Making a Splash

The whale season to end all whale seasons has scientists searching for explanations

Last year was a
good one for
whales and whale watchers.

That’s when the Monterey Bay and Northern California in general began to see an unprecedented amount of whale activity, particularly from humpbacks. The trend hasn’t shown signs of slowing.

“Over the last couple of weeks there’s been a definite increase in whales, especially blue whales,” says Ashley Englehart, naturalist with SF Bay Whale Watching in Sausalito. “There are more protections in place than ever before, including ships slowing down. The water has also been warmer, which increases the food in the water, so more whales have been coming up to eat.”

It’s not just the humpbacks that have been active. There have been reports about flocks of pelicans in the tens of thousands. All of this activity has led ocean watchers to wonder what the heck is going on. Is this normal? And is it going to continue? Unfortunately, as is often the case with science, there are no easy answers, but scientists do have some intriguing leads.

One of the reasons we are seeing more whales is simply that there are more whales in general. “When I started doing this in the late ’80s, there were only 400 humpbacks,” says Nancy Black, a marine biologist and owner of the whale-watching company Monterey Bay Whale Watch. “But since they’ve been protected, their numbers have increased over the years by 6 percent a year. There are about 2,500 [now].”

But what has been remarkable about this year is that the humpbacks have been sticking around for so long. Typically, they come into shallow waters, eat up what is here, then move on to other feeding spots. These past 12 months, the whales have been more concentrated and slower to move on.

That leads us to the next reason we have seen so many humpbacks: anchovies.

The last year has seen huge numbers of anchovies. The spawn of anchovies is likely related to a 25-year oscillation between anchovies and sardines, a phenomenon that has been catalogued by Francisco Chavez of the Monterey Bay Aquarium Research Institute. Every 25 years, the California coast fluxes between a “sardine regime” and an “anchovy regime.” During a “sardine regime,” there are historically tons of sardines, warmer ocean temperatures off the coast of California and fewer nutrients in the water. An anchovy regime, which we entered at the beginning of the new millennium, is typified by the opposite: cooler water, more nutrients and tons of anchovies.

But in fact, the ocean hasn’t been cold. It’s actually been warmer than average. The warmer waters may be related to a strange wind pattern. Starting in the spring, the winds usually blow from the northwest, causing an upwelling of deeper, colder waters. We had a windy spring, like normal, which likely began the upwelling of these colder waters. These northwest winds usually continue, but not this summer. Instead, we saw lots of south winds, which bring warmer water.

It’s hard to get a clear answer on why the southern winds blew during the summer, because no one really seems to know. “It’s incredibly complex,” said Santa Cruz–based researcher Jodi Frediani. “What I do know is the scientists don’t fully understand it.”

The theory about wind patterns is speculation, and we are likely years away from really understanding what has been going on in the atmosphere. Some scientists are even critical of Chavez’s theory about sardines and anchovies. His data goes back only a hundred years, and older records of marine sediments tracing back thousands of years suggest that there were times when both groups were in high populations.

It’s hard to say if any of this can really be considered “normal,” especially because populations of many marine animals are still recovering from being heavily hunted and fished.

Sonoma County Library