Killer whale
Information for offshore regions and warmer waters is more scarce, but widespread sightings indicate the killer whale can survive in most water temperatures. They have been sighted, though more infrequently, in the Mediterranean, the Arabian Sea, the Gulf of Mexico, and the Caribbean. Over 50 individual whales have been documented in the northern Indian Ocean, including two individuals that were sighted in the Persian Gulf in 2008 and off Sri Lanka in 2015. Those orcas may occasionally enter the Red Sea through the Gulf of Aden. The modern status of the species along coastal mainland China and its vicinity is unknown. Recorded sightings have been made from almost the entire shoreline. A wide-ranging population is likely to exist in the central Pacific, with some sightings off Hawaii. Distinct populations may also exist off the west coast of tropical Africa, and Papua New Guinea. In the Mediterranean, killer whales are considered "visitors", likely from the North Atlantic, and sightings become less frequent further east. However, a small year-round population is known to exist in the Strait of Gibraltar, mostly on the Atlantic side. Killer whales also appear to regularly occur off the Galápagos Islands.
Blue whale
Blue whales may be wounded, sometimes fatally, after colliding with ocean vessels, as well as becoming trapped or entangled in fishing gear. Ship strikes in particular have killed many blue whales in California. In September 2007, three dead blue whales washed up in southern California after being killed by ship strikes. A similar incident occurred in northern California in 2017, possibly also 2010. Ship strikes are also a serious problem in Sri Lanka, and scientists believe this problem could be nearly eliminated by moving the shipping lanes 15 nautical miles to the south. The ever-increasing amount of ocean noise, including sonar, drowns out the vocalizations produced by whales, which makes it harder for them to communicate. Blue whales stop producing foraging D calls once a mid-frequency sonar is activated, even though the sonar frequency range (1–8 kHz) far exceeds their sound production range (25–100 Hz). Research on blue whales in the Southern California Bight has shown that mid-frequency sonar use interferes with foraging behavior, sometimes causing the whales to abandon their feeding. Human threats to the potential recovery of blue whale populations also include accumulation of polychlorinated biphenyl (PCB) chemicals within the whale's body.