Production of cyprinids for re-stocking purposes - Part 1. Controlled reproduction (Artificial spawning)
European Network for the Dissemination of Aquaculture
RTD Information (Q5CA-2000-30105) and previously FAIR-3837, Aquaflow ref. :
TL2003-200
Production
of stocking material of wild cyprinids is one of the most important hatchery
activities in Poland, especially from an economical point of view.
Several species, reproduced and reared under controlled conditions
and/or in ponds, are used for angling or for restoration when the sort is
endangered.
In
this project, induced reproduction was studied in asp (Aspius aspius), dace (Leuciscus
leuciscus), ide: wide and yellow forms (Leuciscus
idus), chub (Leuciscus cephalus)
and vimba bream (Vimba vimba). All
these species do not reproduce spontaneously in captivity, so hormonal
treatment is needed to obtain gametes. Spawners were collected from natural
waters (except golden ide), in most cases during autumn. They were kept over
winter in earthen ponds or in commercial hatcheries. In spring, the selected
species were transported to a laboratory hatchery, where fish from both
sexes were kept in 1000-L tanks with controlled light and thermal
conditions. Before spawning, asp and dace broodstock were kept at 10°C, ide
at 12°C, and chub and vimba bream at 16-17°C. Oocytes maturity is
recognized using the 4-stage scale, as below:
Stage
1 - germinal vesicle in central position,
Stage
2 - early migration of germinal vesicle (less than half of radius),
Stage
3 - late migration of germinal vesicle (more than half of radius),
Stage
4 - periphery germinal vesicle or germinal vesicle breakdown (GVBD).
Samples
of oocytes were taken using a catheter. Three different spawning agents were
tested: human chorionic gonadotropin (hCG) at maximum total dose of
2000IU.kg -1, carp pituitary extract (CPE) at maximum total dose
of 4mg.kg-1 and GnRH analogue (18–40µg.kg-1) with
dopamine antagonist: metoclopramide (8–20mg.kg-1). After
injection, the water temperature was raised in each case by 2°C.
In all cases (except dace), the application of
hormonal treatment led to higher production of milt. Fish treated with CPE
and GnRHa produced a significantly higher volume of milt with higher
spermatozoa motility in comparison to control groups. Males, under hCG
treatment, produced semen with a higher sperm motility. The females from
control group did not ovulate; neither did fish treated with hCG. Other
hormonal treatments usually gave rise to 100% ovulation. A lower level of
ovulation was noted in chub and, more notably, in vimba bream. The latency
time, time between hormonal injection and ovulation, differed between
species and groups, but in all cases, the differences were especially noted
between groups treated with CPE and GnRHa. The shortest latency time was
observerdin the CPE group. Embryo survival to the eyed-egg-stage was usually
high (over 80%).
After spawning, fish were kept for two additional
weeks for observation of their mortality. The mortality of spawners was
found to be highly species-specific. The highest level of survival was noted
in ide (mortality usually 0%), the lowest in chub (mortality up to 50%) and
vimba bream (mortality up to 72%).
For more information, contact:
KUCHARCZYK Dariusz
University of Wamia and Mazury in Olsztyn - Department of Lake and River
Fisheries
Oczapowskiego 5
PL-10-719 Olsztyn-Kortowo
Poland
Phone : +48 89 523 4436
Fax : +48 89 523 3969
e-mail: darekk@moskit.uwm.edu.pl