Delta and Dawn

[3] Staff from the Marine Mammal Center, researchers, Coast Guard personnel, and volunteers tried several methods to coax Delta and Dawn back downriver.

[1][4] The Marine Mammal Center was appointed by the California Office of Emergency Services as the lead rescue agency.

[3] Officials played recordings of the sounds of other humpback whales feeding and socializing to lure them,[5] and banged on submerged metal pipes and sprayed high-powered blasts of water to repel them, but it is not clear whether any of these were particularly effective.

[6] There was heightened concern for the whales' well-being this time, because both of them had sizable gash wounds, most likely made from boat keel or propeller strikes.

[7][8] On May 20, after languishing for six days in the Sacramento Deep Water Ship Channel, the whales finally started moving.