The management of the world’s fisheries is a controversial current issue that involves individuals from many different viewpoints – fishermen and women, environmentalists, park rangers, politicians, and shoppers at the seafood counter. The issue is that many of the world’s fisheries are overfished and have collapsed or are on the verge of collapse. This is but one example of the tragedy of the commons – where a limited common resource is overused because each individual person thinks, “If I don’t use this resource first, then somebody else will.” Students in this activity act as fishermen and women who need to share an ocean of fish and take in a catch. Groups soon realize that if they don’t set fishing limits and monitor the fish population, soon there are no fish left in the ocean.
Can define population.
Can graph changes in a population over time.
Can see how available resources determine the number and type of organisms that an environment can support.
Can see how humans impact natural resources.
Can identify common natural resources that humans impact.
Can devise strategies to manage natural resources.
Tragedy of the commons
Teams of 4 students
The tragedy of the commons was initially proposed as a hypothetical model to illustrate a much larger societal problem. In colonial times, there was often a common pasture (the commons) where all citizens of the town could take their livestock for grazing. Each individual farmer and his animals is motivated to use this pasture land to get the maximum benefit possible. However, as more animals use the resource, the pasture gets trampled and overgrazed until there is no grass left for anyone. Thus, if each farmer is motivated simply to maximize personal benefit, thus using the pasture as much as possible, the resource is soon no good to anyone.
Similarly, the ocean’s supply of fish is a common resource that is rapidly being depleted. The basic issue is that since 1950, the fishing industry has quadrupled its catch. According to the United Nations, 15 out of the 17 world fisheries are overfished or depleted. 90% of the large fish species in the oceans have been fished out in the last 50 years. In short, fish are being taken from the oceans faster than they can reproduce and grow. Many fisheries have already collapsed, sending hundreds of fishermen and women out of work. Without clear international controls and regulation, soon there will be no more fish in the seas. Many articles have been published in recent years describing the problem. For example, see the Economist, May 2005, Science Magazine, December 2003, and the San Francisco Chronicle, October 2004.
This activity is a way to help students recognize the problem by catching candy, peanut and cracker fish from paper plate oceans. Students will spend 4 years fishing in their oceans. Each “year” the students have 30 seconds to fish for as many fish as they can catch using straws and masking tape as their poles and hooks. Each fish has a different monetary value and each student much catch a minimum dollar amount of fish in order to stay in business the following year. Then the remaining fish in the ocean have a chance to reproduce. There must be at least 2 fish of that species to reproduce. In addition, the fish in their oceans have a food web and must have their food source still available in order to survive.
At the end of the game, some oceans will likely have overfished their fishery until there are no fish left. Others will have developed a strategy in order to maintain a sustainable fishing industry. The discussion at the end will look at the problem of overfishing and solutions that lead towards sustainable resource management. The stage is then set for solid discussions of resource management strategies for other shared environmental resources.
Students need a solid understanding of food webs (see Food Webs activity) and experience with monitoring population changes over time through tables and graphs (See Hare and Lynx Population Change activity).
- 4 fisherpersons will be fishing in each ocean (a paper plate). You cannot touch, tip or move the ocean!
- Each fisherperson will be given 2 fishing poles (straws) and a net (a short length of tape) to fish with. There should be NO fishing with hands! Each fisherperson will also get a boat (a napkin) onto which any fish that are caught should be placed. Fish that fall out of the boat onto the table do not count!
- You will be fishing in your ocean for 4 years. Each year you will have 30 seconds to bring in your catch.
- There are 4 different kinds of fish in the ocean. Each is worth a certain amount of money on the market. Goldfish are worth $3, Peanut Fish are worth $5, M&M Fish are worth $5, and Peanut M&M Fish are worth $10.
- You must earn at least $5 of income each year to stay in business. However, you should try 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 exist in a food web and need to have food in order to survive. Goldfish eat seaweed of which there is always a lot in the ocean. Peanut Fish and M&M Fish eat Goldfish; there must be at least 1 Goldfish in the ocean for these fish to survive. Peanut M&M Fish eats both Peanut Fish and M&M fish; there must be at least 1 Peanut Fish and 1 M&M fish in the ocean for these fish to survive.
The idea for this lesson came from Jen McGonigle, a science teacher from Haddonfield, New Jersey, who shared this activity during the Exploratorium’s Summer Teacher Institute.
Wikipedia has a wonderful summary of the tragedy of the commons. It includes an excellent review of Hardin’s original essay on the topic, historical background about where the concept of the commons originated, and many examples of modern commons problems: littering, air quality, water quality, population growth, logging, etc.
Ecology (Life Sciences)
5. Organisms in ecosystems exchange energy and nutrients among themselves and with the environment. As a basis for understanding this concept:
a. Students know energy entering ecosystems as sunlight is transferred by producers into chemical energy through photosynthesis and then from organism to organism through food webs.
b. Students know matter is transferred over time from one organism to others in the food web and between organisms and the physical environment.
e. Students know the number and types of organisms an ecosystem can support depends on the resources available and on abiotic factors, such as quantities of light and water, a range of temperatures, and soil composition.
6. Sources of energy and materials differ in amounts, distribution, usefulness, and the time required for their formation. As a basis for understanding this concept:
b. Students know different natural energy and material resources, including air, soil, rocks, minerals, petroleum, fresh water, wildlife, and forests, and know how to classify them as renewable or nonrenewable.
Investigation and Experimentation
7. c. Construct appropriate graphs from data and develop qualitative statements about the relationships between variables.