1. Observe the effects of over harvest on a hypothetical offshore fishery when the primary motive is profit.
2. Identify methods to create a sustainable fishery operation.
Seafood is a valuable resource, with the industry worth approximately $70 billion per year in the United States. To meet the high demand for seafood we have increased the number and size of ships as well as advancing net design to maximize the harvest of seafood and more recently to reduce the catch of non-target species such as turtle and dolphins. This pattern of resource exploitation is not sustainable as we are harvesting many species faster than they can reproduce. The northeastern United States’ fishing industry was built on the abundant cod fishery. The population of cod off of the northeastern coast is now so small that it is not economically feasible to fish for them because there are not enough left to be able to catch enough to pay for operating expenses.
1. Computer with Microsoft excel 2000 or better (older versions might work)
2. Fish harvest worksheet, “offshore fish harvest.xls” (save it to your computer or a disk)
1. In this exercise your objective is to maximize profits and develop your fishing fleet as funds become available. There are two sizes of ship (small and large) and you can find purchase price and operating expenses in rows 1-3 of the worksheet. Rows 7-10 reflect your operating expenses for the first season with 1 small boat.
2. Look at Season 1. Along the left side is an account summary reflecting your account balance (what you are worth), your operating costs, your balance to sea (what is left after paying operating costs), Balance after catch (balance to sea + value of catch), and balance after purchase (purchase of additional ships). Cell 17F indicates the value of your season’s catch and rows 21-23 are where you indicate the purchase of new ships. THE ONLY CELLS YOU CAN CHANGE ARE THE QUANTITY CELLS FOR PURCHASING SHIPS (in yellow). YOU MAY ONLY PURCHASE A MAXIMUM OF 2 OF EACH SIZE SHIP PER SEASON. The shipyards can only build them so fast.
3. After you indicate your purchase of ships at the end of season 1, scroll down to season 2 and make sure your balance to sea is positive. IF THE BALANCE TO SEA IS NEGATIVE (printed in red) YOU NEED TO CHANGE THE NUMBER OF SHIPS YOU PURCHASED IN THE PREVIOUS ROUND. You will not be able to purchase any ships during season 1 because you won’t have the money.
4. In season 2 you can see your fleet composition (rows 30-32) and your account summary (rows 30-38). Purchase as many ships as you can afford (up to the limit of 2 of each type per season). Your balance to sea for the next season must be in the black (not red).
5. Continue through the rest of the seasons, purchasing ships as you can afford them. If you begin running out of money you can sell back ships by typing a negative number in the purchase cell (-1 will sell back one ship).
After completing all 16 seasons view the accounting worksheet by clicking the “accounting” tab at the bottom of the excel window. Print the Accounting Worksheet and all three graphs.
1. In what season did your fleet value reach its peak?
2. In what season did your number of fish caught reach its peak?
3. How do those two numbers compare? What explanation can you give for this result?
4. In what season did you have to start selling back ships?
5. View the Harvest Progress graph. What season should have been the last season that you bought any ships?
6. View the Fish Population Size graph. Due to the exponential growth of wild populations, the fish population was able to rebound to the carrying capacity after each of the early seasons. Which was the first season that the starting population size did not fully rebound?
7. How does that compare to the peak in fish harvest value? (Harvest Progress Graph)
8. Did the population sizes begin to increase in the final seasons? If so, why?
9. View the Fish Harvest graph. If the large ships can catch 7500 fish per season and the small ships can catch 3500 fish per season, why did the number of fish caught decrease before you began selling back ships?
1. How could this fishery be harvested sustainably?
2. Could more money be made by fishing sustainably than by trying to maximize early profits?
Test your conclusions. Delete the ship purchase cells (yellow) in the worksheet and conduct the experiment again.