Friday Night Soother: humpbacks for days!
by digby
A couple hundred yards off Mussel Rock, the guano-caked landmark just south of the Daly City cliffs where the paragliders take off, the waters were roiling.
One, two, … four, five … maybe as many as seven humpbacks were romping in the waves, exhaling in great geysers of whale breath. The dark, curved backs rose out the surf and then disappeared into the depths. Gulls circled overhead, waiting for them to return for air.
Every now and then, three would breach together, leaping out of the water together like outfielders converging for a full-body bump.
Those whale sightings occurred a couple of weeks ago, but since early May unprecedented numbers of the marine mammals, mostly humpbacks but some grays and even a few blues — the largest creatures on earth, have been gathering off the shores of San Francisco, Marin County and San Mateo County.
Dr. Jaime Jahncke, California Current group director for Point Blue Conservation Science, told Golden Gate Parks Conservancy, that he saw 30 to 80 whales every day during an eight-day research expedition in May.
“This is the first time we’ve had such great numbers [of whale sightings] this early in the year,” Jahncke said. “Generally, the peak numbers have appeared in July. Historically, large numbers are expected in the fall and not in the summer.”
So why are so many whales congregating off the coast so early this year?
Anchovies.
Humpbacks love anchovies, and Dr. Sara Allen, who heads the Ocean and Coastal Resources Program for the Pacific West Region of the National Park Service, thinks an abundance of the silvery fish, along with other prey, is attracting them.
“You’ve got a tremendous narrow passage into the estuary so everything is compressed; physically it concentrates the prey [along the tidal zones],” Allen told Golden Gate Parks Conservancy.
So basically, the Golden Gate Strait and surrounding waters have become one giant cetacean seafood buffet.
La Nina conditions may be stirring up nutrients that fish can’t resist. The small fry in turn are devoured by humpbacks, which unlike blue whales supplement their krill diet with the likes of anchovies, sardines and other schooling fish. The closer humpbacks are too the coast, the more likely they are feeding on fish.
But there could be other explanations. The whales’ presence could also indicate an inadequate krill population, forcing the humpbacks to look elsewhere for food, Jahncke said.
Or a scarcity of krill and fish at the whales’ breeding grounds off Mexico and Central America could have induced the creatures to head north earlier than usual, he said.