Effects of photoperiod and
light intensity on growth and activity of juvenile haddock (Melanogrammus
aeglefinus)
E.A.
Trippel, S.R.E. Neil-2002
Aquaculture, 217(1-4): 633-645
Abstract:
Enhancement of growth of juvenile haddock (Melanogrammus
aeglefinus) was achieved through photomanipulation. After 24 weeks
(August–January), hatchery-reared haddock under 24 h light were 53–60%
heavier than those under natural photoperiod. In a second 24-week
experiment, haddock were grown under five photoperiod regimes (natural
photoperiod, 12, 16, 20 and 24 h light) with two light intensities (30 and
100 lx) at 24 h. Continuous light (and 20 h light) resulted in the greatest
growth response, though other seasonally unchanging photoperiods (12 and 16
h light) also resulted in faster growth than natural photoperiod. Reduced
light intensity, from 100 to 30 lx, at 24 h, led to a further 11%
improvement in body mass. The effects of photomanipulation declined as
temperatures decreased in late autumn and winter. Locomotor activity was the
greatest under natural photoperiod (100 lx), less at 24 h (100 lx) and
lowest at 24 h (30 lx). Lower swimming activity under continuous dim light
may translate into metabolic savings and increased body mass. Integrating
these findings with research on larval haddock suggests a period in the
ontogeny exists during which bright light should be dimmed to maximize
growth and this perhaps coincides with changes in body morphology and
behaviour associated with benthic foraging.
(Fisheries and Oceans Canada, St. Andrews Biological
Station, 531 Brandy Cove Road, St. Andrews, New Brunswick, Canada E5B 2L9,
e-mail: trippele@mar.dfo-mpo.gc.ca
)