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Richardson Bay Sea Otter, First in San Francisco Bay Since 2011, Dies

by on July 16, 2015

A sea otter swims past cyclists on the Sausalito-Mill Valley trail. (Photo by youtube user NorthwesternPacificHistoryIsCool)
A sea otter swims past cyclists on the Sausalito-Mill Valley trail. (Photo by youtube user NorthwesternPacificHistoryIsCool)

A young southern sea otter that had spent the last several weeks living in Richardson Bay died over the weekend.

The otter, a 3-to-4 year old male, was found on Saturday and sent to California Department of Fish and Wildlife for a post-mortem examination, which veterinary pathologist Melissa Miller said ruled out some causes of death, but did not confirm one.

“The findings are very nonspecific,” Miller said. “He was skinny. He didn’t have much in the way of subcutaneous fat. There could be some issues around biotoxins or other types of things. But we didn’t see any evidence of foul play, like a gunshot wound, or evidence of boat strike.”

It was the first confirmed sea otter in San Francisco Bay since one was spotted off Alameda in 2011, and only the 16th “credible report” since 1979, said US Fish and Wildlife Public Affairs Officer Ashley Spratt. Still, she said, while southern sea otters cluster mainly around the coast between San Mateo and Santa Barbara Counties, the Bay is part of the otter’s historic range, and young male otters are known to range widely, from Tomales Bay in the north to San Diego County in the south.

“The piece that’s really interesting is that range expansion for southern sea otters is absolutely essential for their recovery,” Spratt said. “They have reached their carrying capacity in the central portion of their range, based on available food supplies. So this report is not an indication of range expansion, but it is an indication that there are the resources there that would support otters.”’

A sea otter feeds on a mussel in Richardson Bay in early July. (Photo by youtube user NorthwesternPacificHistoryIsCool)

A sea otter feeds on a mussel in Richardson Bay in early July. (Photo by youtube user NorthwesternPacificHistoryIsCool)

The southern sea otter has been on the Endangered Species Act’s threatened list since 1977, and has slowly recovered from near-extinction in the 1930s. The population has grown to roughly 2,900 otters, according to a 2014 report from the US Geological Survey, which does annual counts of the southern sea otter population.

The Richardson Bay otter arrived sometime around late June or early July, and was spotted eating clams and shellfish, grooming, and resting near the path leading from Sausalito to Mill Valley. A YouTube video posted by the user NorthwesternPacificHistoryIsCool shows the otter swimming near the shoreline and around the Highway 101 bridge.

Biologists observed it regularly, and The Marine Mammal Center had put up signs warning kayakers and boaters to give the otter space. Its carcass was first reported to TMMC, which then sent it to Miller for a necropsy.

The otter had full adult teeth, but little wear and tear on them, Miller said. Based on a still-open suture at the base of its skull, she estimated the age at 3-4 years. While it was still in Richardson Bay, observers saw the otter have an apparent seizure, Miller said, which suggests neurological disease. A recent algal bloom in Monterey Bay has led to a high level of the biotoxin domoic acid in the water, and TMMC Public Relations Specialist Laura Sherr said the rescue center has seen a high number of sea lions suffering from domoic acid poisoning in the last month, with symptoms including seizures.

But seizures could also be the result of low blood sugar in an emaciated animal, Miller said. She’ll need to do biotoxin tests, and look at tissue samples under a microscope, before she can better determine what caused the otter’s death.

An otter near the pickleweed in Mill Valley. (Photo by youtube user NorthwesternPacificHistoryIsCool)

An otter near the pickleweed in Mill Valley. (Photo by youtube user NorthwesternPacificHistoryIsCool)

There were also two unusual things about the otter’s life. Although Alaskan sea otters eat fish, southern sea otters rarely do – but this otter, Miller said, seemed like it had.

“It’s very unusual to see roundworms in sea otters in California,” Miller said. “This one had a few in his stomach. When we see that, usually it means that the otter ate fish in its life.”

It also had thinning hair around its lips, which Miller said might be a kind of mange – southern sea otters have their own mange-causing mite, which has never been described — although it’s not something she can determine without a microscope. She’s waiting now for tissue slides to return from UC Davis.

“The process is such that we want the animal to tell their whole story,” Miller said. “How he died, why he died, what that might mean in the bigger picture. And also how he lived.”

See more articles in: Wildlife: Birds, Mammals, Fish

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9 comments:

Mary on July 17th, 2015 at 12:16 am

hi
I’m so sad to hear he died. I have video of him from June 30 2015. If anyone would like it email me. The first and last time I saw him.

Dana Michaels on July 17th, 2015 at 8:18 am

Californians who would like to support Dr. Miller’s work for our sea otter population can do so on your state income tax return. The California Sea Otter Fund is on line 410 of the main tax form (540) under Voluntary Contributions. The money donated supports sea otter conservation programs at the State Coastal Conservancy and the Dept. of Fish and Wildlife. Details are at http://www.facebook.com/SeaOtterFundCDFW. Thanks!

Bay Nature Staff on July 17th, 2015 at 4:30 pm

Hi Mary, We’d love to see your video. Thanks for offering to share it with the Bay Nature community! – Beth, Bay Nature Outreach (outreach@baynature.org)

stella witt on July 19th, 2015 at 1:26 pm

I guess he did of plastic

Mary on July 19th, 2015 at 10:47 pm

hi Beth ,
I sent the videos to your email. They’re short and it was dusk but maybe they’ll give you some additional insights. If you want details about where it was exactly let me know
Thanks for all you do!

Bob on July 28th, 2015 at 6:06 am

should’ve fed him, he obviously died of starvation, all those idiots passing him by saw that he was starving to death and did nothing, so pathetic, pointless and utterly stupid, like I suppose most San Franciscans are, most diseases are as always a results from weakened immune system from starvation. I’m not talking about dependence, Im talking about helping a kid, with no experience in a strange place getting past a hard time, just like you would help a homeless person or someone who lost their job and wouldn’t let them starve to death.

Starving Otter Thanks guys for nothing on July 28th, 2015 at 6:34 am

Feeding him a temporary amount of food, like several bags of dog food (yes they can eat it, they are mainly calorie restricted not nutrient restricted) would’ve given him the energy store necessary to leave the mud flats and find food (yes a few dollars on your part). How stupid are these biolgist that they don’t know that sea otters can’t survive in mudflats for long. Whats worse is the public, and people who can’t reason and think for themselves and blindly follow doctrine (don’t feed the animals).

DearBob on July 29th, 2015 at 5:31 pm

He was eating all the time. Did you not watch the videos–it’s just pictures of him eating mussels and crabs. Maybe you have a different definition of “eating” Bob?

In any event, we will forward your insights to the DFW pathologist.

Chris on August 12th, 2015 at 10:31 am

Average bystanders Feeding a wild animal? Otters are protected, approaching within 50-feet is forbidden by law. This otter had something wrong more than just nutrition. I witnessed this otter fall asleep 10 feet from a busy bike path, dogs, tourists and humans all over. A wild otter in its right mind would find a safer place to rest.

What would Bob had done? Fed the otter a cheeseburger? I notified several Marine Mammal agencies as I am not a biologist, and it’s not an average citizen’s responsibility to save wild animals. By and large, for humans and animals to coexist, we must give them space, keep it clean, and non-experts should not approach or interfere with the animals.

Animals die every day, it’s how nature works, it’s not humans responsibility to save every creature in trouble.

Bob, Don’t be a troll (see https://en.wikipedia.org/wiki/Internet_troll ) … Sober up, enroll in some classes at city college so you don’t have to go through life being an uneducated prick.

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