Hands-on Activity: All Caught Up

Contributed by: Engineering K-PhD Program, Pratt School of Engineering, Duke University

Photograph shows a gray fish in a string net.
Students learn the issues surrounding bycatch
Copyright © 2004 Microsoft Corporation, One Microsoft Way, Redmond, WA 98052-6399 USA. All rights reserved. http://office.microsoft.com/en-us/images/results.aspx?qu=fishing+net&ex=1#ai:MP900387435|mt:2|


Commercial fishing nets often trap "unprofitable" animals in the process of catching target species. In this activity, students experience the difficulty that fishermen experience while trying to isolate a target species when a variety of sea animals are found in the area of interest. Then the class discusses the large magnitude of this problem. Students practice data acquisition and analysis skills by collecting data and processing it to deduce trends on target species distribution. They conclude by discussing how bycatch impacts their lives and whether or not it is an important environmental issue that needs attention. As an extension, students use their creativity and innovative skills to design nets or other methods, theoretically and/or through hands-on prototyping, that fisherman could use to help avoid bycatch.
This engineering curriculum meets Next Generation Science Standards (NGSS).

Engineering Connection

Through the activitry extension, students imagine and design technological solutions for addressing the problem of bycatch by making design changes to the nets they use in the activity.

Pre-Req Knowledge

Knowledge of data collection, calculating fractions/proportions, analyzing data.

Learning Objectives

  • Students will be able to explain the basics of bycatching and what species are most affected by it.
  • Students will question the importance of environmental activism with regard to bycatching, relating it to their daily lives.

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Educational Standards

Each TeachEngineering lesson or activity is correlated to one or more K-12 science, technology, engineering or math (STEM) educational standards.

All 100,000+ K-12 STEM standards covered in TeachEngineering are collected, maintained and packaged by the Achievement Standards Network (ASN), a project of D2L (www.achievementstandards.org).

In the ASN, standards are hierarchically structured: first by source; e.g., by state; within source by type; e.g., science or mathematics; within type by subtype, then by grade, etc.

  • Define a simple design problem reflecting a need or a want that includes specified criteria for success and constraints on materials, time, or cost. (Grades 3 - 5) Details... View more aligned curriculum... Do you agree with this alignment?
  • Use decimal notation for fractions with denominators 10 or 100. (Grade 4) Details... View more aligned curriculum... Do you agree with this alignment?
  • Fluently add, subtract, multiply, and divide multi-digit decimals using the standard algorithm for each operation. (Grade 6) Details... View more aligned curriculum... Do you agree with this alignment?
  • Various relationships exist between technology and other fields of study. (Grades 3 - 5) Details... View more aligned curriculum... Do you agree with this alignment?
  • The use of technology can have unintended consequences. (Grades 3 - 5) Details... View more aligned curriculum... Do you agree with this alignment?
  • The use of technology affects the environment in good and bad ways. (Grades 3 - 5) Details... View more aligned curriculum... Do you agree with this alignment?
  • Identify and collect information about everyday problems that can be solved by technology, and generate ideas and requirements for solving a problem. (Grades 3 - 5) Details... View more aligned curriculum... Do you agree with this alignment?
  • Investigate and assess the influence of a specific technology on the individual, family, community, and environment. (Grades 3 - 5) Details... View more aligned curriculum... Do you agree with this alignment?
  • Examine the trade-offs of using a product or system and decide when it could be used. (Grades 3 - 5) Details... View more aligned curriculum... Do you agree with this alignment?
  • Decisions to develop and use technologies often put environmental and economic concerns in direct competition with one another. (Grades 6 - 8) Details... View more aligned curriculum... Do you agree with this alignment?
  • Design is a creative planning process that leads to useful products and systems. (Grades 6 - 8) Details... View more aligned curriculum... Do you agree with this alignment?
  • Brainstorming is a group problem-solving design process in which each person in the group presents his or her ideas in an open forum. (Grades 6 - 8) Details... View more aligned curriculum... Do you agree with this alignment?
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Materials List

Each group needs:

  • larger bucket/container
  • smaller container
  • blindfold
  • "fishing net" (provide an assortment, such as cups, mesh bags, sandwich bags or aquarium fishing nets)
  • an assortment of many marbles and other balls of different colors and sizes, placed in a bowl to prevent them from rolling around; cheaper materials can be used, such as rocks; while numbers/colors/types of balls (fish) are flexible, here is an example assortment: 5 large red rubber balls (like the type for playing jacks), 10 glass marbles of color A, 10 glass marbles of color B, 3 golf balls, 4 pairs of dice, 10 very small pebbles (much smaller than the marbles)
  • water
  • paper and pencils, for recording data


The issue of bycatching has many different points-of-view. Three of the main perspectives are: fishermen who are trying to make a living, bycatched dolphins and turtles that innocently lose their lives as a casualty of the economic market, and the average consumer who wants to be able to buy seafood at an affordable price.

Today you will get the chance to experience a simulation of what it is like to be a commercial fisherman and experience some of the problems related to bycatch.


Before the Activity

  • Fill each group's larger bucket or container about three-quarters full with water.
  • Add a good variety of different marbles or balls to the water in each container.
  • Pick one of the marble types to be the "target fish." The rest are potential bycatch species. As an example, from the example ball list in the Materials List, the five large rubber balls would be a good target species because they are medium-sized relative to the other balls, leving the remainder of the other balls well sized to represent larger and smaller "species," with the potential to become bycatch, depending on the "fishing net" used.

With the Students

Divide the class into groups of four students each. Direct each student in every team to complete the following procedure:

  1. Choose a type of fishing net to use.
  2. Have your group members add the remaining marbles and balls to the water.
  3. Have your teammates blindfold you.
  4. Attempt to fish for the "target fish." Use the net to make two sweeps (make sure everyone is consistent), emptying your net into the group's smaller container.
  5. Remove the blindfold.
  6. Make a table to record your data: Initial number of total balls in the bucket and Number of balls removed during fishing. Within the number of balls removed, tally the exact number of each type of ball removed (for example, 5 small red balls, 2 large purple balls). After each student in the class completes this activity, each group of four will have four tables of numbers.
  7. Then, each group combines its members' data in order to calculate different percentages, which might include: 1) percentage of "target fish" in the initial full bucket (number of total "target fish" divided by number of total fish) versus the percentage of "target fish" that comprised the total number of fished balls (number of target fish obtained in the net divided by the total number of balls obtained fishing) or 2) percentage of "target fish" caught (number of "target fish" caught divided by the total number of "target fish") versus the percentage of other fish that were caught.
  8. Lead a class discussion to analyze results, as described in the Assessment section. Ask the Investigating Questions.
  9. Conduct the lesson extension to have students design (and perhaps prototype and test) innovative fishing nets as solutions to bycatching, as described in the Assessment and Lesson Extension sections.

Safety Issues

  • Watch that students are careful with the hard marbles and golf balls; they should not be thrown at people or left on the floor.

Troubleshooting Tips

If students have trouble discriminating the types of balls, encourage them to use their different senses when using the net. Make sure that students do not place their fingers into the bucket; they should use their senses only through the net itself. For example, they should be able to feel the difference in resistence between large heavy balls and small light balls while fishing with the net.

Investigating Questions

  • Do you think bycatching affects your life? Do you think it is an important issue?
  • Did you find it easy or hard to just catch the "target species"? Why or why not?
  • Which types of gathering devices worked the best, and why?
  • What types of results did you get, in reference to your calculations? Were you surprised by your results? Did your teammates get similar or different results? Why?
  • Can you think of ways of designing a net that could be more effective? Are there any other materials you wish you could have tried? What are they and why do you think they would work better?
  • Are there any other methods you think would be successful in reducing bycatch besides modifications in fishing gear design?


Pre-Activity Assessment

Perspectives: Following the bycatch-related lesson, Caught in the Net, make sure that students understand the basic principles of bycatching—why it happens and what species are most affected by it. Encourage students to discuss their opinions on bycatching—whether it is something fisherman should try to avoid/minimize or whether it is an acceptable loss of animal life.

Activity Embedded Assessment

Analysis Questions: By calculating the fractions/percentages of different populations caught and thus the distributions of the fish caught versus the original distribution in the buckets, students analyze whether their fishing techniques are 100% foolproof or whether there is little to no discrimination between the "target species" and the non-target species. Encourage students to think about ways to improve the efficiency of these nets, and thus reduce bycatch. Ask them the Investigative Questions to get them to thoroughly analyze their data and reflect on their experiences.

Post-Activity Assessment

Design Solutions: Have students conduct the activity extension to design nets that help to reduce bycatch by allowing certain species to escape while retaining the target species. This could be done hypothetically by brainstorming and drawing design ideas, or taking it further and prototyping with real materials. Expect students to be impressed and satisfied with their own abilities and achievement in synthesizing the problems and proposing potential solutions surrounding bycatching.

Activity Extensions

  • For older students, incorporate a design element to the activity by having groups design innovative fishing nets that could be used to help eliminate bycatching. Use the example of dolphin bycatching in tuna fishing nets, or turtle bycatching in fishing nets. Start by having teams brainstorm ideas and sketch concepts for net designs that avoid bycatching large balls while still catching smaller balls (as designated in the activity). Take it further by providing materials from which they can create and test prototype nets.
  • For students of all ages, especially younger ones, conduct the following exercise to help them experience firsthand the difficulty of escaping from entanglement. Have each student loop a rubber band around his or her thumb and fourth finger. Then, have them try to remove the rubber band from their fingers without using their other free hand. See http://www.vims.edu/bridge for more information on this activity.


"Bycatch." http://www.bdmlr.org.uk/news/bycatch.html

"Estimated Annual Pinniped Bycatch by Species and United Nations Food and Agriculture Organization (FAO) Area." http://www.imma.org/seallist.html

"Marine Conservation." http://environet.policy.net/marine/issue/

"Net Loss: Fishery Bycatch." http://www.biology.duke.edu/bio217/fish/bycatch.html

"Ocean Sciences Teacher Resources." http://www.vims.edu/bridge

"Sea Turtles Bycatch." http://www.seaturtles.org/images/photoarchive/photos/ACF65.JPG


Aruna Venkatesan, Pratt School of Engineering; Matt Nusnbaum, Pratt School of Engineering; Angela Jiang, Pratt School of Engineering; Vicki Thayer, Nicholas School of the Environment; Amy Whitt, Nicholas School of the Environment


© 2013 by Regents of the University of Colorado; original © 2004 Duke University

Supporting Program

Engineering K-PhD Program, Pratt School of Engineering, Duke University


This content was developed by the MUSIC (Math Understanding through Science Integrated with Curriculum) Program in the Pratt School of Engineering at Duke University under National Science Foundation GK-12 grant no. DGE 0338262. However, these contents do not necessarily represent the policies of the NSF, and you should not assume endorsement by the federal government.

Last modified: August 10, 2017