Experts of the University of Cádiz control the change of sex in gilthead breams with microchips

With this study, experts of the lab observe these changes first hand thanks to a microchip. ‘We implant it in the dorsal muscle of the specimens we are analysing, which is like their id card, as gilthead breams have a peculiarity- they change sex as they grow. The change of sex from male to female can happen once they reach one and a half kilos of weight. With this system it is easy to know what fish we are checking. Once each specimen is identified, we weight and measure it in order to follow their development, as mature fish get very fat due to their gonads, but do not get very long during the laying period’, director of Plant of Marine Cultures Rosa Vázquez said.

In order to guarantee the well-being of the different species in this animal experimentation lab, fish are kept in such conditions so as to avoid stress. ‘These factors include the diminishing of the light intensity. In the specific case of breeding plants of gilthead breams, the fish of the facilities are kept in tanks of sea water with a light control system. Also, they are subject to a controlled photoperiod of 8 hours of daylight’, the lab’s head technician said.

In addition to following-up the changes of fish in captivity, the obtaining of eggs and larvae allows to carry out trials and larva culture practical in the lab.

A decade of research in Aquaculture

Apart from coordinating and managing the teaching and research activities of the University of Cadiz in the field of Aquaculture, the Plant of Marine Cultures breeds, supplies and experiments with marine species. Its function as a university lab does not exempt it from being a place where research projects are carried out.

Coordinated by Dr. María del Carmen Rendón, of the Department of Biology, and led by Rosa Vázquez (head technician since 1996), the team of experts is made up by Ana Álvarez Macías, Carmen María Álvarez Torres, Mariano García de Lara and Rosario Sánchez Maestre. However, the lab is also a place for training the future professionals of the aquaculture sector. This is why there are also two university scholarship holders, trainees at a company, and students doing practical work on aquaculture operations at the vocational training centre ‘Santi Petri’ of San Fernando, who are learning the latest techniques and novelties in this sector.

The team develops techniques for fish and mollusc breeding, larvae cultures of fish and molluscs, and phytoplankton and zooplankton cultures. ‘We produce biological material related to marine cultures, such as zooplankton (rotifers and artemiae), phytoplankton, with a camera of microalgae culture, as well as eggs and larvae. All these cultures are useful for teaching and research at the Faculty of Sea and Environmental Sciences’, Rosa Vázquez said.