1. By: Rosa Zamora & Maria Isabel Gonzalez 103
Rainbow Smelt
By: Rosa Zamora & Maria Isabel Gonzalez 103

2. PHYSICAL CHARACTERISTICS
Length: 7 to 9 inches
Weight: 3 ounces
Common names: smelt, American smelt, lee fish, freshwater smelt, frost fish
Coloring: silvery with pale green back; brilliant purple, blue and pink on sides
Slender bodies
Prefer dark cool waters
long pointed snout
mouth full of teeth
adipose fin
deeply forked caudal (tail) fin
smell exactly like cucumbers when freshly caught

3. DISTRIBUTION
Rainbow smelt were originally fishes of Eastern and Western North America, with most of the population occurring on the East coast between Labrador and New Jersey. On the Western coast of North America, Rainbow Smelt can be found as far south as Vancouver, and into the Alaskan Arctic Ocean to the North. Smelt occupy all North Atlantic waters and their tributaries.
Around the 1900’s some Rainbow Smelt from a freshwater lake in Maine were transported to Crystal Lake in Michigan to provide a food source for salmon and other large fish.
Rainbow smelt can be found today in lakes: Michigan, Huron, Ontario, Erie and Superior.

4. EFFECTS ON PEOPLE
When the Rainbow Smelt populations began to explode in inland lakes the numbers of many recreational sport fish began to decline. For those who seek these prized sport fish this was a terrible outcome when the original reason for transporting smelt in was to increase the population levels of the desired fish. However, a economic benefit did come from the situation. As the populations of Rainbow Smelt continued to increase, the numbers reached a high enough level to make commercial fishing for Smelt profitable. This along with an increased popularity of fishing for smelt has helped to control their numbers. Fishing can prove very effective either as winter time ice fishing, or more commonly during the spawning season when hundreds of thousands of Rainbow Smelt rush up lake tributaries to spawn. During these spawns many people will gather around streams with huge seines to pull in hundreds of the tasty fish.

5. EFFECTS ON ECOSYSTEM
Rainbow Smelt were originally introduced to inland lakes as a baitfish for sport fish such as Salmon Trout, and Walleye. However, this planned prey food source ended up becoming a predator. Smelt have damaged the large sport fish populations in two ways. First, the adult smelt prey on the young sport fish. This added source of predation has decreased the abundance of sport fish in many ecosystems. The other negative effect of Smelt is that that as young of year fish the smelt directly compete with the young sport fish for the limited supply of zooplankton. Rainbow Smelt populations that are found in inland lakes can have negative effects on the lake community. The smelt concentrates PCBs in its fatty tissue, and magnifies it through the food chain. High mercury levels also accumulate in the top food chain predators.  

6. SUCCESS
There is some evidence that the rate of mercury accumulation in top level fish consumers accelerates when they switch to a diet of smelt. Rainbow smelt are also rich in thiaminase, an enzyme that destroys thiamin, which is necessary for development of fish embryos; as lake trout and other sport fish consume the smelt, their ability to successfully reproduce diminishes because of thiamin-deficiency.

7. ISSUES FOR THE FUTURE
Current techniques can't eliminate smelt from lake communities without harming the rest of the lake population. For now the best way to deal with the problem is to reduce it through educational programming. The further spread of Rainbow Smelt and other exotics can be reduced, if not eliminated through aggressive educational programs that inform citizens of the hazards and negative effects that many exotics can have on an ecosystem. Tough state and federal laws that restrict the live transportation of exotics can also help in reducing their spread.

8. RAINBOW SMELT