PIKES AND MUDMINNOWS: Esociformes

PHYSICAL CHARACTERISTICS

A striking characteristic of pikes, a group that includes muskellunge, and mudminnows is that the dorsal (DOOR-suhl) fin, the fin along the midline of the back, is quite far back on the body. The bodies of pikes and mudminnows are not tapered at the ends and are round in cross section. Some of these fishes have a long, flat snout. Although most pikes and mudminnows are small or medium-sized, the largest pikes can reach more than 5 feet (1.5 meters) in length and weigh more than 66 pounds (30 kilograms). The smallest mudminnow rarely reaches 4 inches (10 centimeters) in length and weighs less than 1 ounce (28 grams). The colors of pikes and mudminnows vary, but markings or mottled patterns on a brown or olive green background are common.

GEOGRAPHIC RANGE

Pikes and mudminnows live all over the Northern Hemisphere except Greenland.

HABITAT

Adult pikes move freely between shore and open water. All pikes and mudminnows prefer still or slow-moving water where dense plants give them a place to hide. Other than dense plant cover, mudminnows seek areas with a thick and loose muddy bottom, into which they quickly dive when startled. The digestive tract, the body parts that change food into energy, and the swim bladder, an internal sac used to control position in the water, of mudminnows are modified to extract oxygen from gulped air. This feature allows the fish to withstand the high oxygen levels of water heavy with plants.

DIET

All pikes eat fishes, including smaller fish of their own species. Larger pikes also may eat frogs, water birds, and small mammals. Mudminnows eat invertebrates (in-VER-teh-brehts), or animals without a backbone, and, very rarely, young fish.

BEHAVIOR AND REPRODUCTION

Outside the breeding season, pikes and mudminnows are solitary and swim and live alone. Pikes usually hover among plants and use small fin movements to stay in place. From this position, the fish wait for their prey, or animals hunted and killed for food, which they capture with a fast strike. Mudminnows may perch on plants or rest on the bottom, eliminating the need for fin movement. When oxygen levels in the water are low, mudminnows swim up to the water surface and gulp air.

Most pikes and mudminnows spawn, or release eggs, early in the spring when water temperatures begin to increase. Some migrate to reach their spawning grounds. Spawning most often involves one female and a few to several males. In some species, the males court the females through swimming displays or aggression. Before releasing eggs, the fish make exaggerated swimming motions and side-to-side contact. Eggs may stick to plants or drop to the bottom. The young do not receive parental care.

PIKES AND MUDMINNOWS AND PEOPLE

Pikes are popular sport fishes. Mudminnows are used for bait in some areas. Some people keep them in aquariums.

CONSERVATION STATUS

The World Conservation Union (IUCN) lists one species of pikes and minnows as Vulnerable, or facing high risk of extinction in the wild, and one as Lower Risk/Near Threatened, or at risk of becoming threatened with extinction in the future.

MUSKELLUNGE (Esox masquinongy): SPECIES ACCOUNT

Physical characteristics: Most muskellunge weigh 7 to 20 pounds (3 to 9 kg). The highest weight recorded is about 70 pounds (31.8 kilograms), and that fish was 6 feet (1.8 meters) long. The usual length is less than 40 inches (1 meter). The body is silver or light green with dark spots or mottled markings, but the color varies according to habitat, and markings may be absent. The cheeks and the gill covering have scales on only the upper half. Muskellunge have large pores on the lower jaw.

Geographic range: Muskellunge live in North America in the Great Lakes region.

Habitat: Muskellunge live in slow-moving or still waters with dense plant life.

Diet: Muskellunge are greedy predators (PREH-duh-ters), or animals that hunt and kill other animals for food. They feed mainly on fish but also eat crayfish, frogs, water birds, and small mammals. The young eat small invertebrates until they are able to capture larger animals.

Behavior and reproduction: Muskellunge hover among water plants, striking at prey with a fast, powerful movement. They sometimes float just beneath the water surface with their backs exposed to the air. Muskellunge spawn in spring. Males and females move close to shore or from streams to marshy areas. One female and a few smaller males swim into shallow, heavily planted areas. Females release a small number of eggs, onto which the males immediately deposit sperm. Egg release is repeated a varying number of times. Both males and females may spawn with different mates during a spawning season. Adults do not guard spawning sites or provide care to the young. Muskellunge and northern pike can breed with each other, and if they do, they produce tiger muskies, a hybrid that cannot produce its own young. Therefore, muskellunge avoid areas where northern pike spawn by releasing eggs in deeper water.

Muskellunge and people: Muskellunge are popular sport fish.

Conservation status: Muskellunge are not threatened or endangered. ∎

FOR MORE INFORMATION

Books:

Berra, Tim M. Freshwater Fish Distribution. San Diego, CA: Academic Press, 2001.

Gilbert, Carter Rowell, and James D. Williams. National Audubon Society Field Guide to Fishes: North America. New York: Knopf, 2002.

Schultz, Ken. Ken Schultz's Field Guide to Freshwater Fish. New York: Wiley, 2004.

Web sites:

Paulson, Nicole, and Jay T. Hatch. "Central Mudminnow: Umbra Limi (Kirtland, 1840)." University of Minnesota. http://www.gen.umn.edu/research/fish/fishes/central_mudminnow.html (accessed on September 26, 2004).

"Understanding Northern Pike and Muskie." The Content Well. http://www.thecontentwell.com/Fish_Game/Northern_Pike/Pike_index.html (accessed on September 26, 2004).

"What Is a Muskie? The Basics." International Muskie Home Page. http://www.trentu.ca/muskie/biology/biol01.html (accessed on September 26, 2004).