haddock data frame has 15 rows and 4 columns.
Age, weight at spawning, partial recruitment, and fraction mature data for haddock (Melanogrammus aeglefinus) used by Gabriel et al. (1989)
to calculate spawning stock biomass-per-recruit.
This data frame contains the following columns:
vector of ages
vector of weights at spawning for each age
partial recruitment vector
vector of fraction of females mature at age
Gabriel, W. L., M. P. Sissenwine, and W. J. Overholtz. 1989. Analysis of spawning stock biomass per recruit: an example for Georges Bank haddock. North American Journal of Fisheries Management 9: 383-391.