2.3.4. Maturation

Age and size at maturation vary strongly between individuals due to phenotypic plasticity. This plasticity in maturation is modeled by a deterministic linear maturation reaction norm (LMRN) that represents all the age-length combinations at which an individual can become mature [Stearns, 1992, Stearns and Koella, 1986]. In this framework, individuals become sexually mature when their growth trajectory in term of body length intersects the LMRN, so that the maturity status of individuals of school at time step is then described as:

\[\begin{split}m(i,t) = \begin{cases} 0 & \text{if $L(i,t) < m_0(i) + m_1(i) a(i,t)$ (immature)} \\ 1 & \text{if $L(i,t) \geq m_0(i) + m_1(i) a(i,t)$ (mature)} \end{cases}\end{split}\]

with \(m_0(i)\) and \(m_1(i)\) the intercept and slope of the LMRN, respectively.