120-years of ecological monitoring data shows that the risk of overhunting is increased by environmental degradation for an isolated marine mammal population: the Baltic grey seal.

Code for the manuscript "120 years of ecological monitoring data indicates that current Baltic grey seal hunting quotas are unsustainable. " .zip file containes code and data compiled to assess the impact of hunting on the Baltic grey seal.

Scripts:

Basic_model.R Age structured single sex popualiotn model

Generation_time_calculator.R Function to calcualte generation time Parameters.R Parameters for the blatic grey seal population model

1_Ordered_scripts.R Grey seal PVA script 1, load packages and base scripts for core parameters and functions

2_Historical_data.R Grey seal PVA script 2, plot hitstorical populaiton estimates alongside current aerial survey data 3_Explicit_populaiton_modelling.R Grey seal PVA script 3, estimate intrinsic growth rate givne moult survey data 4_Fertility_survival_estimation.R Grey seal PVA script 4, estimate fertility based on data and parameterise a leslie matrix through modification of first year survival

5_Undisturbed_population_modelling.R Grey seal PVA script 5, estimate vital rates fro an undistturbed popualiton by adding hunted animals back into the popualiton

6_Scenarios.R Grey seal PVA script 6, Running simulations with a range of scenarios outlined in Table 1

7_Risk_averages.R Grey seal PVA script 7, Estimating the risk of i) stabilising below the precautionary RL, stabilising below the critical RL, 10% decline in three gneerations, 50% decline in 3 gneerations, 70% decline in 3 generations

*scripts should be run in order

Data:

Areial_Counts.csv moult survey counts for the whole baltic

Historical.csv estimates of historical popualoitn size for the whole baltic from hunting records

Ice.csv record of maximum extend of baltic sea ice

age_structures.csv age, source country, and manner of death for seals

bycatch_structure.csv age structure of bycaught animals

grey_seal_hunting.csv summary of hunting in Sweden and Finland

hunt_structure.csv age structure of hunted animals 

population_counts.csv moult survey counts for the whole baltic

reproduction.csv summary of reporductive rates accross age classes

Compiled risks.csv outputs of risk modelling from popualiotn simulations