Gonad Differentiation and
Gamete Management: Influence of Storage Duration of Ovulated Eggs Prior to
Fertilisation on the Early Ontogenesis of Sterlet (Acipenser ruthenus)
and Siberian Sturgeon (Acipenser baeri)
E.
Gisbert, P. Williot-2002
International Review of Hydrobiology, 87(5-6):
605-612
Abstract:
The influence of short-term storage (0, 2, 4, 6, 9
and 12 h) in coelomic fluid at 15 °C of ovulated eggs of mature females
from sterlet (Acipenser ruthenus) and Siberian sturgeon (Acipenser
baeri) was studied. The percentage of fertilization, embryonic survival,
abnormally developing embryos, hatching and larvae with malformations at
hatching was measured. The results showed that ovulated eggs from A.
ruthenus retained their fertilizability during 2-4 hours after ovulation
depending on the maternal origin (83.5-43.7%; P < 0.05). The
fertilization rate of batches of Siberian sturgeon eggs ranged from 55.7 to
21.9% at ovulation time. Between 4 and 6 hours after ovulation, the
percentage of fertilized eggs and surviving embryos of A. baeri
significantly decreased (P < 0.05). Ovulated eggs inseminated after 12
hours of storage in coelomic fluid at 15 °C showed a considerable reduction
of their fertilizability that ranged from 61-35% in A. ruthenus and
from 44-25% in A. baeri. Reductions in the embryonic survival rates
were also observed: the decrease ranged from 58 to 38% in sterlet, and from
45 to 11% in Siberian sturgeon, recpectively. Hatching rates were also
affected by the insemination time, egg batches presenting the highest values
were those inseminated between 0-2 and 0-4 hours after ovulation in A.
ruthenus (28.6-64.9%) and A. baeri (16.7-26.3%), respectively. At
hatching, the lowest rates of malformed larvae with 5.6-11.4% in both
species were mainly observed amongst those larvae obtained from egg batches
inseminated between 0-4 and 0-6 hours after ovulation, respectively. No
significant differences were found between larvae obtained from egg batches
of A. ruthenus and A. baeri inseminated at different times (P
> 0.05). The results showed that ovulated eggs of A. ruthenus and A.
baeri stored in coelomic fluid at 15 °C lost their fertilizability and
viability, and became over-ripe between 2-4 and 6 hours after ovulation,
respectively.
(Cemagref,
UR Ressources Aquatiques Continentales, 50 Avenue de Verdun, Cestas cedex,
33612, France, e-mail: patrick.williot@cemagref.fr)