Activity: Predicting Smelt Runs

Summary: Once the warm weather starts to hit in the spring, rivers and streams that connect to the Great Lakes are dotted with flashlights and fishermen holding buckets and nets through the night. They’re trying to capitalize on rainbow smelt spawning runs. With a little know-how and understanding on smelt spawning behavior, the runs can be predicted with some certainty. In this activity, students will use USGS water data to predict smelt runs.

You Need:


As a whole class:

  • Find the Salmon Trout River in Michigan’s Upper Peninsula on a map of the Great Lakes region.
  • Explore the region.
  • Which direction does the river flow? Into which Great Lake does the river flow?
  • Identify nearby towns.

Working in small groups:

Explore water temperature and discharge data from the Salmon Trout River. Students should use USGS water temperature and discharge data to:

  • Graph water temperature and discharge data from April and May 2006-2008. Each student creates at least one graph, 12 graphs per group.
  • Answer questions using data and graphs.
  • Communicate conclusions (questions 3-5 on data sheet) to the class using water temperature and discharge graphs as evidence.

Activity Extension

Investigate other locations where smelt spawn.

  • List of locations from Michigan Department of Natural Resources and Environment (DNRE). Smelt Dipping Opportunities: Streams and Great Lakes Shoreline (PDF).
  • U.S. Geological Survey: Real-Time Data for Michigan
    • Select link to the right of the station name to access historical data

Photoperiod is another factor influencing smelt spawning. Ask students to determine how to incorporate photo period into their predictions.

  • U.S. Naval Oceanography: sun or moon rise/set for one year

Species other than smelt spawn in Great Lakes tributaries.

  • Ask students to research which other species spawn in tributaries and where they spawn.