An aquaculture luminaire and lighting system, and a lighting method

A method of providing underwater lighting for aquaculture, comprising:

• providing a luminaire having a light source arrangement for generating a first light output portion and a second light output portion, wherein, when in an intended operational orientation relative to the vertical, the light of the first light output portion has a downward direction component and the light of the second light output portion has an upward direction component, wherein the light of the second light output portion is all directed with an angle to the vertical greater than a threshold angle;
• and
• configuring, by actuating selected light sources of an array of light sources of the light source arrangement with different light sources providing a light output in different directions relative to the vertical, and in dependence on a depth at which the luminaire is to be used,
• a division of light between the first and second light output portions.