ypr is an R package that
implements equilibrium-based yield per recruit methods. Yield per
recruit methods can used to estimate the optimal yield (Walters and
Martell 2004) of a fish population with one or more ecotypes. The yield
can be based on the number of fish caught (or harvested) or biomass for
all fish or just large (trophy) individuals.
The key life history parameters are
- The growth coefficient (
k) and mean maximum length (Linf) from the Von Bertalanffy growth curve - The length at which 50% mature (
Ls) - The length at which 50% vulnerable to harvest (
Lv) - The annual interval natural mortality rate (
n) - The lifetime number of spawners per spawner at low density (
Rk)
and in the case of ecotypes
- The relative proportion of recruits that belong to that ecotype
(
RPR)
The calculations do not account for stochasticity, predator-prey dynamics, angler responses or density-dependent growth.
To install the latest release from CRAN
install.packages("ypr")To install the developmental version from GitHub
# install.packages("remotes")
remotes::install_github("poissonconsulting/ypr")library(ypr)
population <- ypr_population(Rk = 5, Ls = 50, Rmax = 100, rho = 0.6)
ypr_plot_schedule(population, x = "Length", y = "Spawning")
ypr_tabulate_schedule(population)
#> # A tibble: 20 × 11
#> Age Length Weight Fecundity Spawning NaturalMortality Vulnerability
#> <int> <dbl> <dbl> <dbl> <dbl> <dbl> <dbl>
#> 1 1 13.9 27.0 27.0 3.13e-56 0.2 3.13e-56
#> 2 2 25.9 174. 174. 2.91e-29 0.2 2.91e-29
#> 3 3 36.2 476. 476. 1.04e-14 0.2 1.04e-14
#> 4 4 45.1 918. 918. 3.46e- 5 0.2 3.46e- 5
#> 5 5 52.8 1469. 1469. 9.95e- 1 0.2 9.95e- 1
#> 6 6 59.3 2090. 2090. 1.00e+ 0 0.2 1.00e+ 0
#> 7 7 65.0 2747. 2747. 1.00e+ 0 0.2 1.00e+ 0
#> 8 8 69.9 3412. 3412. 1.00e+ 0 0.2 1.00e+ 0
#> 9 9 74.1 4065. 4065. 1 e+ 0 0.2 1 e+ 0
#> 10 10 77.7 4689. 4689. 1 e+ 0 0.2 1 e+ 0
#> 11 11 80.8 5274. 5274. 1 e+ 0 0.2 1 e+ 0
#> 12 12 83.5 5816. 5816. 1 e+ 0 0.2 1 e+ 0
#> 13 13 85.8 6310. 6310. 1 e+ 0 0.2 1 e+ 0
#> 14 14 87.8 6758. 6758. 1 e+ 0 0.2 1 e+ 0
#> 15 15 89.5 7160. 7160. 1 e+ 0 0.2 1 e+ 0
#> 16 16 90.9 7518. 7518. 1 e+ 0 0.2 1 e+ 0
#> 17 17 92.2 7836. 7836. 1 e+ 0 0.2 1 e+ 0
#> 18 18 93.3 8116. 8116. 1 e+ 0 0.2 1 e+ 0
#> 19 19 94.2 8363. 8363. 1 e+ 0 0.2 1 e+ 0
#> 20 20 95.0 8580. 8580. 1 e+ 0 0.2 1 e+ 0
#> # ℹ 4 more variables: Retention <dbl>, FishingMortality <dbl>,
#> # Survivorship <dbl>, FishedSurvivorship <dbl>ypr_plot_fish(population, color = "white")
ypr_tabulate_fish(population)
#> # A tibble: 20 × 8
#> Age Survivors Spawners Caught Harvested Released HandlingMortalities
#> <dbl> <dbl> <dbl> <dbl> <dbl> <dbl> <dbl>
#> 1 1 70.1 2.19e-54 4.39e-55 1.76e-55 2.63e-55 0
#> 2 2 56.1 1.63e-27 3.26e-28 1.30e-28 1.96e-28 0
#> 3 3 44.9 4.68e-13 9.36e-14 3.74e-14 5.62e-14 0
#> 4 4 35.9 1.24e- 3 2.48e- 4 9.93e- 5 1.49e- 4 0
#> 5 5 28.7 2.86e+ 1 5.72e+ 0 2.29e+ 0 3.43e+ 0 0
#> 6 6 21.1 2.11e+ 1 4.23e+ 0 1.69e+ 0 2.54e+ 0 0
#> 7 7 15.6 1.56e+ 1 3.11e+ 0 1.24e+ 0 1.87e+ 0 0
#> 8 8 11.5 1.15e+ 1 2.29e+ 0 9.16e- 1 1.37e+ 0 0
#> 9 9 8.43 8.43e+ 0 1.69e+ 0 6.74e- 1 1.01e+ 0 0
#> 10 10 6.20 6.20e+ 0 1.24e+ 0 4.96e- 1 7.44e- 1 0
#> 11 11 4.57 4.57e+ 0 9.13e- 1 3.65e- 1 5.48e- 1 0
#> 12 12 3.36 3.36e+ 0 6.72e- 1 2.69e- 1 4.03e- 1 0
#> 13 13 2.47 2.47e+ 0 4.95e- 1 1.98e- 1 2.97e- 1 0
#> 14 14 1.82 1.82e+ 0 3.64e- 1 1.46e- 1 2.18e- 1 0
#> 15 15 1.34 1.34e+ 0 2.68e- 1 1.07e- 1 1.61e- 1 0
#> 16 16 0.986 9.86e- 1 1.97e- 1 7.89e- 2 1.18e- 1 0
#> 17 17 0.726 7.26e- 1 1.45e- 1 5.81e- 2 8.71e- 2 0
#> 18 18 0.534 5.34e- 1 1.07e- 1 4.27e- 2 6.41e- 2 0
#> 19 19 0.393 3.93e- 1 7.86e- 2 3.15e- 2 4.72e- 2 0
#> 20 20 0.289 2.89e- 1 5.79e- 2 2.31e- 2 3.47e- 2 0
#> # ℹ 1 more variable: Ecotype <chr>ypr_plot_sr(population)
ypr_tabulate_sr(population)
#> # A tibble: 3 × 7
#> Type pi u Eggs Recruits Spawners Fecundity
#> <chr> <dbl> <dbl> <dbl> <dbl> <dbl> <dbl>
#> 1 unfished 0 0 286350. 80 159. 3600.
#> 2 actual 0.2 0.08 167831. 70.1 108. 3112.
#> 3 optimal 0.458 0.183 84129. 54.0 63.7 2641.ypr_tabulate_yield(population)
#> # A tibble: 2 × 8
#> Type pi u Yield Age Length Weight Effort
#> <chr> <dbl> <dbl> <dbl> <dbl> <dbl> <dbl> <dbl>
#> 1 actual 0.2 0.08 8.63 7.67 65.8 3112. 2.12
#> 2 optimal 0.458 0.183 11.7 6.87 62.6 2641. 5.82
ypr_plot_yield(population)
For more information see the Get Started vignette.
To interactively explore the effects of altering individual parameters on the schedule, stock-recruitment and yield see the ypr shiny app.
Development of ypr was partially supported by the Habitat Conservation Trust Foundation and the Ministry of Forests, Lands and Natural Resource Operations.
The hex was designed by The Forest.
Please report any issues.
Pull requests are always welcome.
Please note that the ypr project is released with a Contributor Code of Conduct. By contributing to this project, you agree to abide by its terms
Walters, Carl J., and Steven J. D. Martell. 2004. Fisheries Ecology and Management. Princeton, N.J: Princeton University Press.