Lumens

Lumens count the total light a source emits in all directions. It says nothing about how that light is distributed. A 1000 lumen flood and a 1000 lumen spot behave completely differently.

For fishing, the headline number is the least useful spec on the box. What you actually use is a dim setting for tying knots without destroying your night vision, and occasionally a bright burst to find something. A headlamp with a good 20 lumen low mode beats one with a 1500 lumen maximum and no fine control.

Maximum output also drains a battery fast and most lamps step down from it within minutes, so the advertised number is rarely sustained. Manufacturers measure at the moment of switch-on, which is the most flattering possible reading.

For context, 20 to 50 lumens is plenty for tying a knot at arm's length, 200 lights a path, and anything above 500 is for finding something at distance. A night on the bank rarely needs more than the low setting.