The fate of the turtle – who was rescued, monitored and travelled thousands of kilometers only to apparently get trapped again – exemplifies the threats faced by these marine animals

Zafrir Rinat Jun. 23, 2021

Thunderbird the sea turtle
Thunderbird the sea turtle

At least seven environmental protection agencies and research institutes along the Mediterranean coast and Europe came to the rescue of a brown female sea turtle who was in distress in the Mediterranean last year.

It appears that the turtle, rescued from a fishing net, managed to make it all the way to West Africa only to perish apparently after being caught in another fishing net, joining thousands of others that meet the same fate every year.

Last year, members of Save the Med, which operates in the western Mediterranean, found a brown female sea turtle caught up in a discarded fishing net near Majorca. Such nets, abandoned or lost at sea, are called ghost nets. The turtle was taken for medical treatment at a center for saving animals on the island, where staff freed her from the net and treated her wounds.

Dubbed “Thunderbird” by members of the center, she was returned to the sea last August with a satellite-linked transmitter attached to her in order to track her movements. The turtle swam westwards, towards the Strait of Gibraltar and entered the Atlantic Ocean, where she began a journey spanning 6,000 kilometers (almost 4,000 miles) , reaching the coast of Senegal in western Africa.

The last signal emitted by Thunderbird came three months ago, followed by silence. “It’s always challenging to figure out what caused transmission to stop, so we decided to investigate possible causes,” says Dr. David Marsh from the University of Exeter in Britain, which is collaborating with the University of Barcelona in a study of sea turtles.

Thunderbird the sea turtle
Thunderbird the sea turtleCredit: Miquel Gomila

“After concluding that the battery and sensors were functioning, we went to an information portal that tracks the movement of fishing vessels. We saw that the last activity of Thunderbird was close to an area in which fishing boats were active. We assume that the turtle was accidentally entangled in a fisherman’s net and taken to a port. We don’t know if it was released or died after being caught.”

All attempts to locate Thunderbird with the help of environmental groups in Senegal were to no avail so far. “The epic journey of this turtle exemplifies the two greatest threats faced by marine animals,” notes Marsh. “The first is entanglement in ghost nets and the second is accidentally being caught in nets laid out by commercial fishermen. We need to urgently deal with these threats.”

International groups are trying to promote the use of nets that would prevent larger animals from being caught in them. There are also efforts to impose limits on fishing in areas in which there are large concentrations of marine mammals and turtles and to boost awareness of fishermen to the dangers of large mammals being caught up in their nets. These groups also try to get fishermen to remove nets that are no longer in use from the water.

The Mediterranean has a permanent population of two types of sea turtles, the brown and the green species, both of which are considered protected species in Israel. The brown ones often go on journeys spanning thousands of kilometers, since they wander between several seas. According to a report published last year by an international organization for environmental protection, tens of thousands of turtles are caught by nets every year, almost half of these not surviving the ordeal. There are estimates that near the coast of Cyprus, a major focus of turtle reproduction, one thousand turtles are trapped by nets each year.

A survey conducted last year by environmental groups in a nature reserve near the coast of Spain illustrates the scope of the problem. The survey found a hundred phantom nets or special devices for catching fish, which included lines with hooks and bait. These devices trapped a whale and a brown turtle, both of which died. Another turtle was extricated alive.

Thunderbird the sea turtle
Thunderbird the sea turtleCredit: Miquel Gomila

As part of Israel’s efforts to protest both brown and green turtles, the Nature and Parks Authority runs a multi-year program, which includes protection of nests and the establishment of a rescue center at the Mevo’ot Yam school in Michmoret. The center treats injured turtles, including ones that became entangled in nets and later releases some of them into the sea.

There are no accurate numbers regarding the harm to turtles along the coast of Israel, but there are at least a few dozen casualties a year. In recent years there has been a change in the environmental protection of marine life, after limits were imposed on fishing with nets, which is the major cause of harm to turtles.

However, there is not much progress in Israel with regard to establishing marine nature reserves. These are an important means for protecting marine life, since fishing can be totally prohibited in such reserves. Marine areas close to Israel are not major fishing grounds, so that harm caused by nets is less than in other areas.

Last week, a brown turtle called Tanga was released to sea, after being found injured four months ago. It was treated at a rescue center in central Israel. Rescuers hope that its fate is better than that of Thunderbird, a turtle that once lived at the other end of the Mediterranean.