Fishing vessels are generally classified by their __________.

Fishing vessels are primarily classified by the type of fishing apparatus used. This classification is essential because the type of gear and method employed in fishing directly affects the vessel's design, operations, and the regulations it must adhere to. For example, vessels that trawl have specific structural requirements to handle the heavy gear and catch, while those that are designed for longlining or gillnetting will have different features geared towards those specific practices.

The types of apparatus can include nets, traps, lines, or other specialized equipment, and this classification helps in identifying the vessel's primary function and operational capabilities. This classification is crucial for regulatory purposes, safety guidelines, and conservation efforts, as different fishing methods impact marine ecosystems in various ways.

Length, engine type, and color can be important attributes for various purposes, such as determining stability, horsepower, or visual identification respectively, but they do not define the fundamental operating category of the vessel in the way the type of fishing apparatus does.