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Ocean Feast: Humpbacks and sea lions and hundreds of thousands of birds – oh my!

By Linda Hunter
Published: August 2007

humpback lungefeeding
Humpback lungefeeding. Credit: M Fotheringham

On July 28th, an intrepid group of wildlife enthusiasts left the Marina Harbor in route to the Farallon Islands aboard the SuperFish with veteran captain Mick Menigoz and naturalist and marine biologist, Carol Keiper.

Though the seas were rough, the passengers were rewarded by an amazing display of wildlife. Just north of the islands, they could see hundreds of sea lions porpoising in the surf while seabirds dove raucously from above. Then, in their midst, five blows – humpback whales!

Captain Mick cut the engine and the boat drifted in the choppy waters. Whales were suddenly right alongside, then under the boat, including a mother and calf that appeared out of nowhere. There were  breaching whales and synchronistic tandem lunge feeding (fast, horizontal surfacing with mouths open). All this incredible activity hopefully indicates a successful upwelling this year, which results in plenty of food in the nutrient-rich waters just off our coast.

Sea lions feeding at the farallones.Nature threw a different wrinkle at the California Current system in 2005, when the spring upwelling was delayed by a month. Winds that normally cause upwelling were absent, creating the lowest "upwelling-favorable wind stress" in 20 years. Near-shore waters were two degrees (C) warmer than average, surf zone chlorophyll levels were 50 percent of normal, and nutrient levels were reduced by one-third. Changes in water movement, triggered by the wind shifts, had a drastic effect on mussel and barnacle larvae, which decreased by 83 and 66 percent respectively.

In 2005 and 2006, researchers found thousands of starving birds washing up on shore. Scientists trying to predict salmon runs recorded large swings in ocean temperatures at a much higher frequency than the past, a change that signals large shifts in the amount of food available for salmon, birds, and marine mammals. Scientists linked the low oxygen zones and animal die offs to changes in the timing and strength of upwelling, a usually reliable and regular wind-driven process that brings cold, nutrient rich waters up from the depths of the ocean and fuels productive coastal ecosystems.

Oregon State University's Jane Lubchenco, a co-organizer of the West Coast variability symposium and past president of the AAAS, said the bottom line is that the dramatic events of the past few years have shown how vulnerable our oceans are to changes in overall climate – and how quickly ecosystems respond.

Two humpback surfacing by the Farallones."Wild fluctuations in the timing and intensity of the winds that drive the system are wreaking havoc with the historically rich ocean ecosystems off the West Coast," Lubchenco said. "As climate continues to change, these arrhythmias may become more erratic. Improved monitoring and understanding of the connection between temperatures, winds, upwelling and ecosystem responses will greatly facilitate capacity to manage those parts of the system we can control."

We hope to be experiencing an abundant upwelling this year – to the delight of humpback whales and all species dependent on this phenomenon.