What data are needed
and who will provide them?
¥Nt+1 = Nt+B-D+I-E
¥
¥For PseudocalanusÉ
¥N = population  Bucklin, Durbin
¥B = birth rates  Runge
¥D = mortality  Runge, Ohman
¥I = immigration  Pringle, McGillicuddy
¥E = emigration  Pringle, McGillicuddy