4.1 - Introduction

Life cycle computations in CRiSP Harvest are performed on an annual basis. The sequence of computations reverses the procedures employed in the cohort analysis used to generate the stock-specific input data. The annual computational sequence is illustrated in Fig. 4.1 and outlined below:

• Population ageing
• Natural ocean mortality
• Preterminal (ocean) fishing mortality
  • Legal harvest
  • Incidental mortality (shakers and CNRs)
• Maturation
• Terminal fishing mortality
  • Legal harvest
  • Incidental mortality (shakers and CNRs)
• Adult escapement (ages 3, 4, and 5)
• Pre-spawning mortality (inter-dam losses) for some stocks
• Spawning escapement
• Production of progeny in the next year.

The remaining five sections of this chapter describe the functional relationships of the model. Natural survival processes are described first, followed by production processes, fishing processes, catch ceiling management, and in-river management.

Although many of the parameters are year specific, year indices have been deleted to make the equations easier to interpret. Brief descriptions of all variables follow each equation. More detailed notation and variable definitions are described in Chapter 7 (not available at this time).

Fig. 4.1 Illustration of the annual computation cycle in CRiSP Harvest.