Sets h so that the species reaches maturity size w_mat at the maturity
age age_mat if it feeds at feeding level f0.
Details
If age_mat is missing in the species parameter data frame, then it is
calculated from the von Bertalanffy growth curve parameters k_vb and
(optionally t0) taken from the species parameter data frame. This is not
reliable and a warning is issued.
If no growth information is given at all for a species, the default is set
to h = 30.
See also
Other functions calculating defaults:
get_f0_default(),
get_gamma_default(),
get_ks_default()