Researchers for the North Temperate Lakes Long-Term Ecological Research program have collected fish from a number of lakes in Wisconsin since 1981. The total lengths and weights of Yellow Perch (Perca flavescens) captured from Trout Lake from 1981-2006 are recorded in YPerchTL.csv (view, download, meta). Use these data to answer the following questions. [Note that these data came from this website. See the site for more information about the sampling protocol that produced these data.]

1. Remove the lakeid and spname variables from the data.frame as these variables are constant for all records. Also remove the CRAYTR, FYKNED, FYKNEL, MINNOW, TRAMML, and all of VGN0XX variables as very few Yellow Perch were captured in these gears. Use this data.frame for the remaining questions.
2. Create a new data.frame of Yellow Perch captured in just fyke nets.
3. Create a new data.frame of Yellow Perch captured in fyke nets and beach seines.
4. Create a new data.frame of Yellow Perch captured in 1998.
5. Create a new data.frame of Yellow Perch captured after 1999.
6. Create a new data.frame of Yellow Perch captured in the 1990s.
7. Create a new data.frame of Yellow Perch captured with only fyke nets in 2005.
8. Create a new data.frame of Yellow Perch captured with only beach seines and fyke nets in 1997.
9. Use the data.frame of Yellow Perch capture in fyke nets and beach seines for the following questions.
1. Sort the data by capture year.
2. Sort the data by total length within capture year.
3. Change the name of the length and weight variables to len and wt, respectively.
4. Create a new variable that is the total length in inches.
5. Create two new variables that are the common logarithms of the lengths (in mm) and weights.
6. Add a variable that contains 10 mm wide length categories.
7. Add a variable that contains the appropriate five-cell Gabelhouse length categories.

Save the script from this exercise as these data will be used in this plotting, this size structure, this weight-length relationship, and this condition exercise.

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