Blue whales trying to feed amid a people frenzy

The presence of so many blue whales within easy viewing range off Southern California has been one of the big outdoor stories of the summer.

Earth’s largest creatures—blue whales can reach 90 feet and weigh 150 tons—have been lured to nearshore waters off L.A. and Orange counties by dense blooms of shrimp-like krill. The mammals are so focused on feeding that they’ve allowed for uncommonly close encounters.
But contrary to some reports the whales are not here in record numbers. They’re simply distributed differently and are more accessible than in previous summers, so only the sightings have vastly increased. And while this represents a boon for local whale-watching operations, and a treat for marine mammal enthusiasts, it’s not necessarily good for the whales, who are trying to feed in a busy shipping zone and amid bustling small-boat traffic.

A particularly dense concentration of these majestic leviathans—perhaps as many as 50—is just beyond Los Angeles Harbor, off the Palos Verdes Peninsula. Scientists have seen whales with fresh wounds and have witnessed close calls between whales and boats. “I would say there’s a potential risk to the whales because of the fact that we have these concentrations in some of the busiest waters almost anywhere,” said John Calambokidis, a co-founder of the Olympia, Wash.-based Cascadia Research collective and a leading authority on blue whales.

Calambokidis is among several researchers studying blue whales off Southern California. One study will document how the cetaceans react to ship noise, so steps might be taken to mitigate the risk of vessel strikes. Blue whales are endangered. There are about 10,000 worldwide and about 2,000 that utilize California waters during the summer. This latter group is believed to spend the winter at a remote seamount west of Central America, called the Costa Rica Dome. These whales migrate into California waters specifically to fatten up on krill, which flourishes in cool, nutrient-rich water. Though whale sightings occur off Orange and Los Angeles counties, the thickest concentrations of blue whales --where the densest concentrations of krill typically exist—are generally off Santa Barbara and points north.

This summer, unseasonably cool water off Southern California has resulted in more krill and, thus, longer-lasting whale visits. “I don’t know of a previous occurrence of this many whales in this particular area,” said Calambokidis, referring to an area between Newport Beach and Los Angeles. He said at least 50 different whales are in this area but added, “It’s conceivable that there are a couple of hundred.” It remains unclear how many, if any, have been struck by boats. One or two blue whales are known to be killed by vessel strikes off California annually. Many more collisions, unseen and undocumented, are believed to occur.

A Monterey Bay whale-watching boat struck a blue whale a month ago off that Central California port. More recently, a 75-foot blue whale carcass washed ashore on San Miguel Island off Santa Barbara. Scientists have yet to inspect the mammal to determine the cause of death. Unfortunately, Calambokidis said, blue whales do not seem to be making an effort to avoid approaching ships, and they might actually spend more time at the surface when ships are close by.

The scientist added that blue whales tend to spend more time close to the surface after dark, “making them vulnerable ship strikes, particularly at night.” Given all this, Southern California ship captains and boaters are urged to exercise caution for as long as the whales are present. They’ve got a lot of fattening up to do—a single blue whale can consume four tons of krill per day—and it must be hard to eat with all those people watching.