Effects of egg disinfection
and incubation temperature on early life stages of spotted wolffish
T.K. Hansen, I.B. Falk-Petersen-2001
Aquaculture
International, 9(4):
333-344
Abstract:
Eggs of spotted wolffish (Anarhichas minor
Olafsen) were incubated at constant 4, 6 and 8°C,
and disinfected with glutaric dialdehyde (150 p.p.m. for 5 min) once or
twice a month during two thirds of the incubation period, to prevent growth
of microorganisms. Hatching of apparently normal larvae started earlier when
eggs were disinfected twice a month compared to once a month at all
incubation temperature regimes. The time to 50% hatch was 900 and 920
day-degrees (16 and 16.5 weeks) at 8°C, 835
and 880 day-degrees (20 and 21 weeks) at 6°C
and 725 and 800 day-degrees (26 and 28.5 weeks) at 4°C,
in the egg groups disinfected twice or once a month, respectively. The best
survival until hatching was noted when eggs were disinfected twice a month
and incubated at 6 and 8°C. Survival was
very low at 4°C. Prematurely hatched larvae
were registered in all egg groups disinfected twice a month and the highest
frequency was noted in the 8°C groups. The
larval weight at normal hatching in the 6 and 8°C
groups was negatively correlated with incubation temperature and intervals
of disinfection during the incubation period, but after 42 days feeding with
live feed (unenriched Artemia) the weights of the larvae were not
significantly different. The specific growth rates of the larvae from the
eggs incubated at 6°C and 8°C
were 3.0% and 3.2%, respectively. The mean survival of larvae was between
88% and 96% at 42 days post-hatching. Young wolffish originating from the 6°C
incubation groups showed lowest mortality.