Four gray whales have turned up dead in the San Francisco Bay over a week and a half, sparking concerns about the whale population in the region.
There are fears that the recorded gray whale deaths could represent just a small fraction of the amount of whales that are dead in the water, with experts unclear on how at least two of them died and calling the spate of deaths ‘shocking’.
The carcass of the first whale, an adult female 41ft long, washed ashore at Crissy Field in San Francisco on March 31.
Three days later, a second adult female whale was found at Moss Beach in San Mateo.
Pictured: A dead whale that was found in the Berkeley Marina with an unknown cause of death
This is the adult female gray whale that washed ashore on Thursday, struck by a ship
‘That animal’s cause of death, we suspect, was ship strike,’ Giancarlo Rulli of the Marine Mammal Center said to SFGATE, though that hasn’t been confirmed.
On Wednesday, a third whale was found floating near the Berkeley Marina, with a fourth whale found on Thursday at Muir Beach in Marin County.
The manner of death of the fourth whale is the only one definitively known so far, as it was struck by a ship.
A necropsy of that whale revealed significant bruising and hemorrhaging to the muscle around the jaw, as well as the neck vertebrae.
The whale was in good condition prior to the fatal ship strike.
‘It’s alarming to respond to four dead gray whales in just over a week because it really puts into perspective the current challenges faced by this species,’ said Dr. Pádraig Duignan, director of pathology at the Marine Mammal Center, according to The Guardian.
So far, four whales have appeared dead in the San Francisco Bay since March 31
At least 13 dead whales appeared in the Bay Area in 2019.
Half of the whales who died in 2019 were due to malnutrition, which will take further investigation to potentially apply to the recent whale deaths.
‘This many dead whales in a week is shocking, especially because these animals are the tip of the iceberg,’ legal director of the Center for Biological Diversity’s oceans program Kristen Monsell stated.
Experts believe the four dead whales of the past few days may represent as little as 10 percent of the amount of deceased whales in the water, as many sink without being noticed.
The San Francisco Bay (stock). Humans and climate change play a major role in endangering whales, with less prey in the ocean and more opportunities to be entangled in nets
There are many different threats to whales in the ocean, including the effects of climate change, which has heated up the ocean and limited the availability of prey.
The use of fishing gear and ship strikes can also play a part in hurting the whale population, as the latter did with the most recent whale.
In the most recent population surveys from 2015 and 2016, the National Ocean and Atmospheric Administration reported one in four gray whales with migration patterns across the West Coast died.
Whales typically migrate to Mexican waters in the winter, where they mate, before traveling up to California in the spring and summer en route to the Arctic.
Pictured: A whale that washed up dead at Point Reyes National Seashore near San Francisco in 2019
The Marine Mammal Center is challenged to perform its investigations due to the COVID-19 pandemic.
‘We’re deploying smaller teams than normal, and these are 40-foot-plus whales, these investigations take hours,’ Rulli said.
‘It can take some time to figure out what’s happening.’
Meanwhile, a humpback whale was spotted near Tiburon in mid-March, the earliest in the year that’s ever occurred.
According to the Associated Press, the Center for Biological Diversity is suing the federal government in an attempt to have speed limits added to shipping lanes to help avoid these kinds of fatal whale strikes.
‘Ship strikes and fishing gear entanglements kill many whales that we never see,’ Monsell said.