Sea otters, which can eat nearly 1,000 sea urchins a day, have seen their numbers along Alaska’s Aleutian Islands shrink by 90 percent in recent decades. When otter populations recovered after trapping was restricted, the reef rebounded, too. Some researchers think it’s because federal laws have protected elephant seals, sea lions and other marine mammals that the sharks eat, growing their numbers. The concept is still in the early stages. Fur traders in the 18th and 19th centuries hunted the animals to the brink of extinction, allowing sea urchin numbers to skyrocket, Dr. Rasher said. The loss is more than cosmetic. Dr. Estes suspects that starving orcas — perhaps deprived of their preferred whale prey by industrial whaling — have turned in desperation to the little mammals, which they can gulp down by the hundreds or thousands a year. It’s a place they haven’t inhabited for nearly 200 years, but some fishermen might not be ready to welcome them back. But against the backdrop of climate change, Dr. Rasher said, the reef’s safety net is gone. The smooth-coated otter is listed as "vulnerable" (has a high risk of extinction), and the Eurasian and Asian small-clawed otters as "near threatened" (has a potential future risk of extinction). Protected by the Endangered Species Act in … “There are a lot of stakeholders and understanding the needs and concerns of all of those alongside the data and the concerns and the modeling of the scientists is going to be a really rich discussion.”. He was greeted by an ocean filled with furry faces. “San Francisco Bay is a busy place with a lot of things going on,” said Rudebusch, lead author of the study. Alaskan reefs, built by the coralline algae C. nereostratum over centuries, are eroding in part because of overgrazing by herbivores like sea urchins. “They eat them like popcorn,” Dr. Estes said. Dungeness crab was a $51.8 million fishery last year, said Mike Conroy, executive director of the Pacific Coast Federation of Fishermen’s Associations in San Francisco. People actively hunted for the sea otters’ wool in the 18th century, which meant destructive influence for the species, and sea otters began to occur less frequently and less frequently in the natural habitat. They were feared extinct until the 1930s, when about 50 were discovered in remote Big Sur coves. Everywhere the young biologist looked, there were sea otters — lollygagging on kelp beds, shelling sea urchins, exchanging their signature squeals. Big cities, ports and heavily trafficked areas, such as the Golden Gate and Bay bridges, and the Oakland waterfront, pose the highest risk. Aleutian sea otters have been in flux before. Over the last decade, however, the number of shark attacks on otters has grown. Since the 1990s, the Aleutian sea otter has been "functionally extinct," researchers said. IJ reporter Will Houston contributed to this report. The aquarium has released dozens back into the wild, most notably at Elkhorn Slough, an estuary near Moss Landing full of tidal marshes, creeks and muddy channels — similar to San Francisco Bay. To happen, it would require approval from the U.S. In the past several decades, a glut of carbon dioxide in the atmosphere has acidified ocean waters, making it harder for algae to armor themselves. In just a few decades, this bustling civilization has withered into a ghost town. But there is a growing momentum, with backing from prominent institutions such as the Monterey Bay Aquarium. Shark bites are a frequent cause of injury for the otters they care for, he said, but there are also cases of malnutrition and parasitic infections. Softened by warming and acidifying waters, the coral-like structures have quickly succumbed to the urchins’ tiny teeth, which can annihilate years of fragile algae in a single bite. The research analyzed hazards — including large commercial ships, high-speed ferries, oil spills, fishing gear and toxins such as mercury. But the 1-million-acre bay has enough food — crabs, clams, mussels and worms — to support up to 6,600 otters, a major study last December found. Although the urchins eagerly descended upon the local smorgasbord of kelp, the bubblegum-pink reef beneath them seems to have persisted — in part because healthy algae produce a protective limestone layer that can thwart even the most determined grazers. Changes yet to come will likely prompt the grazers to pick up the pace even more, the team’s analysis showed, barring sweeping change in carbon emissions. Related Articles The key might be moving them into San Francisco Bay — away from great white sharks, Marin animal care centers report distemper outbreak, Marin Voice: Crab fisherman concerned ‘ropeless’ gear not best answer, | Natural resources and environment reporter, Heating failures vex Marin City public housing residents, Point Reyes National Seashore gets new superintendent, Big Basin redwoods: Drone video shows extent of wildfire over famed state park, Marin officials weigh grant requests by nonprofits. That could be a difficult task, given the probable cause of the Aleutian Islands’ stunning vanishing of otters. “For the conservation of the sea otter, this would be huge.”. Protected by the Endangered Species Act in 1977, they began a slow comeback. And they have flourished. Back then, crowds of these charismatic creatures shrouded the sprawling archipelago, congregating in “rafts and bunches, as many as 500 at once,” said Dr. Estes, an ecologist at the University of California, Santa Cruz. Many lived in San Francisco Bay, but by the Gold Rush, they were all but gone. They reproduced. Sea otters today are considered a species that is endangered. The thinking: What if several dozen otters were moved under the Golden Gate Bridge into the bay? In 1986, river otters were listed as an endangered species in Nebraska. There are political challenges. They can’t expand their coastal range any farther north than Pigeon Point in San Mateo County because the area is thick with great white sharks. Sea otters were hunted to near extinction during the maritime fur trade of the 1700s and 1800s. “The idea with reintroduction is to put otters back in an area where they used to be,” said Jessica Fujii, assistant manager of sea otter research at the Monterey Bay Aquarium. “For their size and how cute they are, they are aggressive eaters.”. “There was this incredible diversity,” he said. Marin Voice: Crab fisherman concerned ‘ropeless’ gear not best answer When most people think of California sea otters, the kelp beds of Monterey Bay and Big Sur’s rocky shoreline often frame the backdrop. While he is hopeful that further research into reintroducing otters to the bay will show promising results, Boehm said more research and input from all stakeholders who use the bay is needed before a decision should be made. “Predator loss can impact the environment in ways we haven’t even thought of,” Dr. Griffin said. “It was spectacularly beautiful.”, When the Otters Vanished, Everything Else Started to Crumble. I don’t think we know yet.”. “Will it result in negative impacts to other species? “And temperature exacerbates that issue.”. But the otters basically disappeared in the 18 th and 19 th centuries, after being hunted almost to extinction for the fur trade. Warmer temperatures also speed animal metabolism, driving urchins to eat even more enthusiastically than usual. That’s because they eat crabs, which eat sea slugs, which in turn eat algae on eel grass. Sea otters were locally extinct in British Columbian waters in Canada, until a plane containing a romp of otters arrived and set off a population boom – with unintended consequences. The aquarium has proven that otters don’t need rocky shorelines and kelp forests to thrive. “The reefs are producing less dense skeletons,” Dr. Rasher said. Using “surrogate mother” otters that live at the aquarium, the orphans learn how to feed, groom and socialize.
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