Someone keeps stealing gongs and bells off buoys in Maine, and now the Coast Guard is offering a cash reward to find out who

US Coast Guard/Petty Officer 3rd Class MyeongHi Clegg

Coast Guard Cutter Willow's buoy-deck crew members install the clappers on a bell buoy before it is set in the water near Block Island, Rhode Island, September 6, 2013.

• Ten bells have been stolen from Coast Guard buoys along the coast of Maine since late 2017.
• The bells act as navigational aids, allowing mariners to find their way in times of low visibility.
• The Coast Guard thinks the bells, made of copper, are being resold and is offering a reward for information about the thefts.

Since late last year, thieves have taken 10 bells or gongs have been stolen from buoys floating off Maine's coast, and now the Coast Guard is offering a reward for information about the culprits.

Six buoys where hit during the first half of this year, and more have been swiped since then. The Coast Guard says nine bells were stolen from Penobscot Bay, and another one, the most recent, was stolen off Bailey Island in Harpswell.

The bells attached to the buoys are meant to help mariners navigate when visibility is low.

When the Coast Guard asked the public for information at the end of May, Lt. Matthew Odom, the waterways management division chief for the Coast Guard in northern New England, said the thefts "not only reduce the reliability of our aids-to-navigation system and put lives at risk, but they also create a burden and expense to the taxpayer for the buoy tenders and crews responsible for maintaining the aids."

US Coast Guard/Petty Officer 3rd Class William B. Mitchell

Seaman Cory J. Hoffman and Seaman Apprentice David A. Deere with a buoy on the deck of Coast Guard Cutter Bristol Bay in Lake Erie, November 12, 2007.

Each stolen bell has weighed 225 pounds, according to the Portland Press Herald. The gongs, like the one stolen from the White Bull Gong buoy off Bailey Island, weigh 371 pounds. The combined weight of the stolen gear is 2,755 pounds.

A Coast Guard spokesman told the Press Herald that the service has spent about $29,000 so far to replace bells and gongs that have been stolen. That doesn't include the time and labor that's been needed to fix and replace the equipment.

The Coast Guard says the bells are most likely being sold to nautical novelty stores or scrap yards. The service requires the bells be made of a copper-silicon alloy to resist corrosion and withstand the seawater to which they're constantly exposed.

The stolen merchandise could be worth a lot, depending on the market for copper. Silicon bronze, which is similar to the copper alloys used in the bells and gongs, can currently sell for about $1.50 a pound, according to a scrap-metal firm in Portland. Assuming all the bells and gongs can be sold, the 2,755-pound haul could net more than $4,100.

Tampering with navigation aids is a federal crime, punishable by fines up to $25,000 a day or a year in prison. The Coast Guard has asked those with information about the missing devices to call the Northern New England sector command center.

The reward for information that leads to an arrest and conviction can total up to half the amount of fines imposed.

The Associated Press contributed to this report.