If you find yourself in California's Monterey Bay hoping for a glimpse of some supersized marine life, you're in luck: killer whales are really putting on a show this spring.

The large marine predators, also known as orcas, have converged in the area to hunt gray whale calves – but they're not the type to pass up other dining options. And when an orca gang ambushed a huge pod of common dolphins last week, Capt. Michael Sack of Sanctuary Cruises was just in the right place at the right time to capture all the action.

With reports of orca sightings coming thick and fast, Sack had gone out on the water to see if he could spot any of the animals cruising the bay. "Over the last couple of weeks, we’ve either been seeing killer whales just about every day or we have heard reports of them being seen by other boats. This is the best orca season we’ve had in a few years," he writes on his Captain's Log.

It wasn't long before the distinctive black-and-white predators made an appearance – but things really heated up when the orcas set their sights on an approaching pod of long-beaked common dolphins. With the huge pod heading straight for an ambush, Sack's experience told him to grab his camera.

"I’ve been in this position one other time and I was pretty sure what was about to happen. The next thing I knew there was a huge splash. It was an orca coming up on a common dolphin. The stampede was on after that," he recalls.

The powerful predators are among the world’s fastest-moving marine mammals, capable of reaching speeds close to 35mph (56kph), so this dolphin pod had to race for safety. One casualty can be seen in the water in the aftermath of the attack. 

"It's very rare that everything comes together and we're able to document these types of encounters. We know it happens regularly with the common dolphins. But there's rarely someone there with their video camera focused and waiting for it to happen," says Sack.

And this is just the latest show of orca hunting skills in the bay. Two successful attacks on gray whales were also recorded last week.

Between March and April, Monterey Bay plays host to migrating gray whales as the ocean giants move from their Mexican breeding grounds towards the cold, nutrient-rich waters off Alaska. Young calves travelling with their mothers are an important, high-fat food source for the orcas.

Like other whales, orcas belong to the order Cetacea, but these toothed giants are actually the world's largest oceanic dolphins (and members of the Delphinidae family). Three different orca "types" can be found cruising Californian waters, but the hunters converging in the bay right now are known as "transients". They differ from their close cousins in that they live in much smaller groups (usually made up of females and their offspring), and specialise in hunting other marine mammals.

But exactly why so many of these animals have appeared in the bay this season is not clear. "It could have something do to with the El Niño since we did have some pretty significant differences in the water temperatures and even our small schooling fish count," local naturalist Kelsey Hanyes tells KSBW.

Whatever the reason for this large gathering, local experts agree now is the perfect time for some spectacular whale watching. 


Top header image: timnutt, Flickr