Weight-Length Relationships

- Read Sections 7.1-7.4 in
*Introductory Fisheries Analyses with R*and these notes and consider the items below.- What are five things that weight-length relationships are used for?
- Which are more precise – length or weight measurements? Explain.
- What is the difference between a common and natural logarithm?
- Why is linear regression inappropriate to model weight-length data?
- Weight-length data follows what kind of function for most fish species?
- Demonstrate how this function is transformed to a linear function?
- What parameter does the slope of the transformed model represent?
- What R function is used to fit a linear regression?
- What R function is used to extract the regression parameter estimates?
- What R function is used to extract the regression parameter confidence intervals?
- What R function is used to determine if there is a significant relationship between weight and length (or their transformed values)?
- How does one check whether the assumptions of a linear regression have been met or not?
- What does it mean about fish shape over time if the slope parameter is equal to 3? If it is not equal to 3?

- Read Pope and Kruse (2007) Sections 10.1 (
*the complete chapter is here*) and consider the items below.- What are the two things the weight-length relationships have historically been used for?
- Weight-length data follows what kind of function for most fish species?
- Demonstrate how this function is transformed to a linear function?
- What type of values does the b parameter usually take?
- What value of b is indicative of allometric growth?
- Define allometric growth?
- What kinds of “things” can impart a bias in the weight-length relationship?
- How does one check whether the assumptions of a linear regression have been met or not?