Here a Fish,  There a Fish - Tom Cod

Research Question: How and why do Tom Cod populations change along the Poquonnock River?

Part A: Read the background information

Atlantic Tom Cod (Microgadus tomcod) are anadromous fish that travel short distances between fresh and salty water.  They are a type of codfish native to coastal waters on the eastern coast of North America. They typically live year-round in estuaries with younger fish inhabiting fresh or slightly brackish waters. They can be found in  the mouths of streams or rivers, salt marshes, and eelgrass beds.  Eventually, they move into deeper, nearshore waters. Tomcod are also known as ‘frost fish’ for spawning in the cold winter waters of December-January, often under the ice. They spawn upriver over gravelly or sandy bottoms.  Fry are planktivores, going on to prey upon small crustaceans, fish, worms, and mollusks.  They have also been noted as feeding on the eggs, larvae and juveniles of their own species. Tomcod are an important food for many predatory birds and larger fish--including the striped bass and bluefish.

Part B: Prediction and Reasoning

Study the background information provided on Tom Cod (above), and take the virtual tour of the Poquonnock River, paying close attention to habitat descriptions.  Write answers to the following prompts on your sheet of paper.

  1. Make a prediction:  In July, where along the Poquonnock River would you expect to see the most tom cod?

  2. Explain your reasoning:  WHY do you think tom cod are most likely to be in this location?

Part C: Analyze the Data

Look at the dataset below.  On your piece of paper, illustrate the data by making a graph.  Your graph should have clear labels on both the x-axis and the y-axis.  The type of graph (scatterplot, column graph, etc) is up to you.

This table shows the number of tom cod captured while seining at each location, on a single day in July 2019.  

 Part D: Interpret the Results and Make Arguments from Evidence

On your sheet of paper, answer the following questions:

  1. Make a claim that answers the research question (one sentence).

  2. What evidence was used to write your claim? Reference specific parts of your graph.

  3. Explain your reasoning. Make sure to connect your answer to what you have learned about the biology of tom cod.

  4. Was your prediction supported by the results? Use evidence to explain why or why not.

  5. How would you follow up? Describe a new question that should be investigated to build on these results, and what future data should be collected to answer your question.

Congratulations!  Your final analysis should include the following components:

  • A statement of the research question that you chose/were assigned

  • Your prediction and your reasoning

  • Your labelled graph

  • Your answers to the results questions

Share your results with your teacher, and/or by emailing it to Project O:, attn: Dr. Molly

**Educators and/or homeschool parents: educator guides are available for all research projects. 

Email to request an educator guide**

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