The sea beasts burst through steel strong nets at not one but two salmon farms.
Last week there was two incidents in Western Norway involving different tuna according to the Norwegian Directorate of Fisheries.
A cage owned by Austevoll Melaks, at Austevoll close to Bergen, was hit by a 3m long blue fin tuna.
“They managed to catch it in a net and kill it,” said Leni Marie Lisæter, section manager at the Directorate.
The second company, K. Strømmen Lakseoppdrett, also in Western Norway, reported a hole in one of their nets on September 27.
“When we were there for an inspection on October 1st, we received a message that there was observed a shark-like fish in the net,” said Leni Marie Lisæter.
Apparently it was blue-fin tuna.
“We were out inspecting the cage, searching for why there was hole, but there no doubt about when we saw the 2.7 m long 275 kilo tuna swimming in the cage.”
The hole was 12m below surface, and it was 1m tall and 12 cm wide.
“We are worried about the development. Furthermore we know little about why tuna suddenly attack, going straight through the net and into the cages,” Leni Marie Lisæter said.
Strengthened with steel threads
K. Strømmen Lakseoppdrett have a net that is strengthened with steel threads and the tuna had injuries to its nose and face. Blue fin tunas can swim up to 70km/h and has a head thats covered by hard shell, making it easy for it to break through any net that has a resistance strength of around 95 kilos.
“The tuna that was also caught in the net. When they opened the stomach of the fish, it was empty; so the tuna had been in the cage for almost a week and didn’t appear to have eaten much salmon,” said Lisæter.
The fish was brought to the Institute Of Marine Research so its heavy metals, length, weight, and DNA could be analysed.