Example #1

Suppose that a researcher captured and individually marked 75 fish on day 1. Two days later, a total of 100 fish were captured of which 25 were marked.

  1. How many columns are in the capture history matrix?
  2. How many rows are in the capture history matrix?
  3. What does a row for an individual fish in the capture history look like for …
    1. A fish captured in both samples?
    2. A fish captured in the first but not the second sample?
    3. A fish captured in the second but not the first sample?
    4. A fish captured in neither sample?

Example #2

A researcher sampled a stream weekly for 8 weeks.

  1. How many columns are in the capture history matrix?
  2. How many rows are in the capture history matrix?
  3. What does a row for an individual fish in the capture history look like for …
    1. A fish marked in week 2 and recaptured in weeks 7 & 8?
    2. marked in week 3 and then not seen again?
    3. marked in the first week, captured again in week 3, and captured again in week 5, but not again?

Example #3

Use the following summary of capture histories to answer the questions further below.

Capture History    001 010 011 100 101 110 111
Frequency of fish   17  20   4  19   5   8   2
  1. How many capture events were used?
  2. How many total fish were captured?
  3. How many fish were captured in the first sample and then not seen again?
  4. How many fish were captured in the first sample and seen again?
  5. How many fish were captured in the first sample?
  6. How many fish were captured in the third sample?
  7. How many fish in the second sample were recaptures (i.e., previously marked)?
  8. How many fish in the third sample were recaptures?
  9. How many fish were captured exactly twice?
  10. How many fish were never captured?