Processes Growth

Growth

Individuals of a given school are assumed to grow in both size and weight at a given time only when the amount of food they ingests fulfills their maintenance requirements, i.e., only when their predation efficiency at that time is greater than the predation efficiency to ensure body maintenance of the school.

$$ G(s, a) = M_{\Delta}(s, a) \times \frac{S_R(s, a) - C_{S_R}(s)} {1 - C_{S_R}(s)}\ if\ S_R(s, a) \ge C_{S_R} $$

$$ G(s, a) = 0\ if\ S_R(s, a) < C_{S_R} $$

where $C_{S_R}$ is the critical predation efficiency and $S_R$ the predation success rate of the school.

$M_{\Delta}(s, a) = \lambda \times \Delta L(a)$ is the maximum growth rate at age $a$ for species $s$.

$\Delta L(a) = L(a + 1) - L(a)$ is the mean length increase determined from a growth function (Von Bertalanffy or Gompertz growth function), while $\lambda$ is a factor that allows to control the maximum length at a given age.

Parameter	Description
growth.java.classname.sp#	Class name of the age to length conversion
predation.efficiency.critical.sp#	Critical predation success ($C_{S_R}$)
species.delta.lmax.factor.sp#	$\lambda$ (default = 2)

The two growth functions are described in the following links:

• Von Bertalanffy growth
• Gompertz