More effective induction of spawning with
long-acting GnRH agonist in the shi drum, Umbrina cirrosa L.
(Sciaenidae, Teleostei), a valuable candidate for Mediterranean mariculture
A. Barbaro, A. Francescon, D. Bertotto, G. Bozzato, I. Di Maria, P.
Patarnello, F. Furlan, L. Colombo-2002
Journal
of Applied Ichthyology, 18(3):
192-199
Abstract:
Three experiments of spawning induction in shi drum, Umbrina
cirrosa L., were performed in six different commercial Italian
hatcheries from May to August (water temperatures: 19-29 °C; salinity:
21-37 p.p.t.). In the first experiment, 119 females (1-4.7 kg), subdivided
into 29 lots, were injected with a single dose (2, 5, 8, 10, 15 and 20 µg
kg-1 body weight) of short-acting gonadotropin- releasing hormone
agonist (GnRHa-S), des-Gly10,[D-Ala6]-LH-RH ethylamide. In the other two
experiments, 85 females (0.7-5.8 kg), subdivided into 22 and four lots, were
treated with one (40 or 80 µg kg-1) or three doses (40 µg
kg-1) of long-acting GnRHa (GnRHa-L), respectively. GnRHa-S
stimulated spawning in 69% of the 29 treated lots; the number of eggs laid
reached a maximum of 130 000 and a weighted mean of 29 200 total eggs kg-1.
GnRHa-L elicited a spawning response in 95% of the 22 one-dose treated lots;
the number of laid eggs was higher than with GnRHa-S, reaching a maximum of
213 100 and a weighted mean of 59 400 total eggskg-1. The yield
of developing embryos in 67% of the single GnRHa-L treatments was higher
(sometimes up to three times) than with GnRHa-S. Triple treatments of the
four lots of females with GnRHa-L always resulted in spawning responses; the
best result corresponded to a number of total laid eggs of 358900 eggskg-1
with a yield of 177300 developing embryos.
(CNR,
Istituto Biologia Mare, Venice, Italy)