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In the ypr
package a population is considered to be
group of interbreeding fish that are indistinguishable to anglers.
Ecotypes are groups of individuals with a population that have different
life-history strategies. Consequently, ecotypes must share key fishery
(pi
, Llo
, Lup
, Nc
,
rho
, Hm
and q
) and stock
recruitment (BH
, RK
, tR
and
Rmax
) parameters.y To use a yield-per-recruit approach it
is also necessary to assume that the relative proportion of recruits
(RPR
) adopting each life-history strategy is independent of
the size and composition of the parental stock.
Consider a population with a smaller ecotype and a second larger ecotype that delays maturation in order to achieve sufficient size to switch to piscivory which allows it to grow much larger.
library(ypr)
library(ggplot2) # for plotting
<- ypr_ecotypes(
ecotypes Linf2 = 200,
L2 = c(100, 50),
Ls = c(50, 75),
pi = 0.05,
names = c("small", "large"),
RPR = c(0.8, 0.2))
ypr_plot_schedule(ecotypes) + scale_color_manual(values = c("black", "blue"))
ypr_plot_schedule(ecotypes, x = "Age", y = "Spawning") + scale_color_manual(values = c("black", "blue"))
ypr_plot_fish(ecotypes, color = "white") + scale_fill_manual(values = c("black", "blue"))
ypr_plot_fish(ecotypes, x = "Length", y = "Caught", color = "white", binwidth = 15) + scale_fill_manual(values = c("black", "blue"))
ypr_plot_sr(ecotypes, biomass = TRUE)
ypr_tabulate_sr(ecotypes, biomass = TRUE)
#> # A tibble: 3 × 7
#> Type pi u Eggs Recruits Spawners Fecundity
#> <chr> <dbl> <dbl> <dbl> <dbl> <dbl> <dbl>
#> 1 unfished 0 0 4085. 0.667 1.27 6431.
#> 2 actual 0.05 0.05 2483. 0.549 0.879 5653.
#> 3 optimal 0.0833 0.0833 1705. 0.455 0.656 5200.
ypr_tabulate_yield(ecotypes, biomass = TRUE)
#> # A tibble: 2 × 8
#> Type pi u Yield Age Length Weight Effort
#> <chr> <dbl> <dbl> <dbl> <dbl> <dbl> <dbl> <dbl>
#> 1 actual 0.05 0.05 0.253 7.97 73.6 5474. 0.487
#> 2 optimal 0.0833 0.0833 0.290 7.64 71.9 5026. 0.825
ypr_plot_yield(ecotypes, biomass = TRUE)
These binaries (installable software) and packages are in development.
They may not be fully stable and should be used with caution. We make no claims about them.
Health stats visible at Monitor.