TropFishR (version 1.6.2)

M_empirical: Empirical formulas for the estimation of natural mortality

Description

Functions to calculate the instantaneous natural mortality rate (M) according to 12 different empirical formulas.

Usage

M_empirical(
  Linf = NULL,
  Winf = NULL,
  K_l = NULL,
  K_w = NULL,
  temp = NULL,
  tmax = NULL,
  tm50 = NULL,
  GSI = NULL,
  Wdry = NULL,
  Wwet = NULL,
  Bl = NULL,
  schooling = FALSE,
  method
)

Arguments

Linf

infinite total length (TL) from a von Bertalanffy growth curve in cm.

Winf

infinite weight form a von Bertalanffy growth curve in wet weight-grams.

K_l

is the growth coefficient (per year) from a von Bertalanffy growth curve for length.

K_w

is the growth coefficient (per year) from a von Bertalanffy growth curve for weight.

temp

average annual temperature at the surface in degrees centigrade.

tmax

the oldest age observed for the species.

tm50

age when 50% of the population is mature [year] ("age of massive maturation").

GSI

gonadosomatic index (wet ovary weight over wet body weight).

Wdry

total dry weight in grams.

Wwet

total wet weight at mean length in grams.

Bl

vector with body lengths in cm for size dependent mortality estimates (method = "Gislason")

schooling

logical; if TRUE it is accounted for the schooling behaviour of the species, only for Pauly's methods. Default is FALSE.

method

vector of method names. Any combination of following methods can be employed: "AlversonCarney", "Gislason" (size dependent mortality estimates), "GundersonDygert", "Hoenig", "Lorenzen", "Pauly_Linf", "Pauly_Winf", "PetersonWroblewski", "RikhterEfanov", "Roff", "Then_growth", or "Then_tmax". Please refer to Details to see which input parameters are required by each method.

Value

A matrix of M estimates.

Details

Function adapted from the mortality function of the fishmethods package by Gary A. Nelson (https://cran.r-project.org/web/packages/fishmethods/index.html).

Depending on the method different input parameters are required:

• "AlversonCarney" requires K_l and tmax,

• "Gislason" requires Linf, K_l and Bl,

• "GundersonDygert" requires GSI,

• "Hoenig" requires tmax,

• "Lorenzen" requires Wwet,

• "Pauly_Linf" requires Linf, K_l and temp,

• "Pauly_Winf" requires Winf, K_w and temp,

• "PetersonWroblewski" requires Wdry,

• "RikhterEfanov" requires tm50,

• "Roff" requires K_l and tm50,

• "Then_tmax" requires tmax,

• "Then_growth" requires Linf and K_l.

If accounting for schooling behaviour M is multiplied by 0.8 according to Pauly (1983).

References

Alverson, D. L. and M. J. Carney. 1975. A graphic review of the growth and decay of population cohorts. J. Cons. Int. Explor. Mer 36: 133-143.

Gislason, H., N. Daan, J. C. Rice, and J. G. Pope. 2010. Size, growth, temperature and the natural mortality of marine fish. Fish and Fisheries 11: 149-158.

Gunderson, D. R. and P. H. Dygert. 1988. Reproductive effort as a predictor of natural mortality rate. J. Cons. Int. Explor. Mer 44: 200-209.

Hoenig, J. M. 1983. Empirical use of longevity data to estimate mortality rates. Fish. Bull. 82: 898-903.

Lorenzen, K. 1996. The relationship between body weight and natural mortality in juvenile and adult fish: a comparison of natural ecosystems and aquaculture. J. Fish. Biol. 49: 627-647.

Pauly, D. 1980. On the interrelationships between natural mortality, growth parameters, and mean environmental temperature in 175 fish stocks. J. Cons. Int. Explor. Mer: 175-192.

Pauly, D., 1983. Some simple methods for the assessment of tropical fish stocks. FAO Fish.Tech.Pap., (234): 52p. Issued also in French and Spanish

Peterson, I. and J. S. Wroblewski. 1984. Mortality rate of fishes in the pelagic ecosystem. Can. J. Fish. Aquat. Sci. 41: 1117-1120.

Rikhter, V.A., and V.N. Efanov, 1976. On one of the approaches to estimation of natural mortality of fish populations. ICNAF Res.Doc., 76/VI/8: 12p.

Roff, D. A. 1984. The evolution of life history parameters in teleosts. Can. J. Fish. Aquat. Sci. 41: 989-1000.

Sparre, P., Venema, S.C., 1998. Introduction to tropical fish stock assessment. Part 1. Manual. FAO Fisheries Technical Paper, (306.1, Rev. 2). 407 p.

Then, A. Y., J. M. Hoenig, N. G. Hall, D. A. Hewitt. 2015. Evaluating the predictive performance of empirical estimators of natural mortality rate using information on over 200 fish species. ICES J. Mar. Sci. 72: 82-92.

Examples

# NOT RUN {
M_empirical(Linf = 80, K_l = 0.5, temp = 25, tmax = 30,
     method = c("Pauly_Linf","Hoenig"))

# }