Use of Carbopol resin for carp pituitary administration improves the fertilization percentage of northern pike (Esox lucius Linnaeus) eggs in commercial hatcheries

Abstract

The efficiency of northern pike (Esox lucius Linnaeus) fry production via hormonal treatment of wintered broodstock is, in general, relatively low due to low egg fertilization percentage. It has been experimentally demonstrated that administration of acetone-dried carp pituitary extract in a slow-release vehicle of aqueous dispersion of Carbopol 971 P resin (CP) resulted in a higher mean fertilization percentage, possibly because the gradual hormone action could optimally control ovarian follicle maturation and ovulation. This new method of hormonal induction of ovulation was tested in a large-scale hatchery production of northern pike fry. In the present study, data on fertilization percentage collected between 2002 and 2006 at two prominent hatcheries in Hungary were analyzed. Administration of acetone-dried carp pituitary in a 2.5% CP vehicle resulted in higher fertilization (76.4 ± 7.7%; mean ± SD) compared to the saline vehicle group (59.3 ± 10.8%). The vehicle used did not affect the ovulation ratio. According to these results from large-scale production, the new method could be suitable to have wide application for induced breeding of northern pike.

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“…15: 575-581(2015) 578 injection. This is consistent with results of other studies that have used carp pituitary or other hormone gonadotropin-containing preparations (Billard and Marcel, 1980;Brzuska and Malczewski, 1989;Szabó, 2001Szabó, , 2003Szabó, , 2008. Szabó et al (2014) found similar ovulation efficacy for silver carp pituitary compared to carp pituitary in northern pike.…”

“…One spontaneously ovulated female from group 3 had higher fertilization and hatching rates, however, these data were limited and not comparable to other groups. Generally, hatching and fertilization rates found in our study were higher than those reported by other authors (De Montalembert et al, 1978;Billard and Marcel, 1980;Horváth, 1983;Szabó, 2001;2003;2008).…”

“…A single 3 mg kg -1 injection of carp pituitary is the only confirmed method of inducing mass ovulation in mature females harvested from ponds or lakes (Billard and Marcel, 1980). Pike broodstock held year-round in a pond environment or captured too early during the spring do not mature in hatchery conditions (Szabó, 2008). A lack of necessary environmental stimulation, in combination with handling stress, inhibits final oocyte maturation (FOM) and subsequent ovulation .…”

“…However, to date, studies have shown that replacement of CP by GnRHa with or without dopamine inhibitors has not been effective for induction of ovulation in pike (Billard and Marcel, 1980;Pecha et al, 1992;Szabó, 2001Szabó, , 2003Szabó, , 2008. Ineffectiveness of GnRHa for induction of pike ovulation might be associated with low doses of GnRHa (up to 50 µg kg -1 ) or use of emulsified GnRHa without adjuvants.…”

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“…In the two treatment groups females received an injection of a crude preparation of dried common carp or silver carp pituitary, respectively, at a dose of 3.5 mg kg -1 BW. Pituitaries were administered in a vehicle of a 2.5% aqueous dispersion of Carbopol resin (Szabó, 2008). Injections were applied intraperitoneally at a volume of 0.5 ml kg -1 BW.…”