Istanbul - (AFP) - Fishermen on the banks of the Bosphorus Strait put down their fishing rods and crossed their hands, with frustration evident on their faces as they looked at a fishing boat hauling its huge nets in the water with a large winch.

“Come on, get out of here!” one of them shouts, as he waits impatiently for the boat to depart so that he can once again practice fishing in the Bosphorus waters.

"I've been here since six in the morning, but this boat threw its fishing net in front of us, which prevented us from carrying out our activities," said Mehmet Dogan, who only caught one 40-centimetre bonito fish.

This period is the season for bonito fish, one of the famous types of tuna, in the waters of the Bosphorus.

Ships cast nets of more than 1,000 meters across the strait, limiting the opportunity for amateur fishermen like Muhammad to catch fish.

"This place is the entry path for fish that will not have enough time just to lay their eggs," says Murat Ayhanoglu from Kirchburnu Bay, where a ship docks from which the sound of its crew can be heard pulling the heavy fishing net.

"When these ships are here, it is certain that we will catch very little," the man in his fifties adds with displeasure, pointing to fish species that are witnessing a decline in their numbers and becoming rare, such as shakhura, anchovies, bonito and blue fish. He stresses that "the authorities must find a solution to this issue."

Saadat Karakulak, a professor at the Faculty of Aquatic Sciences in Istanbul, points out that the volume of fishing in the Bosphorus decreased over a few years from about 500 or 600 thousand tons annually to 328 thousand tons, which constitutes "evidence of a decrease in the number of fish."

As for the authorities, they resorted to a strange idea, proposing at the beginning of the month to close the Bosphorus to traffic for half a day, with the aim of allocating its waters to fishing vessels and industrial ones.

The Ministry of Transport reversed its decision after protests from scientists and NGOs denouncing what it called a "fishing race in a vital corridor" of great importance.

Bayram Ozturk, director of the Department of Marine Biology at Istanbul University and the TODAF Foundation, which specializes in marine research, sneers, saying, "On November 6, killing was permitted."

"This cannot be done now, as the numbers of fish are in danger, and some of them have touched very low levels, such as sturgeon and swordfish," he added, adding, "We should think about how to preserve and sustain them."

He considers that the time has come to restrict the fishing of certain types of fish to certain proportions.

This year, anchovies are in danger because the bonito, which is present in large quantities, is feeding on them. Ozturk explains that the high bonito numbers are attributed to the COVID-19 pandemic, during which the fishermen were quarantined.

He points to other threats to fish, including plastic waste, urban pollution and heavy marine traffic.

The Bosporus is one of the most active straits in the world, with more than two hundred cargo ships and tankers passing through it daily from the Caspian Sea, in addition to dry bulk carriers such as those carrying grain from Ukraine.

Ozturk explains that "the width of the strait at its narrowest point does not exceed 760 meters," calling for "management of the situation at the regional level, as the fish spawns on the Ukrainian side and swims towards Turkey and the Mediterranean," and is eaten in Greece.

Serkan Karadeniz, whose boat is anchored in the port, is waiting for the bay to be emptied of ships to start fishing. And the captain followed the bonito from the Black Sea.

Karadeniz, who comes from Samsun on the Black Sea (north), resides in Canakkale, which borders the Aegean Sea.

The fisherman, who switched this year to bonito fishing while he usually fished anchovies, notes that "the competition is strong, with more than 300 fishing vessels."

Erdogan Kartal, 60, explains that "the months of October and November record a large migration towards the Sea of Marmara and the Aegean," noting that he has been fishing since his childhood. And being the head of a guild that includes 34 entities, he deals with two thousand fishermen.

"The fish have decreased in size and are getting smaller and smaller," he says. "We catch fish that haven't spawned yet, which is dangerous."

"We no longer see the beautiful mackerel that existed in the past," he continues.

In his opinion, restrictions should be placed on catching certain sizes of fish and determining the numbers that are allowed to be caught. "We have to make some sacrifices, and if we let the fish pass, it will return," he says.