Monosex male production in finfish as exemplified by tilapia: applications, problems, and prospects

Abstract

The use of monosex fish is intrinsically desirable in a variety of fish species in a range of aquaculture production systems. The potential advantages sought from their use may include one or more of the following features: achievement of higher average growth rate, elimination of reproduction, reduction of sexual/territorial behaviour, reduction of variation in harvest size, and reduction of risk of environmental impact resulting from escapes of exotic species.Fish as a group have systems of sex determination which are of considerable biological interest and significance for studies in evolutionary biology. However, they are very variable, relatively poorly understood and give rise to much variation in sex ratio between, and within, species. Enough is known, however, to enable us to say that these systems are often employed in ways which sharply distinguish the fishes from groups such as mammals, birds and reptiles. As a consequence, manipulations of sexual phenotype designed to produce monosex populations are not straightforward and the results are not necessarily predictable. This paper reviews the techniques for production of monosex males, and considers in detail the case of the Y Y / G M T technology in the Nile tilapia, which is the only example of a genetic technology for the production of monosex males so far widely adopted by the aquaculture industry. The considerable benefits accruing from the use of GMT are described. An attempt at projecting future developments in this area of aquaculture is made. 0 0 4 4 -8 4 8 6 / 0 1 / $ -see front matter ©2001 Elsevier Science B.V. All rights reserved. PII: S 0 0 4 4 -8 4 8 6 ( 0 1 ) 0 0 5 9 0 -7 284 JA. Beardmore et al / Aquaculture 197 (2001) 283-301

Efficacy of Basella alba and Tribulus terrestris extracts for production of monosex Nile tilapia, Oreochromis niloticus

“…Interestingly, during treatment with B. alba leaf extracts for all the solvents, the highest treatment concentration of 1.5 gm/kg produced the lowest percentage of males among the different treatment categories in the present study (Table 2). Reduced masculinisation and paradoxical feminization has been observed in fish treated with high concentration of synthetic steroids as well (Beardmore et al, 2001;Devlin and Nagahama, 2002). Dietary inclusion of commercially available T. terrestris extract at a concentration of 2.5 gm/kg basal diet have resulted in 84 % male population in O. niloticus (Omitoyin et al, 2013).…”

Particularities of reproduction and oogenesis in teleost fish compared to mammals

“…Finally, in tilapias, where male monosex populations are preferred for farming, these can be obtained by crossing normal females with "neo-super males" of genotype YY. These, which are viable and functional, are obtained by crossing normal XY males with neo XY females resulting from estrogenic treatment of normal fry [156].…”

A New Natural Autotetraploid and Chromosomal Characteristics of Dwarf Snakehead Fish, <i>Channa gachua</i> (Perciformes, Channidae) in Thailand

“…These studies are also an important step towards the establishment of genetic improvement techniques involved in chromosome manipulation techniques, including inter-or intra-species hybridizations, sex control, gynogenesis, androgenesis and induction of polyploidy (Wu et al 1986, Diter et al 1993. These genetic techniques have been widely applied to improve farmed stocks in many aquaculture species in the world (Arai 2001, Beardmore et al 2001, Dunham 2007, Chai et al 2009). …”