"The sharks were accidentally trapped by fishermen, and we took care of them for few months. After they grew stronger, we released them back to the sea," a local resident, Yoki Sinugroho, who joined a local environmental group, said.
Yoki and his group have called on local fishermen, who accidentally caught the endangered fish with their net, to release them.
They also called on fishermen to be concerned about the marine ecosystem, as damaged ecosystem would affect their catch.
"We have seen some endangered species, including these sharks, sold at a cheap price. It would be better if we bought them, took care of them, and released them to the sea," he added.
The blacktip sharks were 30-40 centimeters in length when they were captured by the fishermen. Now, they have grown to 80 centimeters, Yoki said, adding that they were strong enough to survive in their habitats.
Normally wary of humans, blacktip sharks could become aggressive in the presence of food and have been responsible for a number of attacks on people.
On the basis of its low reproductive rate and high value to fishermen, these sharks have been categorized as Near Threatened species by the IUCN.(*)