BOSTON — Federal fishing regulators have changed the way they enforce laws and spend collected fines, officials said Monday, since a special investigation showed that fishermen in the Northeast were unfairly charged substantial fines for minor infractions and the money was used to buy items including international trips and a luxury boat.

The National Oceanic and Atmospheric Administration said it has centralized and increased control of its funds, made enforcement of laws more consistent with nationwide standards, and transferred the burden of proof of wrongdoing to enforcement officials.

“This administration conducted a top to bottom review and enacted sweeping reforms to ensure enforcement was fair and effective,” Eric Schwaab, an assistant administrator for NOAA, testified at a field hearing of the Senate Federal Financial Management Subcommittee at Faneuil Hall on Monday.

But for fishermen who have faced burdensome oversight and unfair fines, the changes aren’t enough.

“It is still hard for me to accept that unsupervised federal employees working in a rogue agency could be allowed to run amok in this nation,” said Lawrence Yacubian, a former scalloper in New Bedford.

The NOAA fined Yacubian $430,000 in fishing violations. It later returned money to him and 11 other fishermen after the investigation determined that their penalties were excessive or unjust. In total, the U.S. Commerce Secretary ordered the agency to return $650,000 in fines.

The agency also was criticized for what it bought with fines kept in its asset forfeiture fund, which now totals $7.5 million.

“The fines they seized from fishermen like me were lumped into one big account, from which staff bonuses, company cars, international staff travel and luxury boats were financed, with little to no oversight,” Yacubian told subcommittee chair Sen. Tom Carper, D-Del., and ranking member Sen. Scott Brown, R-Mass.

The senators reprimanded the agency for buying more than 200 vehicles for an enforcement staff of 172 and a luxury undercover boat worth $300,000, and paying for trips to Norway and Malaysia for conferences.

“These enforcement officials went on a spending spree funded by the hardworking fishermen,” Brown said. “They must account for the money paid by fishermen’s fines and ensure it is used properly.”

Under current law, the NOAA can use the asset forfeiture fund only for costs directly related to enforcement.

Schwaab said the agency’s comptroller now must approve all withdrawals over $1,000, many company credit cards have been seized, and an independent audit found the agency’s finances in good standing.