Reference

Calculate indices
calc_ppr_index()	Calculate the PPR index
calc_ppr_scaled()	Scale PPR index by total primary production
calc_mtl_index()	Calculate the mean Trophic Level
calc_fogarty_index()	Calculate the Fogarty index
calc_ryther_index()	Calculate the Ryther index
Plot indices
plot_ppr_index()	Plot the Primary Production Required index (scaled)
plot_fogarty_index()	Plot the Fogarty index
plot_ryther_index()	Plot the Ryther index
plot_mtl_index()	Plot the mean trophic level index
explore_species_composition()	Explores species composition based on landings
Intermediate functions Functions used that aid in the creation of the indices.
get_trophic_level()	Obtain trophic level data from rfishbase
select_top_x_percent()	Select species in top x of landings
select_troph()	Combine trophic level data
capitalize_first_letter()	Capitalize first letter of string