On the rural crime of ... something related to fish bait

The headline out of the Grand Forks Herald yesterday was, "'It's a witch hunt': Federal agents raid Minn. bait shop, seize thousands of baitfish."  Having read the entire story, I'm not at all clear what the possible crime is, though it appears to be linked to the provenance of the bait.  Here's the lede:  

U.S. Fish and Wildlife Service agents raided the Great Outdoors Bait Shop in Ely on Dec. 1, seizing more than 6,000 ciscoes along with the shop's computer files, tax records and banking records, said Jim Maki, the shop's owner.

Ciscoes, a baitfish popular with winter anglers, are typically netted each fall near Prairie Portage on Basswood Lake, in the Boundary Waters Canoe Area Wilderness on the U.S.-Canadian border east of Ely. 

Maki said that eight to 10 special agents with the U.S. Fish and Wildlife Service entered his shop that day, asking him repeated questions about whether the ciscoes he sells came from the U.S. or Canadian side of the international border.

Maki, who has run the bait shop for 34 years, is quoted responsible for the "It's a witch hunt" quote.  He explained that the ciscoes are used to fish for northern pike and lake trout, and sell for $9/dozen.

That's the big-money thing for the winter.  I'm shot now for the winter if I don't get the ciscoes back.

That said, Maki explained that he might buy smelt if he can't get his ciscoes back.