WCS helps release juvenile whale shark from net in Indonesian marine park

WCS helps release juvenile whale shark from net in Indonesian marine park
On October 8th, WCS researchers and staff members of the Karimunjawa National Park in Indonesia responded to an unusual situation: a juvenile whale shark caught in a net set for anchovies and other small fish. Credit: Muhammad Jamaludin/Wildlife Conservation Society.

It's not every day that fishermen catch the world's largest fish species in their nets, but this is what recently happened in Indonesia's Karimunjawa National Park, according to the Wildlife Conservation Society.

While catching anchovies and small bait fish in a stationary net off the coast of Java on October 8th, a group of fishers discovered a much larger animal in their lift net—a juvenile measuring four meters in length (more than 13 feet). The fishers were then able to quickly alert staff members from the Karimunjawa National Park Authority and WCS using a text message system first established for reporting fishing violations.

"Whale sharks have not been common in these waters over the past decade, so the appearance of this animal in a coastal net is a surprise," said Stuart Campbell of WCS's Marine Program. "Fortunately, the SMS (Short Message Service) set up to report fishery violations enabled rangers from the service and WCS to respond to this accidental incident fast enough to release the animal."

Staff members from both the park authority and WCS arrived at the scene in the early morning after receiving texts from the fishers, who were both concerned about the possibility of getting in trouble for inadvertently catching the shark and unsure of how to release it. The whale shark was released soon after.

Campbell and other members of WCS's Indonesia Program think the presence of the shark may indicate the ecological recovery of Karimunjawa waters due to changes in fishing regulations. Over the past three years, a series of no-take reserves have been established as well as a total ban on destructive trawl nets that destroy seabed habitat in coastal areas, both of which have led to a boost in local fishery production.

With training from WCS and RARE, fishers now use the SMS "hotline" to report fishing violations and marine animal strandings to park authorities instantaneously. The innovation has led to a remarkable increase in compliance with fishery closures throughout the park. The new system has also led to the prosecution of illegal trawl fishing by the park authority, that has previously decimated local fish populations. Data from WCS and government agencies now show a 50 percent increase in local fish populations over the past three years, which in turn is bringing whale sharks back into the area most likely due to the increase in prey, which can include plankton, small fish, and fish eggs. The whale sharks occur in Karimunjawa National Park from September to November, a period that coincides with high local fishery production.

"Using texts to respond to fishing violations and strandings has greatly increased the efficiency of regulatory enforcement in Karimunjawa," said Dr. Caleb McClennen, Director of WCS's Marine Program. "This low-cost system is helping to bring ecological balance back to the coastal waters of Java and is boosting fishing productivity as well."


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Citation: WCS helps release juvenile whale shark from net in Indonesian marine park (2013, November 14) retrieved 31 March 2020 from https://phys.org/news/2013-11-wcs-juvenile-whale-shark-net.html
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