Features


Growth and length-weight relationship

Compute the von Bertalanffy growth function, growth performance indices and compare different growth curves. Fit the length-weight relationship by model I and model II linear regression and nonlinear least squares.

Reproduction and recruitment

Calculate age and length at first maturity by probit regression. Compute spawning potential ratios (SPR). Determine recruitment variability from catch-curve regressions and fit stock-recruitment relationships.

Mortality

Compute total mortality rates by catch-curve, Jones and Van Zalinge plot and Hoenig equation. Estimate natural mortality rates by several indirect methods.

Virtual population methods

Perform virtual population analysis (VPA) by solving classic catch equation (Gulland) on catch-at-age data or cohort analysis on catch-at-length data (Jones). Compute predictive Thompson and Bell model and find the factor that maximizes yields.

Beverton and Holt yield-per-recruit model

Compute biomass and yield-per-recruit from Beverton and Holt model by numerical integration or Gulland approximation using weight based von Bertalanffy growth function. Relative yields are also available. Find Fmax and F0.1 and make isopleth diagrams.

Selectivity

Compute "effective mesh size" from VPA or cohort analysis. Estimate selection ogive from catch-curve.

Monte Carlo methods

R has built in random number generation for Beta, Binomial, Cauchy, Chi-squared, Exponential, F, Gamma, Geometric, Hypergeometric, Log-normal, Logistic, Negative-binomial, Normal, Poisson, Student-t, Uniform, Weibull and Wilcoxon distributions. FishAssess functions do not yet work in a direct Monte Carlo manner, but with some knowledge of R language doing it in a straightforward way is possible (i.e., one line combination of functions).

Continuously under construction...