That the California sea lion population is thriving is not news to Morro Bay fishermen, who say the sounds of their boats are like a dinner bell to sea lions ready to snatch fish off the line.
Nor is it news to Morro Bay and Port San Luis harbor patrol officers, who’ve seen firsthand the destruction that heavy, lounging sea lions can cause to boats and docks.
“They are fat and happy right now,” said Matthew Ashton, chief Harbor Patrol officer for the Port San Luis Harbor District, where sea lions hauling onto boats have led to rumors that the heavy animals capsized recreational crafts as large as 30 feet long.
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California sea lions — whose populations dwindled in the middle of the last century from hunting and pollutants like DDT that hampered birth rates — have made a dramatic recovery across the West Coast under the care of the Marine Mammal Protection Act of 1972.
A new study released Wednesday by the National Oceanic and Atmospheric Administration estimates the number of California sea lions has tripled from fewer than 89,000 in 1975 to 257,000 in 2014, reaching what scientists call an optimum sustainable population that’s within a range capped by what the ecosystem can support.
“It’s a good, healthy, strong population,” said Sharon Melin, wildlife biologist with the agency’s Alaska Fisheries Science Center Marine Mammal Laboratory.
That’s great for wildlife viewers, including those who live on or travel to Central Coast beaches and enjoy the cute, playful animals that are iconic to California.
But for boat owners, marina managers and fishermen, the number of sea lions can be challenging. Slowly, they are finding ways to adapt and co-exist.
Fat and happy on the Central Coast
Jeremiah O’Brien, who’s fished the area for 38 years, called sea lions “overpopulated” and said that while predators on land like mountain lions can be hunted when they’re harming local livestock, for example, fishermen don’t have that option.
While they used to keep guns on their boats to protect their haul, the Marine Mammal Protection Act prohibits the harassment, hunt, capture, and kill of any marine mammal, and local harbor patrol officers say fishermen obey.
O’Brien doesn’t believe there is any political will for Congress to overturn the Marine Mammal Protection Act. So, for him, the way to counter sea lions stealing his catch (and livelihood) is to “work faster,” “very frequently move to other areas” or try to trick them by doing things to throw them off, “such as make believe you’re pulling gear.”
In Morro Bay, some docks are lined with electric fencing to keep sea lions off and a floating dock in the middle of the harbor was given up to the sea lions, said Harbor District Supervisor Becka Kelly.
“We’re losing money by not having boats tied there, but maybe we’re saving money by protecting other structures in the harbor by allowing sea lions to congregate here,” Kelly said.
The sea lion dock also created a destination spot for tourists, kayakers and paddle boarders to view the charismatic marine mammals — though some tourists aren’t big fans of how active the local sea lion population is at night. Kelly said visiting hotel guests sometimes complain about their barking.
At Port San Luis, boat owners have tried various efforts to try to prevent the animals from damaging their property — mounting boards with nails, hanging CDS that spin in the wind, spraying the animals with high-pressure hoses, or even shooting them with paintballs, which NOAA actually includes on a list of potential methods of protecting property.
Conflict across the coast
Wildlife managers are aware that a population of a quarter of a million sea lions brings significant challenges and controversy across the West Coast, from them biting swimmers in the San Francisco Bay to preying on endangered salmon on the Columbia River.
“It’s time for celebration on the success of the Marine Mammal Protection Act and time to keep our nose to the grindstone on figuring out how to address the conflict and controversy that comes from having such a large number of (other) animals sharing the coast with such a large number of California sea lions,” said Chris Yates, assistant regional administrator for NOAA’s fisheries resources.
That’s a complicated thing to do, Yates said, because “these animals are very persistent and they’re very smart.”
Not out of hot water
The population boom has not been without periodic declines.
While dozens of sea lions have washed ashore sick with domoic acid toxicosis last year and in years prior, NOAA doesn’t believe the illness — caused when an animal ingests small fish that have eaten toxic algea — presents a large enough threat to cause population-level declines.
Melin said it’s “much more likely to be changes in the prey base and in food that are going to affect them,” which is happening due to extreme weather events.
For example, sea lion numbers have actually dropped from a 40-year high of 306,000 in 2012, which scientists attribute to warming waters that can affect the patterns of the California current that sea lions rely on for food.
Further population declines associated with warmer waters are anticipated in the next couple of years.
Nevertheless, “We anticipate even with those changes, the population would still remain within optimum sustainable population for the foreseeable future,” Melin said.