This repository contains the data and scripts developed by the Population Evaluation Team (PET) subgroup 1 to assess the effect of potential management measures on the future population trajectory of North Atlantic right whales. The PET PVA consists of a core stage-structured model and several submodels (mortality, reproduction, entanglement, vessel strike, prey availability, and prey accessibility). The primary scripts are as follows:
PVA_functions.RPVA_scenarios.RPVA_projections.R
The first script uses object-oriented programming to define functions and attributes consistent with the life-history of NARWs. The second script is used to design scenarios related to wounding rates and prey dynamics. The third script sets up the parameters of the population projection and simulates an nBoot number of replicated population trajectories that incorporate stochasticity and uncertainty.
The inputs folder contains various objects representing both data and posterior distributions from other models that were used to provide estimates of demographic parameters. These include:
NARW_food_covariates_1986-2019.Rdata= indices of prey availabilityNARW_posteriors_MORT.csv= parameters related to injury/mortalityNARW_posteriors_REPRO.csv= parameters related to reproductionPVA_population_t0.Rdata= starting population size in 2019
Conditional on the coded structure of the population and the specified collection of parameters defining demographic attributes, simulated populations are projected through time (e.g., 100 years) to examine distributions of future population sizes and probabilities of extinction (or quasi-extinction). These outputs can be used to examine anticipated outcomes of management measures that are aimed at reducing threats to the population.
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