The lsraeli Joumal of Aquaculture - Bamidgeh 49(4), 1997, 214-221

ACCELERATION OF GONADAL DEVELOPMENT AND SPAWNING
INDUCTION IN THE MEDITERRANEAN GREY MULLET,
MUGIL CEPHALUS: PRELIMINARY STUDIES


David de Monbrisoni¹, Itai Tzchori ¹,³, M. Claire Holland², Yonathan Zohar², Zvi Yaron³ and Abigail Elizuri

1 The National Center for Mariculture, Israel Oceanographic and Limnological Research, POB 1212, Eilat 88112, Israel. e-mail: elizura@agri.huji.ac.il

2 Center of Marine Biotechnology and Maryland Agriculture Experiment Station, University of Maryland, Biotechnology Institute, Baltimore, MD 21202, USA. e-mail: zohar@umbi.umd.edu

3 The Norman and Rose Lederer Chair of Experimental Biology Department of Zoology, Tel Aviv University, Tel Aviv 69978, Israel, e-mail: yaronz@ post.tau.ac.il



(Received 12.6.97, Accepted 7.12.97)

Abstract

Grey mullet brood stock, maintained under a shifted photoperiod, were treated with controlled- release hormonal devices to accelerate gonadal development and subsequent spawning. The females received testosterone and a superactive GnRH analogue (GnRHa) given via slow-release devices (microspheres). The males received 17ct-methyltestosterone via microspheres. Once oocytes reached the diameter of >500 nm, females were induced to spawn with OtH-calibrated carp pituitary extract followed 24 hours later by GnRHa administered via a sustained-release implant. The females were allowed to spawn in the presence of males. An average of 4.4 million eggs was obtained from each female, and the fertilization rate ranged from 20% to 98%.


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