According to the Los Angeles County Fire Department, the two men were supposed to be picked up by a friend early Tuesday morning at the Cabrillo Marina but did not show up at the boat ramp.
Crews began a search at about 5:30 a.m. and found a boat up against the rocks near the 1800 block of Paseo Del Mar, but the men remain missing, the fire department said.
"We have nobody in the area of the debris field, so we have a number of resources, both land-based, out on the water in vessels, and also some drones as well to search the coastline," said LACoFD Captain Ocean Lifeguard Pono Barnes after the vessel was found.
The Coast Guard and the Long Beach Fire Department were also involved in the search. Due to extremely low fog, rescue crews weren't able to fly their helicopter. Officials said the hazardous conditions have not made the search easy.
"We got surf in the 6 to 10-foot range. There's a high surf advisory, so the area that they're fishing here was, there's some big surf out there today and the conditions are hazardous... It's a dangerous spot for sure," said Jake Miller, LACoFD Ocean Lifeguard Specialist Jake Miller.
The two men's names have not been released but authorities described them as being in their 50s.
Paseo Del Mar at Cloyden Road was closed as crews continued their investigation but has since reopened, according to authorities.
The search comes as authorities were warning the public to stay out of the water at Southland beaches due to large waves and dangerous rip currents.
A high surf advisory was issued by the National Weather Service until 9 p.m. Wednesday for Los Angeles County beaches and 4 p.m. Wednesday for Orange County. Forecasters said "large breaking waves" of 8 to 13 feet were impacting west-facing beaches Tuesday morning. Those waves were expected to back off to about 6 to 10 feet Tuesday afternoon, but that will still be enough to present a danger.
City News Service Inc. contributed to this report.