Rescuing tuna fish with Titanium
Testing material from ThyssenKrupp Titanium supports the environmental project “REPRODOTT”
When a diver dives into the giant underwater cages of one of the numerous “tuna fish ranches” in the Mediterranean sea with his so called spear gun implant, titanium is essential. Because the tip of his harpoon with which the implant is set beneath the skin, originates at ThyssenKrupp Titanium’s Essen plant. What is the purpose of the project in which animals living in captivity are injected an implant with a spear gun? What is initially read like an abstract from a story about tuna fishing is in reality the opposite. In the last years the population of the red tuna fish and the blue fin tuna fish (Thunnus Thynnus) decreased so extremely by fishing that their worldwide existence is in danger. To prevent the blue fin from being extinct a team of international scientists devised a method for their rescue.
With the help of harmless hormones for both fish and man the biologists and zoologists are accelerating the reproduction at the fish ranches. This is an important step in the controlled reproduction of tuna fish. The goal of the REPRODOTT project that is subsidized by the European Union with 1.5 million Euros is to save the tuna fish population. REPRODOTT stands for “REPROduction and Domestication Of Thunnus Thynnus”. The reproduction of tuna fish in captivity means an enormous relief for the natural population that can recover in the next years.
“Of course we are especially glad to support such projects,” says Dr. Heinz Sibum, manager of research and development at ThyssenKrupp Titanium. “Our material is especially suited for applications in biology because of its hardness and its lack of side effects. And if we can contribute to environmental protection. Professor Christopher Bridges from the Düsseldorf University shares this opinion. Together with his six-member team he developed the precision instruments for the injection of the hormones at the institute for zoo physiology. It became apparent quickly that the previously used steel tips did not withstand the extreme strain of the injection process.
“It is a great challenge for the divers to place the implant at the correct spot,” Bridges describes the under water process. After all a full-grown tuna fish is a big animal. “We are talking about a length of up to 2 meters and a weight of up to 200 kilograms in motion.” Retaining the animals and keeping them away from water for a short time is too much stress for them and would be very complex. “With a quick agitation the diver hits the tip behind the vertical tail fin so that the tuna fish doesn´t get hurt. Because the animals react to the painless contact and drift off we need “jabsticks” for the tips of the harpoons that are made of a hard and at the same time compatible material. Titanium is just the right thing. The formerly used steel tips always paid tribute to the power of the tuna fish and got twisted.”
Titanium is suited better than steel. On one hand the inserted tag contains the hormone responsible for premature spawning and on the other hand a code for the marking and identification of the fish. At the same time the biopsy needle at the tip can extract a muscle sample during tagging, “which gives us the possibility to verify the physical condition of the fish,” Bridges explains. “The work of the divers seems more simple than it is. Sometimes he has to stay under water for 3 minutes to catch the right moment. And all that without oxygen.”
That the research efforts of professor Bridges, his team and the Heinrich-Heine-University are worth it is documented by the obtained results and by the signing of contract with one of Australia’s most significant tuna fish breeders.Because even in Down Under the breeding processes and the increase of the tuna fish population are of interest.