Rainbow Smelt, Osmerus mordax
Identifying characteristics: (Non-Native Fish) The Rainbow Smelt is a small slender member of the Osmeridae family. Similar to trout and salmon, Rainbow Smelt have a Dorsal fin and an adipose fin on the dorsum. Additional characteristics include teeth, as well as a long thin body with purple, pink and blue iridescent sides.
The Rainbow Smelt is native to North America's Atlantic coast from New Jersey to Labrador, and also occur naturally as landlocked populations in some lakes of New England and eastern Canada. In 1912, Rainbow Smelt were stocked in Crystal Lake, Michigan, and from there they made their way to Lake Michigan.
Similar to many migratory species, Rainbow Smelt ascend tributary streams to spawn over gravel. Their spawning period begins in the early spring (April), and extends for about a three-week period. Cool weather conditions may delay and/or extend the spawning period. Rainbow Smelt spawn at night and usually return to the lake by morning. At this time of year, people typically use dip-nets to capture (e.g., term; "Smelt-dipping) them from streams. The rest of the year, Rainbow Smelt school in lakes adjacent to cool, dark waters. Since Rainbow Smelt are sensitive to temperature and light, they keep to the mid-waters of the lake, and may descend to near bottom during bright daylight. A cool 45 degree F is their optimum water temperature.
Rainbow Smelt fry grow rapidly; in the Great Lakes most are mature by the end of two growing seasons, and nearly all will mature by the end of the third season. As with many other fish species, females grow faster and larger and live longer than males. Rainbow Smelt grow to an average size of 3 to 6inches in length in the Great Lakes.
Similar to species of the trout/salmon family, Rainbow Smelt feed on other living animals. Their diet includes aquatic invertebrates and other fish, including small Rainbow Smelt, sculpins, burbot and whitefish. In the Great Lakes, shrimp-like crustaceans are also a principal food items for Rainbow Smelt. Fish that prey on Rainbow Smelt include salmon, burbot, trout, walleye, yellow perch -- as well as other Rainbow Smelt!
For more information on how and where to catch Rainbow Smelt see our Michigan Fish and How to Catch Them and Better Fishing Waters.
Also see Rainbow Smelt Dipping and Fishing Opportunities for what you'll need to go Rainbow Smelt fishing and when to go Rainbow Smelt fishing.
Smelt graphic courtesy of Joseph R. Tomelleri and copyrighted.