Starting today, fishing will be halted or limited in some 15 percent of Southern California's most bountiful ocean waters under a new landmark environmental protection initiative.

From Point Conception in Santa Barbara County south to the Mexico border, more than 350 square miles of open sea will become state marine protected areas. These underwater parks, the result of a long-running planning process that often pitted fishermen against environmentalists in a passionate tug-of-war, are meant to protect crucial marine habitat and boost fish stocks.

Los Angeles County will see two marine protected areas on the edges of Santa Monica Bay: off Point Dume in Malibu and off Point Vicente and Abalone Cove on the Palos Verdes Peninsula.

"It's hugely important," said Sarah Sikich, coastal resources director with the environmental advocacy group Heal the Bay. "We're very excited that the MPAs that have been worked on so deeply over the past several years in Southern California are finally taking effect."

But many fishermen aren't so excited.

Joel Greenberg, chairman of the Southern California chapter of the Recreational Fishing Alliance, said there's broad reaction among recreational and commercial fisherman to the new MPAs.

"There's everything from `Oh, my bacon didn't get fried' to real misery because their best fishing grounds appear to be closed for perpetuity," Greenberg said.

Greenberg, a Valley Village resident and longtime fisherman, maintains that despite dozens of public meetings, the process in the end was "top down" - meaning the closures were imposed by state officials despite the outcry of many fishermen.

Sikich and Greenberg were among 60-plus stakeholders who began meeting in 2008 to debate, draw and redraw boundaries of proposed closure areas as part of the implementation of a 1999 law called the Marine Life Protection Act. Meetings of a committee overseeing the process sometimes drew more than 1,000 attendees.

In December 2010, the state Fish and Game Commission approved boundaries for MPAs in the South Coast region, the third of five regions along the state's 1,100-mile coastline to undergo the process. Densely populated and heavily used, the Southern California coast proved especially contentious.

The final decision, approved on a split vote and billed as a compromise between fishing and environmental groups, left some unsatisfied. Overall, 37 new protected areas were established, extending to the edge of state waters, 3 miles from the coastline.

Battles were intense over Rocky Point in Palos Verdes, a prime fishing spot that has some of the most pristine habitat in Southern California, and over Point Dume, where a submarine canyon and kelp reef provide a fish nursery and rich waters for anglers.

Ultimately, Rocky Point was left open while a less productive area off the peninsula will be protected.

About 15 square miles off Point Vicente will be closed to fishing; an adjacent 5 square-mile conservation area at Abalone Cove will allow some spearfishing and take of squid, as well as some commercial fishing.

Part of Point Dume's kelp reef was also kept open to fishing, while spearfishing and commercial take of some species will be allowed in an adjacent conservation area that's nearly 16 square miles. Fishing will be completely banned - including take of seaweed from the shore - in a reserve of about 7.5 square miles.

Greenberg questioned whether the state would create a "poacher's haven" by creating additional responsibilities for fish and wildlife wardens without providing new funding and resources.

Jordan Traverso, a spokeswoman for the Department of Fish and Game, said there are 75 wildlife officers in Southern California, along with three large patrol boats and fleet of skiffs. Patrols are deployed to best protect state resources, she said.

Beginning today, enforcement is at the discretion of wardens and can range from a warning to arrest, depending on the situation, she said. Fishermen, she said, are generally "self-regulating."

Witnesses to poaching or polluting are encouraged to call the department's confidential tip line at 888-DFG-CALTIP.

"We've done our best with outreach," Traverso said. "I'm sure that there will be different challenges. I don't think we have any expectations of things that can't be overcome through education."

Funding for wildlife enforcement in Gov. Jerry Brown's 2012 budget will be unveiled in coming weeks.

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