Featured Lesson

Lesson 4:2 - Fish Surveys

by Roland Sigurdson

February 2009

Some fish surveys utilize fish tags.

Chapter 4 of the Fishing: Get in the Habitat! lesson series contains five of the 39 lessons. All of us use natural resources and share the responsibility for ensuring a sustainable quality of life in our state. This chapter identifies how the Minnesota Department of Natural Resources and the citizens of Minnesota work together to manage and conserve our natural resources through role-playing and problem solving activities. This is a big job and a serious responsibility in which we all must play a part.

Lesson 4:2 - Fish Surveys is a great lesson that connects fish sampling techniques, mathematics and natural resource management with real world outcomes.

Lesson Summary

This lesson will help students learn why and how fisheries managers conduct fish surveys. Students will become familiar with some of the equipment and survey methods that Minnesota DNR fisheries biologists use. Special authorization, equipment, and expertise are needed to conduct a fish population survey in an actual lake, but you can conduct a survey simulation with student participation. Using tagging survey techniques and a formula involving multiplication and division, students estimate the number of walleye in an aquarium representing a lake. They conduct a problem solving investigation that helps them determine why local anglers are catching fewer fish in Lake MinnAqua.

Tips & Tricks

• There are seven parts to the Procedure in this lesson, so become familiar with the complete lesson ahead of time. While you may never have calculated a Capture-Mark-Recapture study before, the lesson unfolds in a thoughtful, well-planned way to make it easy for the students to grasp the objectives.
• This lesson is very interdisciplinary. Connecting with your math curriculum will assist students in finding real world uses for estimates, ratios, and proportions. This is the ultimate 'hands on' word problem!
• Spend a bit of time on the Wrap-up. One of the things that should become apparent to students is that in all sampling there is a certain amount of error. Discuss how being inconsistent in your sampling technique might skew the results of your hard work.
• Invite a fisheries biologist to visit your classroom or find out if the Area Fisheries Office will be sampling near your location. You may be able to observe a fisheries crew in action!
Some fish surveys utilize fish clips.

Diving Deeper

For those students that are doubtful about the accuracy of this method, consider using suggestion #1 under Diving Deeper. Students will determine the percent error in order to find out how well their results mimic the real population size.

MinnAqua Lesson Connections

The concept of Carrying Capacity can be difficult one for students to grasp. Consider using Lesson 1:2 – Food Chain Tag or Lesson 1:3 – Run For Your Life Cycle as a way to help students connect the number of fish that can survive in any given lake with the available habitat and food resource available to those fish.