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Aquaculture CRSP 21st Annual Technical Report
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33
Broodstock Diets and Spawning of Colossoma macropomum and/or Piaractus brachypomus

Tenth Work Plan, Feeds and Fertilizers Research 2 (10FFR2)
Final Report

Konrad Dabrowski and Jacques Rinchard
The Ohio State University School of Natural Resources
Columbus, Ohio, USA

Fernando Alcantara and Salvador Tello
Instituto de Investigaciones de la Amazonia Peruana
Iquitos, Peru

Abstract

Hormonal treatments were used to induce final maturation, ovulation or spermation in male and female gamitana (Colossoma macropomum) and pacu (Piaractus brachypomus). Plasma sex steroid hormone levels were also assessed prior to and after the hormonal treatments to better understand the process of induced spermiation or ovulation. The results of this study indicated that male gamitana and pacu responded positively to the hormonal treatments. In 2001, the concentrations of plasma sex steroids (estradiol-17 and testosterone) significantly increased after the hormonal injections whereas the levels of 11-ketotestoterone remained constant. In contrast, female gamitana (2001 and 2002) and pacu (2002) did not undergo final maturation/ovulation. The increase of estradiol-17 (E2), as well as the non-detection of 17,20 -dihydroxy-4-pregnen-3-one (17,20 P) indicated that females were not ready to spawn when they were injected.

Introduction

Gamitana (Colossoma macropomum), pacu (Piaractus brachypomus) (Amazon drainage) and red belly pacu (P. mesopotamicus) (Parana River drainage) are becoming important species for aquaculture in South America (Saint-Paul, 1992; Roubach et al., 2003). Moreover, C. macropomum has been reported by the US Department of Agriculture (Situation and Outlook Report, USDA 1993) as a species of potential importance to US aquaculture.

Studies on artificial reproduction of pacu clearly indicated that this species has a synchronous type of oocyte development (Godinho and Gohindo, 1986; Romagosa et al., 1990). Spermiation and ovulation were induced with either human chorionic gonadotropin (hCG) or carp pituitary extracts (CPE). However, the success of final maturation and quality of the gametes obtained varied depend on treatment, and possibly of fish size. Females of 1.4 and 1.8 kg were used in the previously mentioned studies, however an increase of size to 3.5 0.8 kg increased the rate of egg production and fertilization to 96% and 82%, respectively (Zaniboni Filho and Barbosa, 1996).
Only recently the first data on steroid concentrations in blood plasma of pacu became available (Gazola et al., 1996;
Gazola and Borella, 1997). This information in association with induced spawning can considerably improve the understanding of the final maturation and possibly allow the controlled reproduction of this species outside of their range of distribution.

Therefore, the objective of this study was to compare spawning performance and annual cycles of blood plasma steroid concentrations for
Colossoma and/or Piaractus broodstock.

Methods and Materials

On 13 November 2001, gamitana (Colossoma macropomum) were obtained from a stock of mature fish raised in a 1.2 ha pond (10C) at the Instituto de Investigaciones de la Amazonia Peruana (IIAP). Average weights (mean SD) of males and females were 6.82 0.81 kg and 9.34 0.89 kg, respectively. Four pairs of gamitana were moved into concrete indoor 0.75 m3 tanks. In each tank, the male was separated from the female by a net. Both genders were injected with two doses of Conceptual (luteinizing hormone releasing hormone analog, LHRHa). The concentration of preparation was 0.0042 mg of equivalents of active hormone per ml. Males and females were injected intraperitoneally with 1