He describes the usual application of a fishbone diagram for digging in to solve a problem. In addition to Ishikawa's Ms for manufacturing fishbones that Christian mentions, I've also used Ps or Ss. You don't have to stick with these. Try to think of all the factors present in your organizational system that can affect your current project, and come up with your own fishbone alphabet. :)
During a retrospective, the traditional fishbone works as a team activity for Generating Insights to help the group reflect on the data the they've gathered and dig into the root causes of issues.
However, Mr. Loyer offers a new way of applying this technique. He calls it the reverse fishbone and uses it to help a group anticipate what's to come and make plans for helping their project succeed. As a project manager, he notes that using this technique collaboratively helped him to perceive the project in a different way and understand needs he might otherwise have overlooked.
Consider using this reverse fishbone activity in your next retrospective to Decide What to Do by envisioning actions that could move the team closer to their goals.
A Flexible Framework for Agile Retrospectives:
Set the Stage Gather Data Generate Insights Decide What to Do Close the Retrospective
For more retrospective activities, check out the "retrospectives" category on this site.