The center was notified shortly before 10 a.m. of a wounded sea lion at the harbor, center spokesman Jim Oswald said.
It appears the animal is the same sea lion crews had unsuccessfully attempted to rescue twice in the past week - once on Wednesday at Moss Landing Harbor and once on Friday night at Pier 39 in San Francisco, Oswald said.
A water rescue team responded to the dock today to try to rescue the sea lion, which has what appears to be fishing line tangled around its head and neck, Oswald said.
"This called for the water rescue team because we knew that the animal would immediately dive into the water," Oswald said.
Two rescuers with nets were in the water as a third rescuer slowly approached the animal from behind. Oswald explained that the rescuers in the water placed nets where the sea lion might dive, but that it managed to elude the volunteers four times.
The rescue efforts ceased at about 3:30 p.m., when the sea lion swam away.
"I think it got sick of people after all those attempts," Oswald said.
The sea lion appears to be dehydrated and malnourished, as its 300-pound weight is below what it should be, he said.
"We're poised to continue on the same rescue attempts tomorrow should this animal resurface," Oswald said.
On Wednesday, the rescue effort began at about 3 p.m. when the center received a call about a sea lion at the harbor, and sent out a team of about eight people to try to rescue it.
The crew got the sea lion to jump off the dock and into a net in the water, but the animal "had enough energy to jump out" of the net, Oswald said.