M_Lorenzen: Compute age-varying natural mortality (M) based on Charnov et...

In nikolaifish/bamExtras: Functions and Data in Support of Stock Assessments with the Beaufort Assessment Model (BAM)

Compute age-varying natural mortality (M) based on Charnov et al (2013) and scale based on constant M

Description

Compute age-varying natural mortality (M) based on Charnov et al (2013) and scale based on constant M

Usage

M_Lorenzen(
  a,
  Linf,
  K,
  t0,
  par_wl_a = 1,
  par_wl_b = 3,
  aP = 0,
  M_constant = NULL,
  aMin = 0,
  par_a = 3.69,
  par_b = -0.305
)

Arguments

a	ages at which to compute M
Linf	length infinity
K	growth coefficient
t0	age (time) at length zero
par_wl_a	a parameter from weight~length conversion equation weight = par_wl_a*length^par_wl_b
par_wl_b	b parameter from weight~length conversion equation weight = par_wl_a*length^par_wl_b
aP	proportion of age (value between 0 and 1) at which to compute length (e.g. aP=0.5 to compute length at midyear)
M_constant	constant M value used to scale age-varying M. Defaults to NULL. M will be scaled if a numeric value of M_constant is supplied.
aMin	minimum age to include in computation of scaling factor when scaling M
par_a	a parameter for Lorenzen equation par_a*W^par_b. Defaults to value from Lorenzen et al. (1996; Table 1, ocean system) par_a=3.69.
par_b	b parameter for Lorenzen equation par_a*W^par_b. Defaults to value from Lorenzen et al. (1996; Table 1, ocean system) par_b=-0.305.

Note

Input parameters for von Bertalanffy growth equation and weight~length equation should have units that result in weight in grams (g), which is what the Lorenzen equation is based on.

Author(s)

Nikolai Klibansky

References

Lorenzen, K. 1996. The relationship between body weight and natural mortality in juvenile and adult fish: a comparison of natural ecosystems and aquaculture. Journal of Fish Biology 49:627-642.

Examples

## Not run: 
# M for Black Sea Bass
M_Lorenzen(a=0:11,Linf = 502, K = 0.173, t0 = -0.97, M_constant=0.38, aMin=2, par_wl_a=5.02e-05, par_wl_b=2.77)

## End(Not run)

nikolaifish/bamExtras documentation built on July 21, 2023, 8:26 a.m.