Subsequent to the deaths of five whales in the Santa Barbara Channel, a sixth whale washed ashore Ventura County’s Sea Cliff area this past Sunday.
Scientists suspect the beached behemoth, identified as a 45-foot long female Grey Whale, died two to three weeks prior to its discovery, rendering much of the carcass’ tissue unviable for lab tests. However, researchers at the Santa Barbara Museum of Natural History do not associate the whale’s death with prior fatalities, dubbed Unusual Mortality Events (UMEs) by the National Oceanic and Atmospheric Administration’s National Marine Fisheries Services (NMES) in January.
Marine mammals strand for various reasons, including biotoxins, illness, separation from their mothers, entanglement in fishing gear, injury and natural causes. According Museum vertebrate zoologist Michelle Berman, the whale’s death coincides with the seasonal migration pattern of the Grey Whale. “It’s actually very common this time of year; we usually see one or two grey whales wash up per year,” said Berman. During the winter and spring months, around 20,000 Eastern Pacific migrate along a narrow lane between the Santa Cruz and Santa Rosa Channel Islands towards the Baja Peninsula.
Museum spokesperson Easter Moorman concurred that there are several criteria which characterize a UME, none of which the recently deceased fall under, leading researchers to believe the death was related to its natural migration.
“We necropsy about 25 animals a year through our team here, and they keep a record,” said Moorman. “Death is part of the circle of life; things happen along the way [of the whales’ migration]. It may have died from natural causes, infection; it could have been attacked by a shark, [but there is] no evidence of it being hit by a ship or propeller.”
Moorman noted that cuts in the four- to five-ton animal appear post-mortem, though experts still find the cetacean’s death inconclusive. However, the five previous Blue whale deaths - three of which are attributed to the impacts of large vessels - have raised concerns with the Environmental Defense Center and Channel Island National Marine Sanctuary Council. Though necropsies have ruled out domoic acid - a neurotoxin found in algae that can throw off the navigational abilities of the whale if consumed - as a cause of death, and have found no traces of sonic pollution, investigations will continue.
On February 21, Berman and partnering zoologist Paul Collins will give an update of their Blue Whale investigation, and will discuss the process used to determine the cause of deaths for marine mammals. The presentation will be held at 7 p.m. at the Museum’s Ferrand Hall.