PORTLAND, Maine: Fishermen in the US's only commercial-scale fishing industry for valuable baby eels, called elvers, have recorded a productive season searching for the tiny fish, which are often worth more than $2,000 per pound due to demand from Asian aquaculture companies.

The fish are raised to maturity so they can be served in Japanese food, some of which is sold in the US at Japanese restaurants.

The Maine Department of Marine Resources said the elvers are being sold for more than $2,000 per pound this year, and fishermen are limited to a combined quota of under 10,000 pounds per year, having nearly reached their limit by early May.

Jeffrey K. Pierce, a former Maine state representative and adviser to the Maine Elver Fishermen Association, said that this year, fishermen have been helped by favorable weather and strong international demand.

Maine eels have become more valuable in recent years, as international sources of baby eels have mostly run out.

"There is a huge demand for it. They are not getting a lot out of Europe. And it's just a great product," Pierce said.

South Carolina is the only other US state with a fishing industry that catch baby eels, but its fishery is much smaller than Maine's.

Because of their value, the global eel industry has been threatened by poaching for many years, and federal law enforcement has targeted illegal eel fishing.

However, the illegal trade still continues. A study by a research team led by the University of Exeter, published this year, found that some 40 percent of North American unagi samples they tested contained European eels, which are banned from being imported and exported.