SAN FRANCISCO, April 19 (Xinhua) -- Marine scientists here said Friday that ship strikes were the likely cause of recent deaths of gray whales found in the San Francisco Bay Area.
The Marine Mammal Center, a North California-based private, non-profit U.S. organization dedicated to rescuing and rehabilitating sick or injured marine mammals, confirmed that a gray whale found dead on a beach in Pacifica, California earlier this week died "from blunt force trauma that can be attributed to a ship strike."
This is the second gray whale that scientists confirmed was killed by a ship strike this month.
A necropsy completed Thursday on another gray whale carcass that surfaced last week in Richmond, California suggested the marine mammal died from a ship strike, and it might be the mother of the calf that died from the same cause last week.
Increased numbers of gray whales have been sighted in the area as the population migrates north this spring, the center said.
Investigating each death is critical for decision-makers to advise on shipping speeds in areas where whales are known to travel, said Padraig Duignan, chief research pathologist at the Marine Mammal Center.
Blunt-force trauma from ship strikes, malnutrition and entanglements are the most common causes of death in whales, according to the center's scientists.
Duignan said seven gray whales have been found killed in the San Francisco Bay Area since this year.
Gray whales are one of the most frequently sighted whales in California, and they pass by California in December and January during their southern migration, and again in April and May on their northern journey between Baja California, the northernmost state of Mexico, and Alaska, the northwestern U.S. state, according to the center.