Thanks to U.S. Coast Guard light-display standards for night navigation, you can identify any type of vessel and its activity, as well as determine where to safely enter and exit a harbor.
To make this work, however, you have to know the standards. It’s not a simple feat, as there are more than 48 different light configurations for vessels at night. But if you do a lot of night fishing, you should know most of them. To learn more about identifying vessels at night, here are two sites that have interactive flash cards to help skippers learn how to identify vessels by their lights at night:
U.S. Coast Guard Navigation Center — Flash Cards
Sea Scout Ship 468 “Triton” — Navigation for Skippers (.pdf)