The ability to separate or sequester individual fish identified as req
uiring further inspection would represent a milestone in the developme
nt of inspection and control systems for fish in sea nets. This paper
reports work on a technique which enables a visually identified fish t
o be selectively drawn away from the other fish and towards the camera
. The development of a device capable of sequestering the fish thus lo
calised is the subject of future development. The technique for attrac
ting the fish relies on the development of a conditioned response in t
he whole population which associates a light stimulus with food delive
ry. This is found to be a relatively easy and rapid process. The targe
t fish is then selectively exposed to this stimulus and so is attracte
d to the light source while the others remain undisturbed. Tank trials
suggest that a target fish can be selectively attracted to the camera
with a reliability approaching 70%. Further work is needed to establi
sh whether this concept can be used in sea nets at commercial stocking
densities. (C) 1997 Elsevier Science B.V.