PORTLAND, Maine — A Portland man waived indictment and pleaded guilty Tuesday in U.S. District Court to illegally trafficking in elvers.

Yarann Im, 34, admitted to illegally catching, purchasing and selling about 480 pounds of elvers valued at more that $540,000 in 2013 and 2014.

Im is free on personal recognizance bail.

A sentencing date has not been set.

South Carolina and Maine are the only states that allow the commercial harvesting of elvers, which are juvenile American eels, and the industry is heavily regulated, according to court documents.

Florida has a commercial fishery for adult eels, through which fishermen may legally harvest elvers, but the eel’s migration patterns result in few elvers being harvested in the Sunshine State.

Elvers are worth many times more than adult eels when exported and sold to east Asian countries. Elvers fetched a record average price of $2,171 per pound in Maine in 2015.

In 2012, Im established Maine Eel Co. in Portland to purchase and sell American eels, according to the prosecution version of events to which he pleaded guilty. Early the following year, he got a license to harvest eels in Florida so he could conceal the origins of where the elvers actually were caught.

When and how investigators learned of Im’s activities has not been made public, but in 2014, on at least three occasions, he purchased elvers that had been harvested illegally from an undercover officer with the U.S. National Oceanic and Atmospheric Administration, which regulates the harvest and sale of elvers.

The court documents indicate that Im knowingly bought elvers that had been illegally harvested in Massachusetts, Virginia and North Carolina and falsely documented that they had been caught in South Carolina or Florida.

Im exported those elvers and others out of the country knowing they had been caught in violation of various state laws, according to the prosecution version of events to which he pleaded guilty.

Search warrants were executed on April 30, 2014, at Im’s elver storage and processing locations in Lowell, Massachusetts, and Providence, Rhode Island.

The case is being prosecuted by the environmental crimes section of the U.S. Department of Justice in Washington, D.C.

Im faces up to five years in federal prison and a fine of up to $100,000. He also could be ordered to forfeit equipment seized at the storage and processing locations.