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Project title or topic of activity

Eat 'em and weep: Problems involving commercial fishing

Author(s): Mark Mergler, Dan Duncan, Heather Shive

Date: Spring 2000


Summary of Activity
50-100 words

Our project focuses on the impact of commercial fishing on the marine environment. Because humans rely on the sea as an important source of food and resources, they tend to overexploit its precious commodities. Many species of animals and plants are endangered due to the destructive nature of methods used for harvesting. Three major issues threatening marine species include over-fishing (catching more fish than can be reproduced), habitat destruction (destroying of the marine enviornment through human use), and by-catch (unwanted species of marine life that is caught). We intend to show how fishing practices create these problems and the effects that they have on fish populations. Through three different projects, we hope to help children better understand the negative effects of commercial fishing, raise their awareness of the need to conserve marine environments, and develop safer and better ways to obtain ocean resources.


Grade levels

Best suited for grades 5-6; ideal class size: 24-27; max: 30-33; min: 12.

General description or introduction
The scientific principles that the activity is founded on.

This project focuses on issues of human impact on the marine environment. It specifically investigates the problems associated with habitat destruction, by-catch, and overfishing. Through these three activites, students will examine how these practices impact fish populations and habitats.

Background information

Human impact on the marine environment extends to many areas and is frequently very detrimental. In particular, the fishing industry affects both target (wanted) and by-catch (non-wanted) species as well as threatening the stability of many habitats. By-catch includes any marine organisms which are inadvertently captured and/or killed through fishermen's activities. It can range from something as small as a snail to dolphins and porpoises. The proportion of by-catch species to target species is frequently as great as 100:1. The target species itself also suffers due to constant overfishing, which disallows the population to sustain its numbers through reproduction. Because populations are fished above their maximum sustainable yields (highest number fishermen can catch of one species without causing population desecration), they can be driven to extinction over time. Finally, habitat destruction occurs during fishing processes such as trawling (form of fishing where a net is dragged on the ocean bottom). Thus human impact extends far beyond the species that are targeted for consumption and threatens the entire marine ecosystem.

Credit for the activity

Two of the three activities are original ideas. The remaining activity focusing on overfishing was developed from a lesson plan in Janice VanCleave's book Oceans for Every Kid (Jon Wiley & Sons, Inc. 1996).

Estimated time to do the activity

These activities take approximately twenty minutes each for a total time of one hour.

Goals of Activity:

Goal A
Familiarize students with the idea of overfishing and its long-term effects on population sizes of various fish species

Goal B
Help students understand how fishing practices cause destruction to the marine environment

Goal C
Educate students about the problems involving by-catch and the harm it does to that are not targeted for the fishing industry

Goal D
{Goal D}


National Science Education Standards. (NSES)

Two content standards that this lesson plan covers:

Standard 1
Science as Inquiry: Content Standard A As a result of activities in grades 5-8, all students should develop abilities necessary to do scientific inquiry and understandings about scientific inquiry. These activities address standard A by developing students' abilities to follow scientific procedures. These activities will provoke further questions pertaining to conservation issues.

Standard 2
Life Science: Content Standard C As a result of activities in grades 5-8, all students should develop understanding of structure and function in living systems, reproduction and heredity, regulation and behavior, populations and ecosystems, and diversity and adaptions of organisms. Standard C is addressed through the comprehension of how overfishing affects commercial fish populations as well as by-catch populations. Additionally, the activity involving overfishing includes the subject of reproduction adn the impact humans have on population size. Ecosystems are addressed by the activity on habitat destruction.


Materials Needed

Overfishing Activity

  • dowel rods
  • rulers
  • dixie cups
  • Swedish fish (candy fish, app. 1-2 lbs.)
  • tape

Habitat Destruction Activity

  • fish
  • aquarium
  • plastic aquarium plants (50)
  • different colored jacks (20)
  • small fish nets
  • sanded/rocky bottom

By-catch Activity

  • various small-sized plastic fish
  • marine animals
  • large bucket
  • dixie cups


Engage: Prior to beginning the three conservation activities, have students list all the marine species that they consume. In small groups, allow them to brainstorm about the ways in which fishing could be harmful to the marine environment outside of these species.

Preparation: Prior to class, the instructor should collect the required materials and familiarize themselves with the goals and background information supplied for the activities. Also, it is recommended to set up each activity in different corners of the room to avoid congestion. Overfishing activity: collect all materials. Habitat destruction activity: set up tank with rock/sand and plants, set up jacks randomly in rocks, fill with water. By-catch activity: place fish in bucket.

Step-by-Step Procedure for the Activity

Activity 1: Overfishing
Each student should tape dowels to table and tape two dixie cups to ends of rulers Label one cup "consumption" and one cup "population" Ruler acts as balance on dowel rod Each student starts out with 20 fish Each student is allowed to choose however many fish they want in the consumption cup For remaining fish, multiply that number by growth rate number 1 (given by teacher)...this represents the number of offspring produced by remaining population Place new fish into "population" cup Compare to see if it is balanced Repeat with different growth rates

Activity 2: Habitat Destruction
Each jack is considered a target species and is worth 10 points Each student will get 2 minutes to grab as many jacks as possible with the fish nets Each plant knocked over is valued at -5 points Determine final scores

Activity 3: By-catch
Each student receives a cup A large bucket containing the fish is placed above the students' heads Bucket should contain 20% target species compared to number of bycatch Each student scoops out a cupful of plastic fish One specific fish (target fish) will be valued at 5 points The remaining species (by-catch) will be valued at -2 points Determine final scores

Images, work sheets, additional web pages


Items for discussion or conclusion

1st question

How does reproduction rate relate to maximum sustainable yield?

2nd question
Is it possible to obtain the target species without disturbing the environment?

3rd question
Is the number of target species caught worth the price paid for the amount of by-catch?

4th question
Are there better ways to obtain target species than the ones represented in the activities?


The students should be able to discuss the pros and cons that are associated with fishing practices. Understanding reproductive rate and maximum sustainable yield can be tested by quizzes on calculating population increases or decreases based on the reproductive rate.

Beyond the Activity
Further activities which relate to and extend the complexity of the experiment.

Students can brainstorm about less destructive methods for fishing and possible ways to prevent by-catch. Students can investigate which marine animals are endangered. Students can research the methods that are used to obtain their favorite types of seafood.

Web Resources
A web address with information on the topic of the activity.

Web Address

Additional References

Castro, Peter & Huber, Michael E. Marine Biology. McGraw-Hill, 2000.