(US Coast Guard photo by Petty Officer 3rd Class MyeongHi Clegg)

Since late 2017, thieves have taken 10 bells or gongs 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 2018, 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 2018, 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."

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, Nov. 12, 2007.

(US Coast Guard photo by Petty Officer 3rd Class William B. Mitchell)

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 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 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.

This article originally appeared on Business Insider. Follow @BusinessInsider on Twitter.