Scientists monitoring new marine heat wave off West Coast

Federal scientists are monitoring a new ocean heat wave off the U.S. West Coast, a development that could badly disrupt marine life including salmon, whales, and sea lions.

Researchers with the National Oceanic and Atmospheric Administration say the expanse of unusually warm water stretches from Alaska to California. It resembles a similar heat wave about five years ago that was blamed for poorer survival rates for young salmon, more humpback whales becoming entangled in fishing gear as they hunted closer to shore, and an algae bloom that shut down crabbing and clamming.

NOAA Fisheries says the water has reached temperatures more than 5 degrees Fahrenheit above average, though it remains to be seen whether the heat wave dissipates more quickly than the last one. If it lingers, it could be disastrous for the Pacific Northwest’s endangered orcas, which largely depend on chinook salmon. The warmer waters can weaken the food web that sustain the salmon and bring predators of young salmon, including seabirds, closer to shore, further reducing their abundance.

Chinook returns have been extremely low in recent years following the last heat wave.  The new heat wave has emerged over the past few months, growing in a similar pattern in the same area.

Among the causes is a persistent low-pressure weather pattern between Hawaii and Alaska that has weakened winds that otherwise might mix and cool surface waters across much of the North Pacific.

What’s causing that is unclear. It might simply reflect the normal chaotic motion of the atmosphere, or it might be related to the warming of the oceans and other effects of human-made climate change.  (AP)

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