SOURCE Lesson Plans Detail

Marine Ecosystems and Overfishing

Topic Marine Biology
Program Brown Science Prep
Developed by Elizabeth Pon, Jonathan Sit, Anna Delamerced
Developer Type High school students

Lesson Motivation

If current trends continue, world food fisheries could collapse entirely by 2050. This lesson is intended to inform students about the reality of overfishing and the ways in which it could affect our environment.

Lesson Activities

"Go Fish" - students will learn about overfishing by playing a game in which they are fishers attempting to catch enough fish to stay in business. At the end of the game, students will analyze how their consumerism has affected the ocean's sustainability.

Procedure

Introduction:
What resources do you use from the ocean?

  • food (seaweed, fish, shellfish, lobster, sushi)
  • oil reserves (vehicle gasoline)
  • recreation (vacation, swimming)
Did you know?
  • About 50-80% of all life on earth is found under the ocean surface, and the oceans contain 99% of the living space on the planet.
  • We have explored less than 5% of the ocean.
  • 1 in 5 people depends on fish as the primary source of protein.
  • Air pollution is responsible for 33% of the toxic contaminants that end up in oceans and coastal waters.
  • If current trends continue, world food fisheries could collapse entirely by 2050.

Intro to Food Chains & Webs
  • Ask: What is a food chain? A food web?
    • Where do you think we, as humans, fall within a marine ecosystem food chain?
  • **Make it interactive: Ask students to brainstorm living things in the ocean. Write these on the chalkboard. Have 1 or more students come to the board to draw a food web (with the rest of the class’s help).
    • Arrows point from prey to predator

Food Chains & Webs
  • A food chain is a group of organisms linked in order of the food they eat, from producers to consumers, and from prey, predators, scavengers, and decomposers.
  • A food web shows all related food chains in an ecosystem. It is also called a food cycle.

What’s in a food web?
  • An autotroph, also known as a producer, is an organism on the food chain that can produce its own energy and nutrients.
  • A heterotroph, or consumer, is an organism that is unable to make its own nutrients and must feed on organic material present in other organisms, living or dead.

Let’s look at a marine environment--the Arctic Ocean:
  • Phytoplankton and algae/kelp/seaweed would be an example of primary producers or autotrophs.They use photosynthesis to produce their own food using energy from the sun.
  • Primary consumers like zooplankton and krill are small organisms that eat these primary producers.
  • Fish like cod or herring, or even small animals like penguins are examples of secondary consumers.
  • Some tertiary consumers are giant squid and leopard seals. Like the other consumers, they’re heterotrophs, too!
  • Quaternary Consumers like killer whales and great white sharks are at the top of the food chain. Species at the top with no predators of its own are also called apex predators (or alpha or top predators).

Can you draw a food web among these animals? Hint: arrows point to the consumer. (use animals for the web including seal, killer whale, penguin, squid, cod, krill, plankton).


Part 2: Conservation/Sustainability of the Marine Ecosystem

Activity: “Go Fish”

Materials:
  • Craisins
  • Goldfish
  • M&Ms
  • Swedish fish
  • Tape
  • Paper plates
  • Napkins (1 per student)
  • Straws (2 per student)

The gist:
You’ll spend 4 years fishing in your ocean for Craisin Fish, Goldfish, M&M Fish, and Swedish Fish. Each “year” you’ll have 30 seconds to fish for as many fish as you can using the straws and tape and your poles and hooks. Each fish has a different monetary value, and you each must catch a minimum dollar amount of fish in order to stay in business the following year. After, the fish left in the ocean have a chance to reproduce--but they need at least two per species and their food source (see food web!) in order to do so.

*Note to mentors: It’s probably best to put the “ocean” on the lab table in the front of the room, and position kids around it.
*Don’t have fewer than 3 people per plate. You can play too!
*If 30 seconds per round is not enough, adjust as needed!

Details:
  • ~4 fisherpersons per ocean (a paper plate). You cannot touch, tip, or move the ocean.
  • Each fisherperson gets 2 fishing poles (straws) and a net (4 inches tape). No fishing with hands is allowed! Each person gets a boat (napkin) onto which she should place her caught fish. Fish that fall out of the boat onto the table do not count.
  • You will fish in your ocean for 4 years. Every year, you will have 30 seconds to fish.
  • There are 4 different species in the ocean. Each has a different market value.
    • Craisin Fish: $2
    • Goldfish: $3
    • M&M Fish: $5
    • Swedish Fish: $10
  • You must earn at least $5/year to stay in business. But we live in a capitalistic society, so you want to earn as much money as possible.
  • At the end of each year, the fish have a chance to reproduce. For every 2 fish of that species, they will make 2 baby fish. [Fish mate in pairs; single fish don’t reproduce.]
  • The fish are part of a food web and need to have food to survive.
    • Craisin Fish eat seaweed. There’s plenty of seaweed in the ocean so they’re fine.
    • Goldfish and M&M Fish eat Craisin Fish. There must be at least 1 Craisin Fish in the ocean for these fish to survive.
    • Swedish Fish eat both Goldfish and M&M Fish; there must be at least 1 Goldfish and 1 M&M Fish in the ocean for Swedish Fish to survive.
  • Your ocean will start off with:
    • 4 Craisins
    • 4 Goldfish
    • 4 M&Ms
    • 4 Swedish Fish
  • You have 30 seconds to fish. You must put down your fishing pole when time is up.
  • Fill out your data table, tracking the number of each species of fish that remains in the ocean, the number and monetary value of your catch, and the income earned by each fisherperson in your group. Once you’ve filled out the tables, you may eat your catch.
  • The number of fish in the ocean will be adjusted according to the rules of the food web and reproduction.
  • Fish for another 3 years, pausing to record data and adjust fish after each year.
  • With your group, calculate the number of different fish caught and the final number of fish left in the ocean.

Overview / Purpose / Essential Questions

  • What is a marine food web?
  • What is overfishing, and why is it pertinent?

Performance / Lesson Objective(s)

  • What is a marine food web?
  • What is overfishing, and why is it pertinent?

Lesson Materials

  • Craisins
  • Goldfish
  • M&Ms
  • Swedish fish
  • Tape
  • Paper plates
  • Napkins (1 per student)
  • Straws (2 per student)


 

Wrap up / Conclusion

Discussion:

  • What happened over the years?
    1. got too zealous and depleted the fish supply! mess with the food web too.
  • Was one fish more popular than another?
    1. hopefully, yes. also depends on how easy one is to catch over another. did students want goldfish because they like to eat them more than craisins? think about popular fish--like salmon & tuna--how does desiring one fish over another affect the rest of the ecosystem?
  • How does this model demonstrate what is happening to our oceans?
    1. overfishing; strain on food webs/ecosystems, etc.
  • What might we do to prevent our oceans from being overfished?
    1. quotas, international laws, conservation efforts--no fishing zones

Follow up

Students should relate overfishing to the "go fish" game and discuss how to preserve environmental stability while still eating seafood.

Supporting Web Information

Reference(s)

See the links above.

Pre Assessment Plan

 

A heterotroph, or consumer, is an organism that is unable to make its own nutrients and must feed on organic material present in other organisms, living or dead.

A food web shows all related food chains in an ecosystem. It is also called a food cycle.

The oceans yield about 2% of the world’s food.

True or False: If current trends continue, there won’t be enough fish by 2050.

What is sustainability?

Underlined terms are the answers to the questions.

Post Assessment Plan

Students should review the answers to the pre-assessment questions.

Supplies List

QtyUnitItem
1RollTape
1PackagePlastic plates
1PackageStraws

Alignment Info

Audience(s) High school students
STEM Area(s) Environmental Sciences
Standard(s)
Life Sciences (RI GSE) LS2.EXT.3a
Students demonstrate an understanding of equilibrium in an ecosystem by …
Activity Type(s) Hands-on
Grade Level(s) High School
Version 1
Created 11/11/2012 01:43 PM
Updated 12/20/2018 11:54 AM