Common River Fish of Missouri | Missouri's Natural Heritage

Anatomy

Fish body shapes vary wildly from genus to genus or even species to species, so there is no “archetypal” fish shape. Nevertheless, certain features remain constant across the majority of species. While not all species have both anterior and posterior dorsal fins, typically at least one is present for purposes of stability. Likewise, most fish have an organ known as the lateral line, commonly visible as a stripe running alongside the fish from the front to the rear. This organ is made up of a series of sensors known as neuromasts, which detect changes in the movement and pressure of the water around the fish. A fish’s lateral line allows it to detect obstacles, predators, and prey in even dark or murky water, and even fish without an obvious lateral line have neuromasts running along their length. Another key feature of many river fish is that the fish’s underside remains lighter than often dark or mottled top, a characteristic that aids with camouflage. Typically, darker tops allow fish to blend in with the substrate of a river or stream, while a lighter underbelly blends in with clouds and the sky when seen from below.

Specialities amongst the body types of different fish species reflect differences in lifestyle. Typically, larger predators like smallmouth bass are long and deep-bodied so as to remain hydrodynamic. Some fish, the gar family in particular, have extremely elongated bodies, with especially long jaws. The purpose of these long, toothy mandibles is similar to that of an oceanic swordfish or gavial crocodile: gar are fish eaters, and longer jaws allow for greater reach when striking prey. Catfish also have rather unique jaw characteristics, with long whiskers extrending from their chin and the ends of their lips. These whiskers are reflective of a catfish’s benthic lifestyle, helping them feel through murk and debris even by night with great dexterity in search of prey.

Game Fish

The term “game fish” is a general be-all and end-all term for any fish species pursued for sport, and by no means dictates what can or cannot be caught on a rod and reel. On the whole, game fish are characterized more by the fight they put up when hooked than any other characteristic, and are frequently large, predatory fish. The Missouri Department of Conservation differentiates these species from the rest by imposing regulations on when and from where certain fish can be caught, as well as by setting limits on how many can be harvested rather than released. Most species of bass are considered game fish, such as smallmouth bass, largemouth bass, rock bass, and more. Many catifish are game fish as well, such as blue and channel catfish. Trout too are game fish, although unlike the rest of Missouri’s listed game fish, both rainbow and brown trout are non-native, introduced from Asia and raised in hatcheries for sport. Other game fish include paddlefish, Missouri’s state aquatic animal, bowfin, muskellunge, pike, walleye, sauger, and more. To fish in Missouri, anglers between the ages of 15 and 65 require a state-issuable permit.

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Due to harvesting by man as well as environmental threats such as pollution, many species of game fish find their populations under stress. Male largemouth and especially smallmouth bass have recently been observed with female attributes, such as eggs, in certain Missouri river systems. These changes are thought to be caused by endocrine disruptors, synthetic hormones released into waterways by pollution from birth control products and livestock hormones. Threats like this have the potential to wreak havoc on native fish populations, and for this reason facilities such as the Lost Valley Hatchery exist to restock the state’s waters with certain species of game fish as needed.

Invasives

Not all commonly seen fish in Missouri rivers are native, or beneficial. Missouri rivers house four species of invasive Asian carp, the grass carp, silver carp, bighead carp, and common carp. These large, deep-bodied fish all grow to as large as four feet in length, and are voracious eaters, devouring small organisms and plant life with few natural predators to inhibit their feeding. Entire river ecosystems can be destroyed as these invasive fish eat the smaller species out of the food chain. Moreover, these fish are a threat to human health, as any loud sounds or vibrations in the water cause them to jump out of the water with power belied by their bulk. In heavily populated river systems, a single motorboat can send hundreds of fish flying through the air, threatening damage to both people and property. Conservation efforts for these species can be difficult because of the degree to which they are already established, but the Missouri Department of Conservation urges anglers to catch and eat invasive carp species, a possibly effective solution seeing as how they are considered a delicacy in certain party of Asia.

Longear Sunfish

Found in rivers and lakes of all sizes throughout Southern Missouri, the longear sunfish is no game fish, but is still commonly caught by anglers on rod and reel. These brightly colored panfish, related to the more widely-known bluegill, prefer clear, shallow water, where they can make their circular nests amidst the sand and gravel of the substrate. During this breeding period, stretching from late spring to the early summer, longear sunfish attack a variety of small baits aggressively. Their diets naturally consist of small invertebrates as well as the eggs and young of other fish, or even smaller sunfish.

Longnose Gar

The majority of Missouri’s larger rivers and streams house longnose gar, as well as some large lakes. Gar can frequently be found floating near the surface, although they are active hunters of fish. Although not a game fish, the longnose gar is still sought after by some anglers, albeit through a different fashion than most other fish. Gar’s long snouts and jagged teeth, as well as their diet of other fish, renders many conventional baits and lures useless, so fishermen instead resort to unventional lures consisting of yarn or strings, which wrap around the fish’s snout when struck and can be easily cut away with no harm to the fish. Gar breed in groups during the spring and summer, with a high male to femal ratio, and prefer shallow to open water.

Blue Catfish

Missouri’s largest catfish, blue catfish are most prevalent in Missouri’s large rivers, such as the Mississippi and Missouri, where they scour the murky depths for fish and crustaceans with the help of their whiskers. Touch and smell are very important to blue catfish, as they hunt in dark, turbid waters and are very active at night, so anglers often use smelly baits to attract them: these fish are game fish. Despite their preference for deep, dark water, blue catfish breed in burrows formed in the shallows along riverbanks, or under logs or rocks, where they guard their eggs viciously. This characteristic spawning behavior has given rise to another form of fishing known as noodling, which involves sticking one’s hand into a breeding burrow to lure the fish into biting one’s hand directly, allowing the angler to pull the fish out by hand. Noodling is both very effective and very dangerous to the catfish, as without their parent, blue catfish eggs suffer very high mortality to predators and fungus. Missouri thus deems such fishing illegal.

Rainbow Trout

A cold water species (preferring waters below 70 degrees farenheit), rainbow trout are found only in Ozark lakes and streams. Missouri has some self-sustaining populations, but the rest are managed by the controlled release of trout from hatcheries along rivers like the Meramec, as this is a much sought-after game fish. Rainbow trout eat small fish and invertebrates, but due to their large reliance on insects and snails that fall into waterways as food, fly-fishing for them is common, and many anglers use lightweight baits called flies that float atop the surface to induce strikes. Tradiitional rod-and-reel fishing works as well, with corn being a surprisingly effective substitute. Breeding occurs in the midst of winter, from December to February, but most Missouri populations are restocked artificially.

Smallmouth Bass

One of Missouri’s most popular game fish, smallmouth bass can be found throughout the Ozarks in rivers and streams, as well as the upper Mississippi River and its tributaries. A large, fast predator, these fish play the same ecological role as their cousings the spotted and largemouth basses in the ecosystems they call home, where they feed on any small prey they can get their mouths on. Like most other bass, smallmouths are game fish, biting at a varitey of baits, from worms to spinnerbaits to crayfish and more. They often make nests in the pebbles of the shallows along the main current of the streams they call home. Despite issues with endocrine disruptors and other pollutants, these fish remain prevalent throughout much of their historical range.

Silver Carp

Common in large rivers and lakes, these fish are non-native to Missouri and problematic. They consume vast quanities of algae and other plant life from the river bottom, and in waters where they are introduced often cause problems for the food chain, as well as people. Due to their non-carnivorous diet, traditional fishing methods vary, and can be quite difficult. Breeding requires a rise in river level, as a large rain would cause, so lake populations tend to not be self-sustaining. An invasive species, the artificial transfer of silver carp, as well as its relatives from Asia, is illegal.