Total Mortality

- Read Sections 11.1 and 11.2 (
*skip Section 11.2.2*) in*Introductory Fisheries Analyses with R*and these notes and consider the items below.- Define A, C
_{t}, C_{t+1}, and Z. - What is the formula for computing annual mortality from catches that are separated by a single year?
- Describe the difference between longitudinal and cross-sectional catch-at-age data.
- What must be true for a vector of consecutive catches-at-age to be equal when extracted from longitudinal and cross-sectional data.
- What is the equation for the “catch-curve” model (that shows how catch is related to time)? Show how this equation can be linearized.
- How is Z estimated from catch-curve data?
- How is A estimated from Z?
- What is the characteristic shape of catch curve data? Specifically, identify three regions on the curve.
- Why does the catch curve have the shape described in the previous question?
- What are the assumptions of a catch curve model for estimating Z?
- What R function can be used to efficiently perform a catch curve estimate of Z?
- What R function is used to extract the estimates of Z and A from this function?
- What R function is used to extract confidence intervals for Z and A from this function?

- Define A, C
- Read Miranda and Bettolli (2006) Sections 6.1-6.3 (the complete reading) and consider the items below.
- What is “mortality”?
- What is the characteristic shape of catch curve data? Specifically, identify three regions on the curve.
- Why does the catch curve have the shape described in the previous question?
- What are the assumptions of a catch curve model for estimating Z?
- What assumption about recruitment is made for a catch curve? Is this a realistic assumption? How do modest violations of this assumption affect the estimates of Z?
- How large of a sample is needed for a catch curve analysis?
- What is a weighted catch-curve analysis?