A marine biologist who recently completed a study on sea lions and harbor seals in and around La Jolla Cove has concluded that deterring the marine mammals from coming ashore is going to be easier said than done.
Dr. Doyle Hanan, of Hanan & Associates Inc., at the City of San Diego’s request, recently submitted the results of his year-long research on local pinniped populations and their behavior. Hanan concluded that the “California sea lion populations and resulting interactions with humans are likely to increase over time.”
In the Hanan study, observations of sea lions and their behavior were made from 10 sites around the Cove where the marine mammals haul out. The marine-mammal expert has subsequently offered several options to attempt to stem the unwanted presence of sea lions on La Jolla’s cliffs and the Cove beach.
Hanan noted his recommendations “all have advantages/disadvantages and varying costs for installation/maintenance.”
Those options:
• Use only NOAA-approved deterrence methods, i.e. non-lethal “boarding” to bar their way or spraying with hoses, etc.
• Install gates and latches at access points.
• Employ strong fencing as a deterrent.
• Consider using low-voltage livestock fencing.
In existence for 16 years, Hanan & Associates specializes in research on marine mammals and fish working on federal, private and commercial contracts.
Concerning his recently completed Cove pinniped study, Hanan said, “It was a behavioral study. We were looking at the abundance of sea lions by season, sex and age.”
Noting “no work had ever been done like this in La Jolla,” Hanan pointed out there were no (research) references to be had.”
Hanan said the city was looking into potential solutions to sea lions and the problems they’ve brought – foul (cliff) smells from their waste, their pollution in the Cove where people swim and their increasing movement onto the beach displacing people and hampering lifeguards in performing their duties.
Sea lion numbers, not only locally but all along the West Coast, have been rising for decades. Hanan noted that’s been happening, in part, because they’ve been protected from being “taken” by federal law since the Marine Mammal Protection Act (MMPA) was passed in the ’70s. Hanan expects pinnipeds numbers to continually grow until their carrying capacity, the number of animals that can be sustained by the available food supply, is reached.
In his research report, Hanan also concluded that more than mere deterrence measures are needed to address the Cove’s sea lion “issues.”
“I suggested (public) education and increasing signage,” the marine-mammal expert said. “A lot of foreign people come here who don’t know English. They don’t realize these are wild animals and are taking selfies next to them or posing their children on or near them for pictures.”
Concerning the prospects for success of any of the non-lethal deterrence methods he’s advocated, Hanan pointed out sea lions are intelligent and “persistent” creatures quick to adapt to changing circumstances. Asked his view on the notion of using “rolling cylinders” strategically placed at cliff access points to deter sea lions coming ashore, Hanan replied it was a good idea in principle. But he cautioned that many more cylinders may be needed than anticipated noting, “you’d be surprised how well sea lions can climb and get around obstacles.
“Some people are saying, ‘Just bang some pots and pans and they will run,'” said Hanan, while pointing out it’s not that easy. He added a variety of non-lethal deterrents have been used, to some degree of success, elsewhere along the West Coast. 
 “They work for awhile, but then the animals adapt and come back,” Hanan said.
Whatever deterrence method(s) are eventually chosen to deal with the Cove’s pinniped “explosion,” Hanan advises that more information is needed via research studies in order for the public and local government to make informed decisions on how best to deal with pinniped problems.
“We need to figure out (exactly) what they’re eating,” Hanan said, adding, for example, that in La Jolla, “They appear to be eating a lot of squid, when they’re in season, coming from the deep canyons.”
Hanan said the affects of El Niños and El Niñas, the cyclical warming and cooling of local ocean waters, also needs to be studied in much greater detail because temperature variation has a huge impact on how much – and what kind of – food is available to sustain La Jolla’a pinniped population.
It also might not be a bad idea to study the possibility of some pathogens, like bacteria, which, though relatively rare, can be transmitted from pinnipeds to humans through mutual contact with the marine environment he added.
“Fisherman have (historically) complained of ‘seal finger,’ a nasty bacteria that causes people’s joints to freeze up and hurt,” Hanan noted.
Hanan said he was uncertain what exactly will be done next with the information he has provided from his research study on the La Jolla pinniped population.