360
J. R. 5. BLAXTER AND F. 0. T. HOLLIDAY
These observations were all made at sea, mainly in an attempt to
develop light fisheries. Loukashkin and Grant (1959) made a detailed
aquarium study of the effect of coloured and white light on Sardinops
caerulea; this species preferred blue and green light and disliked red
light, exhibiting a fright reaction both to this and flashing white light.
2. Varaability of the reaction
While attraction to artificial lights has been frequently observed,
especially in young clupeids, such reactions will vary widely depending
on the environment and the physiological state and age of the fish, BB
well as on the type of stimulus itself. Lovetskaya (1956) found 8etwoml.
differences in the Caspian sprat (2 Clupeonella) and Shubnikov (1960)
found that more ripe Clupeonella males were attracted than females.
This could have been associated with the higher feeding activity of the
males. Belyaeva and Nikonorov (1960) found that the behaviour to
light& changed in relation to the condition of the fish, ecological factors,
amount of moonlight, temperature, turbidity, current and the nature
of the light source. Schuler and Krefft (1951) found that herring (1)
would not pass through a thermocline of 4.63 deg. C in 6 m under the
attraction of a lamp.
The intensity of the light source was found to be important by
Borisov (1 955) ; higher intensities attracted Clupeonella more effectively.
Of different colours used, yellow was most effective, but probably
because it was the brightest light. Nikonorov and Patejev (1959)
gave details of the best light condition for Clupeonella. Blaxter and
Parrish (1958) found, too, that higher light intensities collected more
organisms, presumably due to their greater penetration.
3. Explanation for light attraction
This has been roviewed by Belyaova and Nikonorov (1960), who
suggested that ( ( curiosity ”, feeding, positive phototaxis, hypnosis,
following of optimum light intensity, disorientation or conditioned
reflex might be responsible. They favoured the idea of a ( ( testing
reflex ”, referring particularly to Clupeonella. Zusser (1958b) and
Borisov and Protasov (1960) considered that phototaxis was no
explanation, but that attraction waa due to a conditioned response ; the
fish normally associated feeding with light, to the extent that attraction
to light had become a conditioned response associated with feeding, the
unconditioned response. This requires to be proved experimentally.
Verheijen (1958) developed the idea that attraction was due to a masa
disorientation, such as that caused by lighthouses to migrating birds
and insects. The mechanism of this disorientation would be aa follows :
J. R. 5. BLAXTER AND F. 0. T. HOLLIDAY
These observations were all made at sea, mainly in an attempt to
develop light fisheries. Loukashkin and Grant (1959) made a detailed
aquarium study of the effect of coloured and white light on Sardinops
caerulea; this species preferred blue and green light and disliked red
light, exhibiting a fright reaction both to this and flashing white light.
2. Varaability of the reaction
While attraction to artificial lights has been frequently observed,
especially in young clupeids, such reactions will vary widely depending
on the environment and the physiological state and age of the fish, BB
well as on the type of stimulus itself. Lovetskaya (1956) found 8etwoml.
differences in the Caspian sprat (2 Clupeonella) and Shubnikov (1960)
found that more ripe Clupeonella males were attracted than females.
This could have been associated with the higher feeding activity of the
males. Belyaeva and Nikonorov (1960) found that the behaviour to
light& changed in relation to the condition of the fish, ecological factors,
amount of moonlight, temperature, turbidity, current and the nature
of the light source. Schuler and Krefft (1951) found that herring (1)
would not pass through a thermocline of 4.63 deg. C in 6 m under the
attraction of a lamp.
The intensity of the light source was found to be important by
Borisov (1 955) ; higher intensities attracted Clupeonella more effectively.
Of different colours used, yellow was most effective, but probably
because it was the brightest light. Nikonorov and Patejev (1959)
gave details of the best light condition for Clupeonella. Blaxter and
Parrish (1958) found, too, that higher light intensities collected more
organisms, presumably due to their greater penetration.
3. Explanation for light attraction
This has been roviewed by Belyaova and Nikonorov (1960), who
suggested that ( ( curiosity ”, feeding, positive phototaxis, hypnosis,
following of optimum light intensity, disorientation or conditioned
reflex might be responsible. They favoured the idea of a ( ( testing
reflex ”, referring particularly to Clupeonella. Zusser (1958b) and
Borisov and Protasov (1960) considered that phototaxis was no
explanation, but that attraction waa due to a conditioned response ; the
fish normally associated feeding with light, to the extent that attraction
to light had become a conditioned response associated with feeding, the
unconditioned response. This requires to be proved experimentally.
Verheijen (1958) developed the idea that attraction was due to a masa
disorientation, such as that caused by lighthouses to migrating birds
and insects. The mechanism of this disorientation would be aa follows :