MOSS LANDING>> The Elkhorn Slough is booming with baby sea otters, which is a good thing for the ecosystem and the animals, scientists say.
The estuary is home to 12 otter pups of varying ages, according to the latest scientific count. Tim Tinker with the U.S. Geological Survey and a team of scientists from the Monterey Bay Aquarium, Elkhorn Slough National Estuarine Research Reserve and the California Department of Fish and Wildlife, have tagged 25 animals since the fall of 2013 to understand sea otter behavior and ecology.
Though female otters can get pregnant year round, November through March is peak season for births in California. The number of pups in the slough currently is similar to previous years, Tinker said.
“The fact that they are reproducing and it’s been a healthy thriving population is really quite exciting,” said Tinker. “It tells us, and we are still learning about this, that otters can thrive in an estuarine environment.”
But counting pups is tricky. The number is always changing as new pups are being born and older pups are being weaned, said Tinker.
“Females with pups tends to hide out in tidal creeks,” he said. “Those creeks are off-limits to general public.”
But the count may now be up to 13. Thursday morning a new otter pup entered the world.
“We discovered the brand new pup around noon, about a mile into the slough,” said Joe Mancino, owner of the Elkhorn Slough Safari Nature Tours.
About 80 total sea otters call the estuary home.
“All the females we tagged have never left the slough once,” said Tinker. “They live there and that’s their entire universe.”
At times, the number of otters in the slough can reach up to 120 animals. But those extra animals are transient, meaning they come and go from the estuary, he said.
Otters have only been living full-time in the slough since the early 2000s, according to Tinker.
Historically, thousands of otters inhabited San Francisco Bay and other estuaries along the coast, he said. But in the early 1900s the fur-trapping industry nearly wiped otters out from much of their native range, which spans from Russia, across the Aleutian Islands and down the West Coast of California.
Otter populations plummeted from several hundreds of thousands down to roughly 2,000. Now, they have bounced back to around 3,000 animals. And as they recovered, they have moved back into the Elkhorn Slough, said Tinker.
“One day, it will be someday down the road, they will be back in San Francisco Bay, Drakes Estero and Tomales Bay,” he said.
And that is potentially a good thing.
The return of otters to Elkhorn Slough has had positive effects on the ecosystem health. When the otters came in, they mostly ate the crabs, said Tinker. The crabs eat small marine critters such as sea hares, which graze on algae that coats the eelgrass. So with fewer crabs and more algae grazers, the eelgrass could thrive.
“We went from a situation in Elkhorn Slough having least healthy eelgrass beds, being choked out by algae to now having healthiest eelgrass beds on the West Coast,” said Tinker.“ As far as we can tell, that’s entirely due to the return of otters.”
The otters in the slough have relatively sheltered lives. Bites from white sharks are the biggest threats to coastal otters, said Tinker. But the slough otters have fewer predators and also can rest onshore.
Rest is very important for otters. During a period of 24 hours, otters feed in five to seven bouts throughout the day. In between those bouts they need to sleep and get their body temperature back up, Tinker said.
One of the biggest concerns for otters in the slough is getting disturbed from kayakers that approach sleeping otters too closely, he said.
“It’s really important for them when they are resting to get dry and stay dry because that’s what reduces their temperature loss to the marine environment,” said Tinker.
Otters are an endangered species, which also means it is illegal to disturb them.
To view the Elkhorn Slough otter cam, visit www.elkhornslough.org/ottercam.
