LOS ANGELES — The Coast Guard signaled Wednesday that it would undertake a series of recommended safety reforms for passenger vessels in the wake of a 2019 scuba dive boat fire that killed 34 people off the California coast, but a top transportation official cautioned that any changes might take years to enact.

The blaze broke out aboard the Conception during the final night of a three-day Labor Day weekend scuba diving excursion near Santa Cruz Island off Santa Barbara. The tragedy marked the deadliest marine disaster in California in modern history.

In December, Congress mandated that the Coast Guard review its regulations for small passenger vessels. The law, included in the National Defense Authorization Act, also added new requirements regarding fire detection and suppression.

In a letter dated Wednesday, Coast Guard Vice Admiral Scott Buschman said he agreed with seven recommendations suggested by the National Transportation Safety Board after the Conception tragedy. The recommendations include installing more comprehensive smoke detector systems, requiring safety management systems, upgrading emergency exists and making mandatory inspection checks on roving watches.

The victims' families have pushed for such reforms, banding together to form "Advocacy34" to pressure officials to move forward to prevent tragedies.

It's not clear when the recommendations could be put in place. Coast Guard officials did not respond Thursday to a request for comment. Buschman's letter was first reported by the Los Angeles Times.

While investigators said they couldn't determine what caused the fire because the boat burned and sank, they say it started toward the back of the main deck salon, where divers had plugged in phones, flashlights and other items with combustible lithium ion batteries. After the fire, the Coast Guard issued a bulletin recommending a limit on the unsupervised use of lithium ion batteries and extensive use of power strips and extension cords.

In October, the NTSB blamed the Conception's owners for a lack of oversight and the boat's captain for failing to post a roving night watchman aboard the vessel, which allowed the fire to quickly spread and trap the 33 passengers and one crew member below deck. Captain Jerry Boylan and four crew members, all of whom were sleeping above deck, escaped.

Coast Guard records also showed that since 1991, no owner, operator or charterer has been issued a citation or fine for failure to post a roving patrol, prompting the NTSB to fault the Coast Guard for not enforcing that requirement and recommend it develop a program to ensure boats with overnight passengers actually have the watchman.

The NTSB has no regulatory or enforcement power, and can only suggest nonbinding recommendations to the Coast Guard and the Federal Aviation Administration, which previously have routinely ignored the agency's suggestions.

NTSB Chairman Robert Sumwalt told The Associated Press that while the safety board appreciated the Coast Guard's response, "what really matters is their follow-up action."

"They might concur with something that we're saying but pushing it over the finish line becomes a very slow process," he said.

Sumwalt said even though Congress has authorized it, the recommendations still have to go through several layers of bureaucracy before they can become requirements.

The Conception's captain, Jerry Boylan, is scheduled to appear in federal court Tuesday to face 34 counts of seaman's manslaughter for "misconduct, negligence and inattention" by failing to train his crew, conduct fire drills and post a roving night watchman on the Conception when the fire broke out Sept. 2, 2019.

The boat's owners, Truth Aquatics Inc., have not been charged criminally.