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FISH ENGINEERING

Robust hybrid

The tilapia resulting from the cross-breeding of the mutant red tilapia with the wild black tilapia grows quickly in captivity

alexandre HilsdorfHybrid offspring produced from the Chitralada tilapias (above) and Red Stirlingalexandre Hilsdorf

A tasty, well developed, reddish hybrid fish was obtained after four years of hard work involving the genetic improvement of two varieties of the Oreochromis niloticus tilapia, one of them a red mutant and the other a black wild tilapia. “We performed cross-breeding, followed by selection, and produced a hybrid ready to compete in the market,” says professor Alexandre Wagner Silva Hilsdorf, from the Núcleo Integrado de Biotecnologia, Biotechnology Center, of the University of Mogi das Cruzes (UMC). Professor Hilsdorf is the coordinator of the project in partnership with the Royal Fish company from the city of Jundiaí, inland São Paulo State. The red variety is a mutant of the wild black tilapia, a native of the Nile River in northeast Africa. The red mutant was developed in the early 1990’s by researchers from the Aquaculture Institute at Scotland’s Stirling University, who named the new variety the Red Stirling. “The main characteristic of this mutant tilapia is the absence of black pigmentation on the skin. But this is not an albino fish, because it has the black pigment cells, called melanophores, on the internal organs and eyes,” Hilsdorf explains.

Although this fish attracts consumers because of its appearance and taste, it has one drawback for those who raise the fish – it grows less than the other varieties of genetically improved tilapias, such as, for example, the Chitralada variety, developed in Japan and improved in cultivation tanks in the royal palace of Chitralada, in Bangkok, Thailand. This variety was introduced to Brazil in 1996, thanks to the donation of fish larvae by Thailand’s Asian Institute of Technology. At present, this variety is the most used commercially. The proposal of the project funded by FAPESP under the Pesquisa Inovativa em Pequena Empresa/Pipe, Innovative Research modality, was to combine the best characteristics of each variety, namely, the reddish coloring of the Red Stirling and the big size of the Chitralada in a short period of time. “Any breeding involves the need for the given animal to grow as quickly as possible in the shortest period of time so that the breeders do not undergo losses,” says Hilsdorf, who has a degree in zoo technology from the Federal University of Lavras, in the State of Minas Gerais. “Until a short time ago, the commercial weight of the tilapia corresponded to 500 grams. This weight was reached within five months at an average temperature of 25 degrees Celsius in the water,” says the researcher. But the market has changed and wants tilapias weighing 700 to 800 grams. The reddish hybrids obtained from the cross-breeding weigh up to 700 grams, 30% more than the Red Stirling variety and 6% more than the Chitralada variety.

alexandre HilsdorfFish farming tanks at the Royal Fish company in Jundiaíalexandre Hilsdorf

Commercial variety
Prior to the field experiments, Hilsdorf performed a number of tests to evaluate the Red Stirling’s potential in the composition of a hybrid variety with the Chitralada. “Up to that time, the red mutant had not undergone any kind of genetic improvement,” says the researcher. Although the Red Stirling was smaller than the Chitraladsa and weighted 30% less, Hilsdorf noticed that it had an advantage in comparison to other varieties of red tilapia. “The cross-breeding of the Red Stirling with the black variety almost always resulted in red hybrids,” he says. This characteristic was crucial to move forward with the project, because the original proposal had been to obtain a commercial variety that could compete in the market with a variety of tilapia commonly known in Brazil as Saint Peter, an orange-colored hybrid introduced in Brazil by an Israeli company, Aquaculture Production Technology. This was the researcher’s argument to convince ear, nose and throat doctor Ricardo Ferreira Bento, one of the three partners of Royal Fish, to travel to Scotland to purchase 1.200 larvae of the reddish variety. At the time, the company was breeding the Saint Peter variety, but was constantly obliged to buy new matrixes from the Israeli company.

The partnership between Hilsdorf and Royal Fish started with Ricardo Bento’s visit, in 1999, to professor José Eduardo Krieger, director of the Laboratório de Genética e Cardiologia Molecular, Genetics and Molecular Laboratory at the Instituto do Coração, Heart Institute in São Paulo. Krieger had been the advisor of Hilsdorf’s doctorate thesis on the genetics of the mitochondrial DNA of a species of fish living in the Paraíba do Sul River basin. “The bulletin board had an article I had written about fish, which attracted Ricardo’s interest,” says Hilsdorf. From then on, the exchange of knowledge and common interests grew stronger. At present, the genetic improvement research is following new pathways, with new cross-breeding techniques involving red and black tilapias. “Now we are working on a genetic improvement program with the red variety and other black varieties besides the Chitralada, with cross-breeding and progeny tests in order to obtain an even better red tilapia,” the researcher explains.

In addition to the Chitralada, this research project is also testing the response of a variety of tilapia called Gift, the acronym for Genetic Improved Farmed Tilapia – Oreochromis niloticus, a genetic improvement project developed in the Philippines with the collaboration of Norway, to obtain a highly productive tilapia for social purposes in Asia. The effort to obtain new, resistant, highly productive varieties with differentiated meat has an explanation. “The tilapia is intensively farmed in Brazil,” says Hilsdorf. “Production totals approximately 100 thousand tons a year. This is not bad for a fish that came to Brazil in the 1950’s to control weeds growing inside the turbines in hydroelectric power plants.”

Differences between octopi

Octopi found on the South and Southeast coast belong to the Octopus vulgaris species, while the ones found on the North and Northeast coast belong to the Octopus insularis species.

Their eight tentacles make all the octopi living on the Brazilian coast seem to be the same. Genetically, however, they can be very different, as observed in a doctorate study conducted by Ângela Aparecida Moreira, at the University of São Paulo’s post-graduate program in Biotechnology. The experimental part of the study was performed at the Laboratório de Genética de Organismos Aquáticos e Aquicultura, Aquaculture Lab, at the University of Mogi das Cruzes. Professor Alexandre Hilsdrof was the advisor of the study. “A more detailed analysis shows that the common octopi, known as Octopus vulgaris, are more concentrated in the South and Southeast, while the octopi living in the North and Northeast belong to another species, recently identified as the Octopus insularis, because of an octopus found on the island of Fernando de Noronha,” Hilsdorf explains. The octopus caught by fisherman off the South and Southeast coasts is genetically similar to the octopus found in Portugal, called Octopus vulgaris. This kind of knowledge is important for future work involving conservation and re-population and for the control of predatory fishing. Researcher Acácio Ribeiro Gomes Tomás, from the Instituto de Pesca de Santos, Fish Institute, participated in the study. He collected the octopi for the study. “Our proposal was to conduct a study focused on the population genetics, and to this end, we had to know if the population of the captured octopi on the Brazilian coast were part of the same genetic group or were genetically different,” says Hilsdorf. The analyses were performed with micro-satellite markers, the same DNA markers used to test paternity. “That was when we noticed that the octopi on a beach close to the city of Recife, on the coast of the State of Pernambuco, were less similar to the octopi found on the coast of the State of Santa Catarina,” he reports.
The existence of two different species was confirmed by another genetic approach, namely the comparison of sequences of stretches of the mitochondrial DNA.

The projects
1.
Genetic and zootechnical evaluation of two varieties of Nile tilapia for the establishment of the mass production of a hybrid (nº 01/08416-4); Modality Pesquisa Inovativa em Pequena Empresa/Pipe Program; Coordinator Alexandre Wagner Silva Hilsdorf – UMC; Investment R$ 123.642,39 e US$ 8.998,66 (FAPESP)
2. Fish biotechnology applied to genetic evaluation of the population of octopi (Octopus vulgaris) stocks on the Brazilian coast by means of micro satellite markers for sustained management (nº 04/02631-9); Modality Regular Research Awards; Coordinator Alexandre Wagner Silva Hilsdorf – UMC; Investment R$ 69.313,67 (FAPESP)

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