Induced sexual maturation of
the European eel Anguilla anguilla and fertilisation of the eggs
B.
Hedegaard Pedersen-2003
Aquaculture, 224(1-4): 323-338
Abstract:
The aim of the present study was to induce sexual
maturation in females of the European eel Anguilla anguilla using a
protocol similar to that successful for Anguilla japonica. Inducing
maturation in the female European eel has proven difficult in the extreme,
as only one research group has so far reported fertilisation with subsequent
embryonic and larval development in A. anguilla. The present study
performed two experiments. In experiment A, the 10 surviving females
received a weekly injection with salmon pituitary extract (SPE) at a dose of
18.2 mg pituitary powder per week and fish, and in experiment B, females
were injected twice weekly and received a dose of 36.4 mg pituitary per fish
and week. Only two experiment B fish had viable eggs. In both experiments,
final oocyte maturation and ovulation was induced by injection of 17,20
β-dihydroxy-4-pregnen-3-one (DHP) at about 2 µg/g body weight.
Maturation time was 16–25 weeks in experiment A and 7.5–11.5 weeks in
experiment B. In the final stages of oocyte maturation, female A.
anguilla showed highly individual rates of oocyte development, and as
injection protocol depended on oocyte development, six protocols had to be
used. The only protocol which resulted in fertilisation of eggs with
subsequent development of larval bodies––and in one case hatching,
although delayed, of larvae––was weekly SPE injection followed ca. 40 h
later by an extra SPE injection (18.2 mg pituitary powder), 10 h after which
DHP was injected.