The population biology of Lake Superior Lake Trout (*Salvelinus namaycush*) prior to 1950 was examined in detail by Sakagawa and Pycha (1971). In Table 1 of their paper, they presented the number of Lake Trout by age (from scales) collected in 4.5-inch mesh gillnets that were set between the Keweenaw Peninsula and Munising, MI in 1948. The numbers of Lake Trout caught for ages 3 to 14 were 5, 18, 21, 10, 45, 109, 95, 63, 42, 25, 13, and 4. Use these data to answer the questions below.

- Is this an example of a cross-sectional or longitudinal catch curve?
- Plot log(catch) versus age. Which ages best represent the descending portion of the catch curve? Explain.
- Using the regression method, find the following (with 95% confidence intervals):
- Instantaneous total mortality rate.
- Annual total mortality rate.
- Annual survival rate.

- Using the Chapman-Robson method, find the following (with 95% confidence intervals):
- Instantaneous total mortality rate.
- Annual total mortality rate.
- Annual survival rate.

- Mathematically show how to convert the instantaneous mortality rate to an annual mortality rate.

from Derek H. Ogle , created 08-Mar-19, updated 26-Dec-21, Comments/Suggestions.