ELEFAN_SA function

ELEFAN_SA

Electronic LEngth Frequency ANalysis with simulated annealing for estimating growth parameters.

ELEFAN_SA(
  lfq,
  seasonalised = FALSE,
  init_par = list(Linf = 50, K = 0.5, t_anchor = 0.5, C = 0, ts = 0),
  low_par = NULL,
  up_par = NULL,
  SA_time = 60 * 1,
  maxit = NULL,
  nb.stop.improvement = NULL,
  SA_temp = 1e+05,
  verbose = TRUE,
  MA = 5,
  addl.sqrt = FALSE,
  agemax = NULL,
  flagging.out = TRUE,
  plot = FALSE,
  plot.score = TRUE
)

Arguments

• lfq: a list consisting of following parameters:

  • midLengths midpoints of the length classes,
  • dates dates of sampling times (class Date),
  • catch matrix with catches/counts per length class (row) and sampling date (column);

• seasonalised: logical; indicating if the seasonalised von Bertalanffy growth function should be applied (default: FALSE).

• init_par: a list providing the Initial values for the components to be optimized. When set to NULL the following default values are used:

  • Linf length infinity in cm (default is the maximum length class in the data),
  • K curving coefficient (default: 0.5),
  • t_anchor time point anchoring growth curves in year-length coordinate system, corrsponds to peak spawning month (range: 0 to 1, default: 0.5),
  • C amplitude of growth oscillation (range: 0 to 1, default: 0),
  • ts summer point (ts = WP - 0.5) (range: 0 to 1, default: 0);

• low_par: a list providing the lower bounds for components. When set to NULL the following default values are used:

  • Linf length infinity in cm (default is calculated from maximum length class in the data),
  • K curving coefficient (default: 0.01),
  • t_anchor time point anchoring growth curves in year-length coordinate system, corrsponds to peak spawning month (range: 0 to 1, default: 0),
  • C amplitude of growth oscillation (range: 0 to 1, default: 0),
  • ts summer point (ts = WP - 0.5) (range: 0 to 1, default: 0);

• up_par: a list providing the upper bounds for components. When set to NULL the following default values are used:

  • Linf length infinity in cm (default is calculated from maximum length class in the data),
  • K curving coefficient (default: 0.01),
  • t_anchor time point anchoring growth curves in year-length coordinate system, corrsponds to peak spawning month (range: 0 to 1, default: 0),
  • C amplitude of growth oscillation (range: 0 to 1, default: 0),
  • ts summer point (ts = WP - 0.5) (range: 0 to 1, default: 0);

• SA_time: numeric; Maximum running time in seconds (default : 60 * 1).

• maxit: Integer. Maximum number of iterations of the algorithm. Default is NULL.

• nb.stop.improvement: Integer. The program will stop when there is no any improvement in 'nb.stop.improvement' steps. Default is NULL

• SA_temp: numeric; Initial value for temperature (default : 1e5).

• verbose: logical; TRUE means that messages from the algorithm are shown (default : TRUE).

• MA: number indicating over how many length classes the moving average should be performed (defalut: 5, for more information see lfqRestructure ).

• addl.sqrt: Passed to lfqRestructure . Applied an additional square-root transformation of positive values according to Brey et al. (1988). (default: FALSE, for more information see lfqRestructure ).

• agemax: maximum age of species; default NULL, then estimated from Linf

• flagging.out: logical; passed to lfqFitCurves . Default is TRUE

• plot: logical; Plot restructured counts with fitted lines using plot.lfq and lfqFitCurves (default : FALSE).

• plot.score: logical; Plot simulated annealing score progression. (Default: plot.score=TRUE)

Returns

A list with the input parameters and following list objects:

• rcounts : restructured frequencies,

• peaks_mat : matrix with positive peaks with distinct values,

• ASP : available sum of peaks, sum of posititve peaks which could be potential be hit by growth curves,

• ncohort : maximum age of species,

• agemax : maximum age of species,

• par : a list with the parameters of the von Bertalanffy growth function:

  • Linf : length infinity in cm,
  • K : curving coefficient;
  • t_anchor : time point anchoring growth curves in year-length coordinate system, corrsponds to peak spawning month,
  • C : amplitude of growth oscillation (if seasonalised = TRUE),
  • ts : summer point of oscillation (ts = WP - 0.5) (if seasonalised = TRUE),
  • phiL : growth performance index defined as phiL = log10(K) + 2 * log10(Linf);

• Rn_max : highest score value (absolute value of cost function, comparable with ELEFAN and ELEFAN_GA).

Details

A more detailed description of the simulated annealing (SA) can be found in Xiang et al. (2013). The score value cost_value is not comparable with the score value of the other ELEFAN functions (ELEFAN or ELEFAN_GA).

Examples

## synthetic lfq data example
data(synLFQ4)
plot(synLFQ4, Fname="catch")

 (takes approximately 2 minutes)
output <- ELEFAN_SA(synLFQ4, SA_time = 60*2, seasonalised = TRUE, MA = 11,
  init_par = list(Linf = 75, K = 0.5, t_anchor = 0.5, C = 0.5, ts = 0.5),
  low_par = list(Linf = 70, K = 0.3, t_anchor = 0, C = 0, ts = 0),
  up_par = list(Linf = 90, K = 0.7, t_anchor = 1, C = 1, ts = 1))
output$par
output$Rn_max

# view fit
plot(output)

# or
plot(output, draw = FALSE)
lfqFitCurves(output, col=1, par=output$par, draw=TRUE)$ESP

# compare to original parameters
tmp <- lfqFitCurves(output, col=4, lty=1,
   par=list(Linf=80, K=0.5, t_anchor=0.25, C=0.75, ts=0.5), draw=TRUE)
tmp$fESP
output$Rn_max

References

Brey, T., Soriano, M., and Pauly, D. 1988. Electronic length frequency analysis: a revised and expanded user's guide to ELEFAN 0, 1 and 2.

Pauly, D. and N. David, 1981. ELEFAN I, a BASIC program for the objective extraction of growth parameters from length-frequency data. Meeresforschung, 28(4):205-211

Xiang, Y., Gubian, S., Suomela, B., & Hoeng, J. (2013). Generalized simulated annealing for global optimization: the GenSA Package. R Journal, 5(1), 13-28.