For many anglers that live on the water or that have friends with water access, having a bait holding pen at the dock is a luxury.
With a nicely constructed bait pen at the dock, you can fish in advance for bait, and then store them at the dock for several days. There are many factors that come into play with the length of time certain baits can take in your pen.
For example, hardy baits such as blue runners can live in your pen for weeks as long as you feed them. If you don