In the lower Great Lakes, rainbow smelt were at first regarded as a nuisance, hordes of them invading and becoming entangled in fish nets. In Lake Superior, however, they were welcomed both as a forage fish and as a recreational target during their spring spawning runs. Systematic harvesting began in 1952, and dip-netting and seining in spawning streams has developed into a popular, seasonal sport. Spawns in spring, principally during darkness. Female can produce 12,000 to 50,000 eggs, which sink to the bottom and become attached to gravel substrate by a short stalk formed from the outer shell membrane.
Eggs hatch rapidly and larval young drift downstream to deep waters.
Sexual maturity attained at 2 years of age. This introduced species poses a potential threat to the fishes of our northern lakes.