To cite package 'a4a' in publications use:

  Colin Millar and Ernesto Jardim (). a4a: A flexible and robust stock
  assessment framework. R package version 1.8.3.9001.

A BibTeX entry for LaTeX users is

  @Manual{,
    title = {a4a: A flexible and robust stock assessment framework},
    author = {Colin Millar and Ernesto Jardim},
    note = {R package version 1.8.3.9001},
  }

  Millar, C.P., Jardim, E., Osio G.C., Mosqueira, I. 201x. a4a: A
  flexible and robust stock assessment framework. Submitted to PLOSone.

A BibTeX entry for LaTeX users is

  @Article{,
    title = {a4a: A flexible and robust stock assessment framework},
    journal = {Subbmitted to PLOSone},
    volume = {xx},
    number = {x},
    pages = {xx-xx},
    year = {201x},
    author = {Colin P. Millar and Ernesto Jardim and G. Chato Osio and Iago Mosqueira},
  }