What the Heck is an Otolith?

One of the many posts I have made about my fishing adventures on my Urban Fly Fishing DFW Facebook page was a photo of a freshwater drum (Aplodinotus grunniens) I had caught. This fish is known by many names, with a local favorite being “gaspergou” (GAS-per-goo), which is a corruption of the Cajun/Creole French casse-burgot, roughly meaning “mussel breaker.” Mussels and other mollusks comprise a substantial part of the freshwater drum’s diet, so the name makes perfect sense. If you speak Cajun/Creole French.

Of course, there was the normal discussion on the page about where I caught the beast, what fly did I use, are they hard fighters, are they good to eat, etc., but one guy chimed in out of left field with something along the lines of “Those are the fish with pearls in their head, right?”

Each fish has 3 pairs of otoliths, small, medium, and large. The largest are in the back of the head.
Photo by Greg DeMars


I literally cocked my head to one side and read it again. I had never heard of such a thing. Pearls in the head of a fish? I had to know more.

I was instantly on a Google quest, and searching for “freshwater drum head pearls” yielded some interesting results. These “head pearls” are actually bones in the head of the fish called otoliths that enable the fish to sense both direction and orientation in the water, and operate much like the bones of the inner ear in humans. In fact, the word otolith literally translates to “ear stone.”

As it turns out, the freshwater drum has some of the largest otoliths of all freshwater fish. Analysis of the structural and mineral content of these bones can tell us things such as the age of the fish and the climate and location in which the fish grew. Otoliths are also part of the fossil record dating back at least 150 million years. Present day, these relatively durable fish bones can be found along the edges of lakes and rivers inhabited by freshwater drum.

But the most interesting thing about otoliths (to me, at least) is their cultural history. These bones have been collected for millennia by Native Americans and used as good luck charms, currency, and jewelry. One of the colloquial expressions for these head pearls is “lucky stones.” Folklore suggests that carrying one or more of these lucky stones in your pocket, perhaps stitched into a small chamois leather or flannel pouch with coins, incense, pepper, perfume, or other items to increase their power, will imbue the holder with good luck. And according to this folklore, the people most likely to benefit from this good luck are job seekers, gamblers, businessmen, and prostitutes.

In keeping with the musical theme of Urban Fly Fishing Dallas–-Fort Worth, there’s even a song about lucky stones, recorded by blues legend Gertrude “Ma” Rainey in 1924 entitled Lucky Rock Blues.

Lucky Mojo Curio Company

Greg DeMars

Greg DeMars

Greg DeMars is a retired mechanical engineer who began his fly fishing adventures in the Colorado Rockies in the early 1990s and expanded his range from there, fishing all over the world. From the Devils River in his native Texas to New Zealand’s South Island and the foothills of the Indian Himalayas, Greg has pursued his passion for fly fishing with the analytical mind of an engineer and the creativity of a blues guitarist and songwriter, gaining valuable insight about fish behavior and fly fishing tactics along the way. An award-winning photographer, Greg ties his own flies and enjoys woodworking, cooking dinner for friends, and the occasional wee dram of fine Islay whisky. Greg is married to his college sweetheart and lives in the Dallas area. New blog posts covering insider tips and suggestions for fly fishing in the DFW area are published the 2nd Monday of each month.

2 thoughts to “What the Heck is an Otolith?”

  1. Can’t wait for the book. If you blog the answers to usual questions: where and what fly, if you don’t mind sharing, and I would really appreciate it if you could provide your thoughts on the safety of the location.

    1. Thanks for your comment, Kelly. All of the locations listed in the book are curated to be in relatively safe areas. Of course, being in a metropolitan area of more than 7 million people, there is no way to guarantee all locations will be safe, but we’ve done our best to avoid neighborhoods that might be less safe than others.

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