MONTEREY (CBS SF) – Pods of Orca killer whales have been putting on a show as they troll the waters of Monterey Bay, hunting for baby gray whales to prey upon.

Local whale watching companies are reporting close encounters with the Orcas in larger than usual numbers.

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Gray whales travel through the Monterey Bay waters from March through April as they migrate from their breeding grounds in Mexico to the nutrient-rich Alaskan waters.

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But the migration is not without peril. The Orcas travel south and shadow the migration, hunting gray whale calves traveling alongside their mothers.

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“The killer whales get really excited when they are feeding on the gray whale,” said Nancy Black, a marine biologist with Monterey Bay Whale Watch, told the Monterey Herald. “When they are hunting it, there are lots of underwater calls and communication calls.”

Biologists are watching the frequency of the attacks this year in an effort to see if the warmer El; Nino waters will have an impact.

Since 2013, there has been a decline in the local seal loin population, eliminating a common ford source for the killer whales.

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“It will be interesting to see what happens this spring,” Jim Harvey, marine mammal biologist and director of Moss Landing Marine Laboratories, told the newspaper. “If the orcas have been having a hard time finding prey, there might be more efforts to pick off calves.”