Size Structure

- Read Chapter 6 in
*Introductory Fisheries Analyses with R*and these notes and consider the items below.- Why is an analysis of size structure important in fisheries management?
- What does a “length frequency” show?
- What R function is used to convert measured lengths to length categories or bins? What arguments does this function require?
- What R function is used to make a length frequency table from a length category variable? What arguments does this function require?
- What R function is used to make a length frequency histogram? What arguments does this function require?
- What kind of “function” is used to visually compare length frequencies between two groups?
- What is a proportional size distribution (PSD) indice?
- What are the five Gabelhouse length categories?
- What R function can be used to find the values for the Gabelhouse length categories for a particular species of fish? What arguments does this function require?
- Explain what an “incremental” PSD indice is?
- Explain what a “traditional” PSD indice is?
- What R function can be used to easily compute PSD indices and associated confidence intervals? What arguments does this function require?
- What statistical test is used to compare the distribution of lengths between groups of fish? What R function is used to perform this test?
- What statistical test is used to compare the frequency of individuals in Gabelhouse length categories between groups of fish? What R function is used to perform this test?

- Read Anderson’s “Catch & Release or Selective Harvest” and consider the items below.
- What is a PSD? How is it calculated?
- What characteristics might describe a population (of, say, Bluegill) that has a PSD of less than 10?
- What is a PSD for a Bluegill population that “in balance.”
- What is selective harvest? Why might a fish manager develop a regulation to promote selective harvest?