Orcas, popularly known as killer whales, are invading Monterey Bay off the California coast in search of food.
Orcas, which are actually a species of dolphin, are frequently spotted off Monterey in April and May. But this year they are appearing in record numbers to hunt and feed on gray whale calves migrating from Mexico to the Arctic with their mothers.
"That is why we are seeing so many of them this time of year, because as those gray whale calves are migrating back up north, they are coming around hunting, patrolling for them," Britt Simon with Discovery Whale Watching told KSBW.
In late April, observers spotted a group of about 50 orcas in the bay after a family feeding on a gray whale calf were joined by newly arriving pods.
“It was like a big killer whale bonanza," Nancy Black, marine biologist with Monterey Bay Whale Watch, told The San Francisco Chronicle. "It became more of a social event and less about the feeding. Each family group was greeting each other and mixing around."
Randy Straka, photographer with Princess Monterey Whale Watch, told the publication that he’d never seen so many orcas at once.
"It's actually very exciting, and a bit overwhelming,” he said. “And a bit like a three-ring circus, not knowing which group to focus on.”
The geography of Monterey Bay gives orcas the advantage when hunting gray whales, according to The Mercury News.
“Most of the time gray whales swim tucked up to the shore in shallow water close to the kelp beds that provide shelter from killer whales who prefer deep, open ocean waters,” Ari Friedlaender, an associate researcher at UC Santa Cruz, told the publication. “However, due to the contour of the bay at some point whales have to pass over the canyon and out to the expansive ocean to continue their migration leaving them vulnerable to attack by killer whales.”
In the past six weeks, orcas have successfully attacked gray whales at least seven times off Monterey, The Mercury News reported. Black told the publication that orcas also feed on seals, sea lions and dolphins in the bay.
"For some people coming out it is a little heart-wrenching for them to see the attacks on these baby gray whales, so we do kind of have to warn people," Erica Wolff with Princess Monterey Whale Watching, told KSBW.