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Improving production efficiency of sea bass farming by developing methodologies to eliminate environmental androgenesis

The purpose of the PROBASS project is to address the problem faced by the sea bass aquaculture, which is that under culture conditions most of the fish (70-99%) are males. In addition, males grow slower than females and weigh up to 40% less at harvest, which reduces their market value, or they need to be cultured for longer, which increases production costs. PROBASS intends to develop methods of controlling sex differentiation to reduce unwanted males and increase females. Since environmental factors can influence sex ratios in fish, including the sea bass, PROBASS will investigate hormonal, biochemical and molecular parameters to understand the regulation of sex differentiation, and develop an environmental, hormone-free, feminisation protocol based on temperature, and density manipulations. Female-dominant stocks will result in more efficient production and increased profitability for the aquaculture of sea bass.

The overall objective of Probass is to understand the mechanisms regulating sex differentiation in cultured sea bass in order to develop methodologies to minimise the proportion of males in cultured stocks.
The first objective of Probass is to perform a temporal evaluation in sea bass
during the period encompassing sex differentiation in order to understand which sex
differentiation genes, brain and pituitary hormones, key steroidogenic enzymes, sexsteroid receptors, sex-steroid hormones or growth factors may be involved in the
regulation of sex differentiation in males and females.
The second objective of Probass is to manipulate the environment (temperature and
density) during critical periods in early development in order to reduce or eliminate male
dominance in cultured sea bass, and to determine which regulators of the sex
determination pathway - sex differentiation genes, steroidogenic enzymes, steroid
receptors, hormones or growth factors - are being influenced by those conditions. This
understanding will facilitate the development of a practical procedure, easily employed by
the EU aquaculture industry, to eliminate environmental androgenesis.

1. Production of male- and female-dominant stocks by selective grading.
2. Study the brain-pituitary-gonadal axis during sex differentiation and understanding the role of key components on this axis in relation to age, size and sex.
3. Study of how and when temperature and density affect sex differentiation, and
production of female-dominant stocks.
4. Development of a novel method based in the manipulation of these environmental
factors and trials of this method in production facilities to test usefulness.


Scientist responsible for the project

Ribera de Cabanes
12595 Castallon
Spain - ES

Phone: +34 964319500
Fax: +34 964319509


Project ID QLRT-1999-31365
Organisation Spanish Council for Scientific Research - Instituto de Acuicultura de Torre de la Sal
Area 5.1.2
Start date 01 October 2000
Duration (months) 36
Total cost 2 262 148 €
Total EC contribution   1 360 000 €
Status Unknown

The partners

  • Universidade do Algarve - Centre of Marine Sciences, Portugal - PT
  • University of Wales - Cardiff School of Biosciences, United Kingdom (The) - GB
  • The National Center for Mariculture, Israel Oceanographic and Limnological Center of Marine Sciences, Israel - IL

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