Reseacher Luis Jorge García Márquez, a professor and researcher at of the School of Veterinary Medicine and Zootechnics of the University of Colima

How to avoid tilapia mortality investigated

MEXICO
Tuesday, October 23, 2018, 01:50 (GMT + 9)

The University of Colima, in coordination with the universities of Guadalajara and the National Autonomous University of Mexico, is developing a scientific project on aquaculture health to identify and diagnose diseases, with the aim of reducing mortality impact and achieving greater tilapia survival.

Researcher Luis Jorge García Márquez, a professor-researcher of the School of Veterinary Medicine and Zootechnics (FMVZ) of the University of Colima in Tecomán, highlighted that farmed tilapia production has increased considerably in the last ten years, and is considered in second place as to production only after the shrimp.

But he also pointed out that Mexico has been diagnosed with several re-emerging diseases of tilapia, which cause mortalities of between 35 and 90 per cent. Two of these diseases are of bacterial origin: francisellosis, which affects fish in the breeding and pre-fattening stages, and streptococcosis, which affects fish in pre-fattening and fattening stages.

                         

There is also another disease caused by a virus of the family Orthomyxoviridae, known as lake tilapia virus (TiLV) disease, which occurred in Mexico just this year and can cause a mortality close to 90 per cent in these fish.

Professor García commented that he has been doing research on this topic for some time. In a first stage, some diseases of viral, bacterial and parasitic origin were diagnosed in several tilapia production farms in Mexico and Central America, and in a second stage the epidemiological study of these diseases was carried out.

Currently, he said, "we are working on aspects of preventive medicine (treatment, vaccine and biosafety), animal welfare, bioethics, sustainability and care of the environment to make the aquaculture production system more profitable."

He indicated that in these intensive production systems floating cages (18 metres in diameter and 8 metres deep) are used in rivers or dams, with a density of 60,000 to 80,000 fish in the fattening phase. "This causes them a state of chronic stress and, coupled with poor water quality, poor nutrition, the presence of parasites and bacteria, mortality and considerable economic losses occur," he explained.

He commented that the way to combat this problem consists of prevention: to lower the density, move the cages to where there is greater transit of water, and make water replacements that lower the temperature so that the fish do not get stressed.

He pointed out that the diseases studied are involved in 30 and 35 per cent of the mortality of these fish, so if the research work is carried out and corrective measures are taken, mortality can drop to 5 and 3 per cent.

Finally, he pointed out that this type of projects helps to link students and thus create academic products such as theses, papers and scientific articles. The important thing "is the training of the students so that they can settle into jobs when they graduate", concluded the researcher.

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