islands. So, this has raised a lot of questions about where are these animals coming from and why are they here now.

As strange as it might seem, this isn’t an unusual phenomenon. All of these charismatic megafauna that have caught people’s attention this summer are normally found in warmer southern waters off Baja. So, why are they here and now? The simple answer is they follow prey that are common in warmer waters, and this summer southern California waters got quite warm and have stayed warm.

There is no doubt this summer has been quite different than the last 10 or so; these conditions are more typical of what we experience during El Niño periods. Typically our summer water temperatures in southern California vary between 62 and 70° F; however, this summer I’ve heard of water as warm as 76° F off Catalina Island in August. Those who have lived in California for more than a few decades, may remember those big El Niño years (1982-83, 1997-98), when we were deluged in rain and were repeatedly hammered by big storms out of the south. While the presence of these large subtropical marine creatures is certainly indicative of an impending El Niño, NOAA has been very cautious in declaring whether the conditions we have been experiencing are really the results of a forming El Niño.

The warm water and the animals that follow those conditions are here, just like the El Niños of the past, so what make this year different? Where’s all our rain? The reason why the oceanographers have been hesitant to call this an El Niño year is that the warm water that extends out into the central Pacific during a strong El Niño has not developed the way we’ve seen in the past. So, what’s going on? Some climatologist believe this is the result of global climate change and that we we’re seeing a disruption in the normal El Niño formation pattern.

hammerhead

We do know that El Niños have been part of our normal global climate cycle and have regularly occurred over history, but this one seems different. While global ocean sensing technology (satellite imaging, ocean buoys) has grown leaps and bounds over the last 40 years, observation of the movements and distribution of marine animals in our oceans can also be important indicators of changing ocean conditions. While it seems like this summer’s conditions may have fooled us all, it certainly didn’t fool our marine visitors – they’re just here for the food. Maybe instead of being heralds of El Niño, they are actually harbingers of climate change. 

For more information:

http://www.elnino.noaa.gov/enso4.html

http://www.cpc.ncep.noaa.gov/products/analysis_monitoring/enso_advisory/ensodisc.html

http://www.gtopp.org/

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