Bur (1984) examined the population dynamics of Freshwater Drum (*Aplodinotus grunniens*) in Lake Erie in the late 1970s. In one part of his study, he measured the total length (TL) of all 1577 drum sampled and extracted scales for age estimation from a proportionate sample from each 10 mm length interval. The length and age data are recorded in **FWDrumLE2.csv** (view, download, meta).

- Separate the observed data into age- and length-samples. How many fish are in each sample?
- Add a variable to the age-sample that contains the 10 mm TL categories. Construct a table of the
**number**(not proportion) of fish in each age and 10 mm TL category in the age-sample. From these results, compute each of the following*by hand*(i.e., not using R).- How many Freshwater Drum in the age-sample are in the 230 mm TL category?
- How many age-5 Freshwater Drum are in the age-sample?
- What proportion of Freshwater Drum in the 300 mm TL category are age 5?
- What proportion of Freshwater Drum in the 200 mm TL category are age 4?

- Construct an
**observed**age-length key from the table above (using R). From these results answer the following questions.- What proportion of Freshwater Drum in the 210 mm TL category should be assigned age 5?
- How many of thirty Rock Bass in the 250 mm TL category should be assigned age 4?
- Construct a plot of the
**observed**age-length key. Are there any potential anomalies in the plot that would suggest that a smoothed age-length key could be appropriate?

- Construct a
**smoothed**age-length key. From these results answer the following questions.- What proportion of Freshwater Drum in the 210 mm TL category should be assigned age 5?
- How many of thirty Rock Bass in the 250 mm TL category should be assigned age 4?

Continue with these data here.

from Derek H. Ogle , created 08-Nov-15, updated 08-Nov-15, Comments/Suggestions.