Get all the details on the species known as freshwater drum
As common as gaspergou are in Louisiana and the United States, few people realize how unique this freshwater species really is. Virtually any waters that connect with the Mississippi, Pearl and Mobile river systems and all the Great Lakes except Lake Superior are home to the species — 27 states. The species has also been introduced by man into states as far-flung as California and Massachusetts.
To the south, the fish is found through eastern Mexico into Rio Usumacinta in Guatemala.
In short, the fish is nearly everywhere in North America.
Louisiana seems to be the heart of the beast’s range. It is the only state in the Union in which every square foot is listed as being home to gaspergou. It is common in lakes, reservoirs, bayous, and rivers. It reaches peak abundance in the large, turbid waters of the Mississippi, Red, and Atchafalaya rivers. Probably the only place it isn’t common is in small, clear, swiftly flowing, sandy-bottomed headwater streams.
Gou are an odd fish
Gaspergou, or “gou,” as we more often call it, is a Louisiana name. More properly, the species is known as the freshwater drum.
It is a unique fish for a bunch of reasons. It is the only member of the drum family found totally in freshwater. Some, such as redfish, can penetrate deeply into freshwater and thrive there much of their lives, but they can’t spawn there. They have to go back to their saltwater roots to do that.
Another interesting characteristic of the fish is that they possess a tapetum lucidum in each eye, a feature easy to see in the light of a camera’s flash or a flashlight at night. A tapetum lucidum is a layer of cells behind the retina of the eye that gathers light and reflects it back through the retina.
Tapeta lucida provide superior night vision to animals that are active in low-light conditions or at night. Found in wolves (and dogs), all species of cats, deer, rabbits and many other creatures, it is absent in daylight-loving creatures such as humans and birds.
It is uncommon in fish, with the best known exceptions being the walleye and the much less noted gaspergou. In both species their eyes shine brightly. In gou, the feature may have evolved to allow the fish to see better in the 50 to 60-foot depths of muddy rivers.
Gou are also unique in possessing “lucky bones.” These are actually otoliths or ear bones and all fish possess a pair. Located behind and above each eye, they float loosely inside the inner ear of the fish and help it maintain its balance. Without them, a fish could not remain upright.
What is unique about them in gaspergou is their size. They are huge. A 12- to 14-inch fish will have otoliths nearly as large as a nickel. They are extremely hard and look almost polished and ivory-like. They are so hard that they don’t even break down in the digestive system of another fish that eats a gou.
In the Great Lakes and other places with hard beaches, these durable otoliths often wash up on shore. They received their nickname of lucky bones because the otolith from the right side of the fish has a very noticeable L-shaped groove in it. (The one on the left side is more J-shaped.)
Grow slow: grow big
Gaspergou are not a particularly fast-growing species, reaching 4.4 to 5.8 inches at the end of their first year. Gaspergou can reach 12 inches in length (the minimum legal commercial size in Louisiana) as early as 3 years in the South and as late as 5 years in the northerly waters of the Great Lakes.
By 10 years old, gou may only be 17 inches long and weigh a little over 2 pounds in the Great Lakes, but 24 to 28 inches long in the South, where the growing season is longer. Females grow faster than males after age 4.
Gaspergou grow large. The world record is 54 pounds, 8 ounces, and was caught from Nickajack Lake in Tennessee in 1972. They can also live to be very old. A 72-year-old fish from Red Lake, Minnesota was aged. Thirty-two-year old fish have been aged from the Cahaba River in Alabama.
Gou are easy to catch because they eat everything
Because gaspergou have large crushing teeth in their throats, it was long assumed that their primary diet was clams and mussels. Research now indicates that adults feed more heavily upon immature aquatic insects, crawfish and fish.
Some times of the year, fish, especially shad, can make up more than 90 percent of their diet. Also eaten are shiners, young bluegill and crappie, and bullhead catfish, as well as other species, including quite a few of their own kind. Some clams and other mollusks are also eaten.
A Lake Pontchartrain study done in 1961 showed gaspergou as major consumers of mud crabs, small blue crabs and rangia clams.
Take a gou home for dinner
Gaspergou are commonly caught by Louisiana fishermen and are excellent table fare if prepared right (Hint: Don’t fry them.) They must however be handled properly. They die quickly out of water, even on a stringer or in a live basket.
Gou should be iced immediately after being caught. Their flesh has a high fat content and upon death, the fat oxidizes rapidly, especially in hot weather. Poorly handled gou quickly develop a “fishy” flavor.