Around 30 killer whales were spotted playing in Monterey Bay for more than eight hours on Sunday. Six of the whales were also captured in April attacking adult gray whales in a rare encounter. "It was the best killer whale encounter I've had and I've been studying them for 30 years," Nancy Black, a marine biologist with Monterey Bay Whale Watch and director of the nonprofit California Killer Whale Project, told Insider. Monterey Bay Whale Watch said the gray whales ultimately survived the attack but were badly injured. The unusual playful display comes as killer whales near Spain and Portugal have increasingly been damaging and even sinking boats.

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Persons: —, I've, Nancy Black, Evan Brodsky, Black, Insider's Joshua Zitser, Daniel Bianchetta, they've Organizations: Service, Sunday, Whale Watch, Whale, grays Locations: Monterey Bay, Monterey, California, Spain, Portugal