The tired old joke goes like this: “How can you tell the difference between a partridge and a grouse?” You know the answer, right? If it’s shot on the ground, it’s a partridge; if it is shot on the wing, it is a grouse.

Well, now there is a new twist along the language line that has arisen from the piscatorial realm. It is doubtful that you have yet heard of this one, which has been created by a new baitfish regulation. The question for you — and it’s not a trick — is this: When is an Emerald Shiner not an Emerald Shiner? The answer is, according to the new fishing regulations, when it is an Eastern Silvery Minnow.

Stay with me.

As most veteran Maine ice anglers know, the Emerald Shiner, next to a rainbow Smelt, is a highly popular ice-fishing bait. Since Emerald Shiners are not native to Maine, and since it is highly illegal to use non-native baitfish through the ice, you might wonder: how did we get away with it all these years?

All of these ice fisherman and apparently many Maine bait dealers thought that they were buying and selling Emerald Shiners when, in fact, they were selling and using Eastern Silvery Minnows or Common Shiners.

Yes, it was a case of mistaken identity or simply wishful thinking on the part of ice anglers who had heard of the Emerald Shiner’s reputation as a baitfish in other states.

It gets more confounding, especially if you are a person who does not do well with ambiguity. The 2017 fishing law book lists as legal live bait both Emerald Shiners and Eastern Silvery Minnows. Since the bait dealers have long been selling Eastern Silvery Minnows as “Emeralds,” will they continue to do so, or will they change their marketing strategy to accommodate the new Emerald Shiner ban?

The Department, in its announcement, acknowledges the difficulty in distinguishing between the true Emerald Shiner and the Eastern Silvery Minnow: “These species can be challenging to distinguish from one another. Especially when comparing Emerald Shiners and Eastern Silvery Minnows, confirmation often comes down to using a microscope to count the number of scales along the lateral line, counting anal fin rays, and determining if the mouth is crescent-shaped or U-shaped.”

The takeaway message for the average hard-water angler is not to worry. If you buy your winter live bait from a reputable bait dealer, you should be OK no matter what name he attaches to those wiggly little “shiners” that you buy by the dozen.

In the fishing law book there is a list of 18 baitfish that are legal in Maine. This must have always been a challenging enforcement issue for game wardens who check ice fishermen. With the new ban on Emerald Shiners, it just got a little more so.

The author is editor of the “Northwoods Sporting Journal.” He is also a Maine guide and host of a weekly radio program — “Maine Outdoors” — heard Sundays at 7 p.m. on “The Voice of Maine News – Talk Network.” He has authored three books; online purchase information is available at www.maineoutdoorpublications.com.