Lesson Notes:

I envision prefacing this lab with an intro to north atlantic cod fishing. Find some photos of cod, maybe some pics of fishing boats coming back to the harbor loaded with fish. Definitely a map showing where in the North Atlantic this is taking place (off of Newfoundland). You could tell students that cod was coveted for it’s white flaky meat as well as the oil made from their livers. Thousands of people emigrated from Europe to take part in the fishing because it was such a booming business in the 1950’s and 60’s.

I will probably remind students that ecosystems are interconnected and the point of this activity is to find out how various organisms were/are effected by the overfishing of cod. They should keep this interconnectedness in mind as they go through the activity.

Northern Shrimp: Up until 1990 my largest predator was the cod fish but thanks to the fisherman I now don’t have to worry about them. Without many predators for a couple of years my species was able to reproduce very successfully so there are currently a lot of shrimp in the North Atlantic. Our food source- zooplankton- has been depleted because of the boom in shrimp population and if our numbers continue to increase we may run out of food.

Cod: As an apex predator with nutrient-rich waters in the North Atlantic our population was thriving. We didn’t have many predators in the deep cold water and there was plenty of shrimp and small fish such as herring to feed on. However, in 1950 fisherman began capturing us by the ton. It is estimated that our population is only 1% of what it was in 1977. With our population nearly wiped out, our prey- such as herring- have had population explosions and are now the top predators. This affects the survival rates of cod eggs and fry (baby fish) so our population may never recover.

Fishermen: In 1950’s thousands of fishermen moved to the Atlantic coast of Canada to make money in the booming cod industry. Advances in technology, such as larger boats better nets, allowed fishermen to take more and more fish every year until a peak of 800,000 tons harvested in 1968. It was known that the fishing practices were unsustainable but greed and a lack of government regulation meant that more and more cod was being caught. The cod population declined every year after 1968 and in 1992 a moratorium was placed on cod fishing. 40,000 people lost their jobs over night and the economy of eastern Canada was devastated.

Grey Seal: We used to compete against the cod in the Northern Atlantic for food as we both fed largely on small fish, shrimp, and lobsters. Since the cod have been wiped out we no longer have to compete for food and there is more food around since cod aren’t eating the shrimp and herring. With plenty of food for us, our population is booming. But with more seals in the water there are also more sharks, as they feed on seals, so we have to keep a constant lookout.

Herring: Atlantic cod used to be our largest predator. Now that the cod have been wiped out, however, our population has steadily increased. We eat pretty much anything in the ocean that is less than 20mm in size so that includes worms, snails, small fish, and fish eggs. While cod used to be our predators, their eggs and small fry (baby fish) are actually our prey. It is unlikely that the cod population will recover very quickly because we eat every cod egg we can find. Now that the cod have been wiped out our largest predators are humans. Fishermen now target us because our populations are booming and they can no longer fish for cod.

Zooplankton: We are a group of small animals that drift freely in the waters of the northern atlantic. Many of us are microscopic but others, such as jellyfish, can be seen with the naked eye. Zooplankton are all heterotrophic (need to eat other organisms) and our most common food source is phytoplankton. Our most common predators in the north atlantic are shrimp, lobsters, and tiny fish. Since the 1970’s the population of shrimp has increased greatly, which means that more and more of us zooplankton are being eaten.

Phytoplankton: We are a group of free-floating photosynthetic microorganisms. In other words, we are tiny organisms that make our own food by converting sunlight into sugar. Phytoplankton produce roughly 40% of the world’s oxygen and remove CO2 from the water. We do not eat anything but we do have predators such as zooplankton and shrimp.

Name______Block______Date______

2.2: Atlantic Cod Tea Party

Directions: In the space provided, record at least 2 important points or facts that you hear from each of the different people at the tea party. Be sure to meeteveryoneso that you are familiar with how each species has been affected by the crash of the cod population in the North Atlantic.

Table 1: Various Organisms and Their Impacts in the North Atlantic Ocean

Organism / Role in Food Web & Impact from Cod Overfishing
Cod
/
  • I eat:
  • I am eaten by:
  • How am I effected by cod overfishing:

Grey Seal
/
  • I eat:
  • I am eaten by:
  • How am I effected by cod overfishing:

Fishermen
/
  • I eat:
  • I am eaten by:
  • How am I effected by cod overfishing:

Northern Shrimp
/
  • I eat:
  • I am eaten by:
  • How am I effected by cod overfishing:

Zooplankton
/
  • I eat:
  • I am eaten by:
  • How am I effected by cod overfishing:

Phytoplankton
/
  • I eat:
  • I am eaten by:
  • How am I effected by cod overfishing:

Herring
/
  • I eat:
  • I am eaten by:
  • How am I effected by cod overfishing:

Use the Graph, above, to answer the following questions.

  1. Describe the overall trend of fish being caught between the years 1860 and 1960.

______

  1. In what approximate year were the most cod caught? ______
  2. How many tons of fish were caught in that year? ______
  3. Give an explanation for the rapid decline in number of fish caught between 1968 and 1975.

______

In the space below, construct a food web that includes all of the organisms listed in Table 1. Be sure that the arrows are pointing in the correct direction (flow of energy) and include a brief sketch of each organism.

  1. Of the organisms listed in Table 1, list one producer, one primary consumer, and one secondary consumer.

Producer
Primary Consumer
Secondary Consumer
  1. Briefly describe one example of predation found in the north Atlantic ecosystem?

______

  1. Briefly describe one example of overexploitation found in the north Atlantic ecosystem?

______

  1. Given that the cod population has been decimated, fishermen are now turning to the shrimp industry. Briefly describe TWO ways that overexploitation of the shrimp population would impact the north Atlantic ecosystem.

#1 - ______

#2 - ______

  1. What is biodiversity AND how has biodiversity been effected in the North Atlantic?

______