REGIONAL REPORT : Warm Ocean Brings Vivid Change to Marine System : Environment: Fishermen and surfers bask in the friendly waters, while scientists study the phenomenon.

A marine biologist diving near Santa Catalina Island was startled to find an unfamiliar off-white-colored starfish usually indigenous to the tropical waters of South America.

Near Point Loma in San Diego, the waters are providing a unique harvest of such exotic species as yellowfin tuna and dorado, prompting commercial fisherman Lance Withee to say he has “never seen the ocean like this before.”

And for surfers at Newport Beach, swimming trunks often replace the full-body wet suit, normally de rigueur as Southern California moves into the winter.

Warmer-than-average ocean temperatures off Southern California--as much as 10 degrees above normal on a given day--are intriguing scientists, fascinating fishermen and delighting surfers from Santa Barbara to Mexico.

Researchers at the Scripps Institution of Oceanography in La Jolla say monthly average temperatures since June have topped normal temperatures by as much as five degrees. The highest readings occurred in July.

“We’re really excited about it,” said Orange Coast College marine biologist Dennis Kelly, who has heard reports of unusual sea turtles and other warm-water creatures as close as four miles to Newport Pier. “It opens up a lot of doors for us for research.”

No one is quite sure why the tropical-like waters have pushed ocean temperatures up. And scientists are less willing to predict what the trend could mean for the future.

“It’s a big ocean out there,” said biological oceanographer John McGowan, a member of the Scripps Climate Research Division. “There is so much going on that we just can’t see.”

Some specialists suggest a shift in wind patterns may be the cause. Others point to a change in an ocean current. Still others are concerned that the warm water may be a harbinger of El Nino, a Pacific Ocean weather pattern that causes severe drought in some areas of the Pacific Rim and devastating storms in others.

Southern California has experienced a slackening of strong westerly winds, which normally blow across the ocean and churn the deeper, colder water. The resulting “upwelling” cools the shallower warm water.

Without the wind, the upper layer of ocean water becomes tepid--an explanation offered by Newport Beach Marine Safety officer Gordon C. Reed.

“We’ve had little wind to speak of this year,” he said.

But others suggest that the warming is the result of an errant current that is also dragging to the Southern California coastline an array of exotic marine life.

Marine biologist Jeff Landsman, with the Cabrillo Marine Museum in San Pedro, said that he and other researchers have noted unusual ocean life that seems to be associated with the warm water. Thousands of South American Humboldt squid were beached near San Onofre in the summer, he said.

Another striking example was the discovery of the starfish, a Tamaria obstipa , off Catalina by Landsman’s colleague, Lloyd Ellis. The creature is native to coastal waters off Peru.

Finds like that have prompted Landsman and other scientists to conclude that the warmer-than-normal water might be the result of an off-season flow of the Davidson Countercurrent, which pushes water northward from Baja California in February.

“There’s too much out there to believe that it’s just the lack of winds,” Landsman said. “I don’t believe that it’s upwelling that is causing this.”

Whatever the reason, the tropical-like waters have been a boon to such beachgoers as 19-year-old Jason Smith, an avid Newport Beach surfer.

On a recent day his wet suit lay unused nearby.

“You don’t even need the suit,” said his 18-year-old friend, Rip Arenz. “Yeah, the water is really warm. I don’t know why.”

And sportfishermen are enjoying the bounty. Withee, who owns and operates the Vagabond, an 80-foot sportfishing boat out of Point Loma, said he has caught tropical fish without having to travel hundreds of miles south.

“It’s never before been like this,” Withee said. “We’ve had a long bite of exotic species out there.”

Withee and other fishermen say that dorado are normally caught during a two-week period in August. But since May, they have been bringing on board hundreds of the iridescent, blue-and-green fish each day. Fishermen also report higher than normal concentrations of yellowtail tuna.

Zeke Grader, executive director for the Sausalito-based Pacific Coast Federation of Fishermen’s Associations, said the catches are helping the $1.5-billion commercial fishing industry as well as sports fishermen.

But Grader said that if the unseasonably warm temperatures continue, important colder-water fish may be driven away. For example, experts say a small squid that spawns off Santa Catalina Island in the winter would be threatened by the warmer water.

“It’s hard to say whether we are looking at something unusual,” Grader said, “but we’re watching very carefully the water conditions.”

Grader said that the last time warm water hurt the fishing industry was in 1982-83, when a strong El Nino--the worst such weather system in the century--devastated the salmon harvest.

Scripps researchers said that fears of an impending El Nino are ill-placed.

Nick Graham, part of a team studying the phenomenon, said the earliest an El Nino could form would be next year.

Scripps’ McGowan also said the warm waters do not appear to be a sign that an El Nino is beginning.

Absent are other signs of the phenomenon--called the El Nino-Southern Oscillation, or ENSO--which are found in the equatorial and eastern Pacific regions.

For an El Nino to take place, Graham said, barometric pressure in the area of Darwin, Australia, must rise and pressure over Tahiti must fall. Neither condition has occurred.

In addition, El Nino is associated with increased rainfall in the central equatorial Pacific, elevated sea surface temperatures from South America to the international date line and weaker easterly winds along the Equator, Graham said.

“We don’t have all the (other) danger signals yet,” McGowan said. “They are just not all in place.”