Overfishing and Aquaculture
6 - 8
Students will discover the sources of various fish and seafood, compare wild-caught and farm-raised aquaculture systems, and use a simulation to learn how overfishing can damage the ocean ecosystem. Grades 6-8
Two 1-hour class periods
- Comparing Aquaculture handout, 1 per student
- Internet access and projection ability for video clips:
- The Lifespan of Overfishing Student Data Table, 1 per student
- Large box of colored Goldfish® crackers
- Per group of 4 students:
- 1 paper plate
- 4 napkins/paper towels
- 4 spoons
- 4 pieces of string
- 4 straws
- Access to tape
- Public Awareness Campaign Rubric
- Poster paper, 1 per group
Essential Files (maps, charts, pictures, or documents)
aquaculture: the cultivation of aquatic organisms (such as fish or shellfish) especially for food
bivalve mollusk: aquatic mollusk whose body is enclosed in a hinged shell such as oysters, clams, mussels, and scallops
crustacean: a type of animal (such as a crab or lobster) that has several pairs of legs and a body made up of sections that are covered in a hard, outer shell
fish farm: a place where fish are artificially bred or cultivated for food, restocking lakes for angling, or to supply aquariums
mollusk: a type of invertebrate animal (such as snails, clams, or squids) that has a soft body, does not have a backbone, and usually lives in a shell
overfishing: to fish to the detriment of a fishing ground or to the depletion of a kind of organism
seafood: shellfish and sea fish served as food
sustainability: a method of harvesting or using resources so that they are not depleted and/or permanently damaged
wild-caught: taken from the wild rather than being bred from domestic stock
Did You Know? (Ag Facts)
- Shrimp is the #1 consumed seafood in the United States. Canned tuna and salmon are second and third.1
- In the United States the term seafood refers to all edible aquatic life and can include both salt-water and fresh-water species.2
- Seafood is a nutrient-dense source of dietary protein that is relatively low in calories and saturated fat compared to some other protein sources.3
- USDA's MyPlate dietary guidelines recommend two servings of seafood per week.3
Background Agricultural Connections
Seafood (fish and shellfish) are a nutrient-dense source of dietary protein. Compared to other sources of protein, seafood is low in calories and saturated fat and rich in key nutrients including zinc, magnesium, phosphorous, potassium, and vitamins A, B12, and D. Seafood is also a primary food source of omega-3 fatty acids, EPA, and DHA.3 The American Heart Association and the Dietary Guidelines for Americans recommends eating two, 3.5 ounce servings of fish per week.4
The seafood we purchase at retail markets can come from a variety of sources. Aquaculture is the farming of aquatic organisms such as fish, crustaceans, mollusks, and aquatic plants. Fish-farming can involve raising fish commercially in tanks or other man-made enclosures such as ponds or concrete fish runs. These farms manage their water (flow, oxygen levels, etc.) and the growth of fish from the fertilization of eggs until harvest. Other fish farms follow similar principles, but use a cage system in a natural water source such as a lake or ocean. These farms use the same water and habitat as wild fish, but keep their fish in separate enclosures. Regardless of the type of system, it is considered a farm if humans manage the breeding, feeding, and growth of the fish. In the United States, trout and catfish are the most commonly farmed fish species. World-wide, the seafood most commonly farmed are shrimp and salmon.5
Some of the seafood we eat is supplied through fishing. This seafood is usually labeled as wild-caught and is harvested using nets, trawls, or other devices. Wild harvest commercial fishermen work closely with government agencies to help ensure that wild stocks are not overfished in US waters. The National Marine Fisheries Service identifies areas considered essential to living marine resources and regulates the use of these areas so that the habitats remain healthy, sustainable, and productive. Although many waters are managed through quotas on the number of fish that can be caught and restrictions on the size of fish that can be harvested, the breeding, feeding, and growth of the fish are not managed by humans in any way.
Many species of fish and shellfish can be raised on farms or caught from the wild. The dietary value of fish resulting from both (farmed or wild-caught) production methods is equal. In addition to a dietary comparison, a look at the environmental impacts of each system is critical to maintaining the long-term sustainability of fish farming and wild-caught fisheries. It is estimated that wild-caught fisheries have reached their maximum sustainable yield, while the world's appetite for seafood is growing.6
One solution to this challenge is the aquaculture industry, which can satisfy the growing demand for seafood in an environmentally friendly and sustainable manner. US aquaculture operations raise fish such as trout, tilapia, barramundi, and cobia that can replace more familiar species on menus yet still meet customers' wants and needs. Other farms are raising traditional marine species such as cod, flounder, and halibut. The availability of these species from farms allows consumers to access their favorite seafood while wild fish stocks recover.
Another example of aquaculture providing positive environmental impacts is the production of bivalve mollusks, such as clams, oysters, and mollusks. These shellfish remove nutrients from the water by feeding on algae and particulate matter. This helps maintain good water quality and minimizes the loss of critical oxygen. While farmed shellfish are growing, they spawn and help to reseed wild shellfish beds. Due to their unique structure, bivalve mollusks provide habitats and hiding places for other organisms, adding to the biodiversity of the marine ecosystem. These impacts are so important that, in some areas, community volunteers are restoring oyster and clam populations.
Interest Approach - Engagement
- Tell your students to imagine they are walking through the grocery story in the meat department and they come across the seafood section. Ask, "What kind of meat do you expect to be here?" (Students may list any seafood item they are familiar with such as shrimp, crab, lobster, and various fish such as salmon, trout, haddock, halibut, etc.)
- Ask students, "Where did this meat come from?" As they offer answers, guide them to the question, "Did it come from a farm?"
- Continue the discussion by asking if there is a difference between fishing and farming. Some specific questions to guide your discussion might be What is farming?, What is fishing?, How are fishing and farming different/the same?, Is the fish you eat from a farm or from the ocean?
- Share the Did You Know? Ag Facts listed in the lesson. Clarify the definition of seafood and inform students that in this lesson they will be learning about a variety of seafood including fish, shellfish, and crustaceans.
Activity 1: Sourcing Fish and Seafood
- Ask students if they can guess how long fish has been part of our diets in human history. Show the Harvesting Knowledge- Fish Farming video clip from America's Heartland to answer the question. After the video, ask students, "How do we get these fish from the water to our plates?"
- Give each student one copy of the Comparing Aquaculture handout. Using the back side of the handout as a guide, describe three different methods of harvesting fish and seafood for human consumption.
- Inform students that they will be taking a video tour of the three different methods. As they watch each video clip, they should fill out the Venn diagram noting the differences and similarities found while comparing each system.
- Note: If students are not familiar with Venn diagrams, give additional instructions describing what each portion of the circle represents.
- Show the following video clips:
- After watching the videos, have a class discussion to summarize what students learned. Point out to students that not all the lobsters we eat are wild-caught and not all oysters and catfish are farmed. Lobsters can be farm-raised and oysters and catfish can be wild-caught. Use the following questions to help guide their comparisons and complete their Venn diagrams:
- Where do the fish/seafood shown in the videos live? (lobsters and oysters live in natural waters, catfish live in man-made waters)
- Where do the fish/seafood shown in the videos get their food? (lobsters eat from the ocean, oysters and catfish are fed by farmers)
- Which method is regulated by what type of animals can be harvested? (Wild-caught fishing. In order to manage the populations of wild lobsters, fishermen must follow specific requirements to maintain a healthy population of lobsters and protect other species.)
- Which method has the potential for harming other populations of animals? (Wild-caught fishing. The fishing process could inadvertently harvest or harm other species. You can also note that in some cases invasive species can be better managed to improve the ecosystem through fishing practices.)
- Which fish/seafood shown in the videos were completely reliant upon farmers to manage breeding, feeding, and growth? (oysters and catfish)
- Which method has the goal of producing a food product for human consumption? (all three)
- Which method strives for sustainability? (all three)
Activity 2: The Lifespan of Overfishing
- Now that students have a basic knowledge of a few methods used to produce and harvest fish and seafood, inform them that this activity will focus on an ecological issue with wild-caught fish.
- Review the basic concepts of a food web. Give examples if needed to help students recall that a food web is a system of interlocking and interdependent food chains. Ask students to give examples of food chains and webs that can be found in an ocean.
- Introduce the activity by telling students that they will be simulating an ocean food web using colored goldfish crackers. Explain that in this ocean’s food web the plain yellow goldfish eat seaweed of which there is always plenty, the green goldfish and red goldfish eat the yellow goldfish, and the dark orange goldfish eat both green goldfish and red goldfish.
- Note that there must be at least two goldfish in the ocean for these fish to survive. However, you may or may not want to share this with the students immediately.
- Inform the students that in addition to its place in the food web, each fish also has a dollar value, and the purpose is to earn money. If the fish are harvested, each yellow goldfish will make a profit of $2, red goldfish will make a profit of $5 each, green goldfish will make a profit of $5 each, and dark orange goldfish will make a profit of $10 each.
- Organize students into groups of four. Give each student one copy of The Lifespan of Overfishing Student Data Table. Have one person from each group collect the following supplies:
- 1 plate
- 4 spoons
- 4 straws
- 4 napkins
- 4 pieces of string
- 1 roll of tape
- At the start of the activity, put 8-10 of each color of goldfish into each group's ocean (paper plate). (Numbers can be adjusted as the teacher sees fit.) Have the students record the number of each fish in the "Year 1 Start" column of their data table.
- When all the oceans are stocked and fishing poles are made, give the students 30 seconds to fish. At the stopping signal, all fishing poles must be put down.
- Tell the students to fill in their data tables for "Year 1 End" with the number of each species of fish that remains in their ocean. Record the value of their catch in the "Year 1 Income" column. Any fish remaining on the table, still attached to the fishing pole, or destroyed during fishing do not count. Once their tables are filled out, the students can eat the goldfish they caught.
- Adjust the number of fish in each ocean to account for reproduction by adding one new fish of each species for each two that remain. Keep in mind that there must be a food source for each species to allow for survival. If no food source remains, remove that species from the ocean.
- Repeat steps 6-8 three more times until there have been four years of fishing.
- Instruct the students to use their data to create a line graph showing the changes in their fish population over time.
- Have each group report to the class the final number of fish remaining in their oceans after year four. Some oceans may be completely empty of fish. Others may have established a way to fish sustainably so that there are more fish than when they started. Discuss the various strategies the different groups used (or didn't use) to manage their oceans.
- As a class, discuss the following questions:
- What is overfishing?
- Why does overfishing happen?
- What are the effects of overfishing?
- What is stewardship and why is it important?
- How can the world continue to fish in a sustainable manner?
Activity 3: Public Service Announcement
- Give each student 1 copy of the Public Awareness Campaign Rubric. Divide students into groups to complete. Tell students they will be creating a Public Service Announcement (PSA) Poster encouraging the community to eat fish sustainably. PSAs are messages in the public interest. They can be found on television, radio, print or other media. PSAs are different from commercial advertising. Rather than marketing a product or service, PSAs are messages that benefit the public by raising awareness of an issue and influencing attitudes or actions for the good of mankind.
- Optional adaptation: Rather than completing an entire poster, this activity can be adapted for individual student work by assigning students to make a flyer or educational brochure.
- In preparation for creating the PSA, have students research aquaculture using some of the following resources:
- Book: World Without Fish by Mark Kurlansky
- Website: Monterey Bay Seafood Watch
- TED Talks: “The four fish we’re overeating- and what to eat instead” and “The case for farm fishing”
- Possible poster prompts teachers may use to guide students are:
- Why is seafood a healthy protein source?
- Why is overfishing a problem?
- Why is farm raised fish a healthy option?
- What is sustainable fishing?
- Why is aquaculture considered a future food source?
- After projects are complete, have students present posters with the class or share via gallery walk.
Concept Elaboration and Evaluation
After conducting these activities review and summarize the following key concepts:
- Fish and seafood provide a healthy source of protein and vitamins. USDA dietary recommendations encourage eating fish and seafood twice per week.
- Fishing open waters for the harvest of fish and other seafood requires close monitoring to prevent damage to the ocean ecosystem and to ensure the animal populations remain healthy and sustainable for the future.
- There are both benefits and drawbacks to converting natural ecosystems (oceans and other natural waters) into agricultural ecosystems (fish farms).
Have students create a digital PSA from the poster via prezi or video by using editing tools like Movie Maker, iMovie, Explain Everything, Vimeo, or Spark Video. Assign roles such as producer, actor/narrator, set designer/graphics designer, etc.
Review as a class or assign students to read the article, Aquaculture Programs Help Students Dive in to Careers from the North Carolina Field and Family database.
Have students visit a fish research facility and/or interview local fishers, fish biologists or other people involved with local fisheries.
Have students research oysters and how oyster farming can produce a positive impact on water quality.
Introduce students to an Arctic Char Fish Farm and discover the unique attributes of this fish both on the farm and as a culinary dish.
Discuss how culture and geography impact dietary choices. Have students research countries who consume high quantities of fish and seafood. Discuss geography and see if students can identify a correlation between cultural diets and proximity to source. Do locations closest to the sea typically consume more seafood? Students can also learn more about catfish and its cultural roots in the Southern United States.
Explore careers in the aquaculture industry. Learn what a Fish Biologist does to research and educate the public about fish issues.
Assign students to research common fish and seafood dishes in the United States and discover if it is typically farm-raised, wild-caught, or both.
- Activity 1 was added by the National Center for Agricultural Literacy.
- Activity 2 was adapted with permission from Blue World TVs lesson, The Lifespan of Overfishing.
Suggested Companion Resources
North Carolina Farm Bureau Ag in the Classroom
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