Ocean temperatures off San Diego and along much of the West Coast are unusually warm — approximately 5 to 7 degrees above average. La Jolla's water temperature, for example, is 73 degrees; the average is 68.
The warm water is a result, in part, to the gripping high-pressure ridges that hovered over the region the past two winters.
“And that ridge of high pressure ended up causing a lack of the kind of storms passing through the gulf of Alaska that would typically cool the ocean surface,” said Nathan Mantua, research scientist and leader of the landscape ecology team with NOAA’s Southwest Fisheries Science Center.
The warmth is also due to very weak wind patterns. The lack of wind reduced coastal upwelling — when surface water is swept off shore and replaced by cold, nutrient-rich water from deep below the surface, Mantua explained.
Warm water favors small, nutritionally low plankton species, causing a big impact on the marine food web — from microorganisms to large mammals.
Mantua said the warm water is also changing fish communities.
“Game fish that people typically travel to Baja to fish for this time of year are now within reach of San Diego and ports around Los Angeles,” Mantua said, “because this warm water habitat is now much further north and in shore than it typically is.”
The warm water isn’t expected to cool anytime soon, Mantua said.
“This time of year we get into the weakest winds of the year, just before winter comes,” Mantua said. “So unless we have very unusual weather patterns, the warm water is going to stay with us. It might get warmer still.”
The warm water patches don’t appear to be related to El Niño, Mantua said.
"If we get El Niño, it would likely strengthen the situation we find ourselves in now, and it wouldn’t just warm the surface waters — the El Niño favors wind and current patterns that warm a much thicker layer of the upper ocean," Mantua said."
