What should be done if in a fishing vessel and needing attention, aside from using radio communication?

Setting off a distress flare is an effective way to signal for attention when you're on a fishing vessel and require assistance. Distress flares are specifically designed for emergencies and are highly visible, making them a trusted method for alerting nearby vessels or aircraft to your situation. The bright flame and distinctive color of a flare can be seen from a significant distance, even in poor visibility conditions, which increases the likelihood of gaining assistance quickly.

Using a signal mirror can be a useful method for signaling in certain situations, particularly in daylight, but it may not be as effective in low visibility or if there are no vessels nearby to see the reflection. Similarly, raising a signal flag is a traditional method for signaling, but it may not be immediately recognized by others unless they are trained to look for such signals, and it may not be effective in all weather conditions. Turning on all navigation lights can help with visibility at night, but it typically serves more for indicating your own vessel's presence rather than signaling for help.

In emergency situations where immediate assistance is needed, the use of a distress flare stands out as the most effective and recognized alternative to radio communication.