Mongabay-India

Tagging crocodiles with satellite transmitters

One of the four saltwater crocodiles in Bangladesh with a newly installed satellite transmitter, released into the wild. Image by Md Mofizur Rahaman Chowdury.
  • Bangladesh has started using satellite tags to monitor saltwater crocodiles in the country’s Sundarbans, marking Asia’s first such initiative.
  • Four crocodiles have been tagged to study their movements, habitat, and lifespan.
  • Experts say the data collected will play an important role in crocodile conservation in Bangladesh, where the species is critically endangered, and will help in creating conservation management strategies.

In a breakthrough in saltwater crocodile conservation in Bangladesh, the country has started using a satellite tagging system to monitor the species’ movements, habits, and life span in the Sundarbans mangroves in Bangladesh. This is perhaps the first time this has been done in Asia.

On March 13, Bangladesh Forest Department attached satellite tags on two saltwater crocodiles (Crocodylus porosus) and released them in the mangrove waters of the Sundarbans. A few days later, the same process was repeated on two more individuals.

Two Australian crocodilian experts — Ruchira Somaweera, research scientist at Australia’s Commonwealth Scientific and Industrial Research Organisation (CSIRO) and an adjunct lecturer at Murdoch University, and Paul Beri, principal ranger of Queensland Parks and Wildlife Services — assisted in tagging the crocodiles and trained the forest officials in tagging and monitoring.

The forest department team in Bangladesh and the experts from Australia stand next to a newly tagged crocodile before releasing it in the wild. Image by Md Mofizur Rahaman Chowdury.
The forest department team in Bangladesh and the experts from Australia stand next to a newly tagged crocodile before releasing it in the wild. Image by Md Mofizur Rahaman Chowdury.

Bangladesh’s forest department and IUCN Bangladesh are jointly implementing the project with support from the Integrated Management of the Sundarbans Mangroves and the Marine Protected Area (MPA) Swatch of No Ground in Bangladesh (SoNG), initiated by Deutsche Gesellschaft für Internationale Zusammenarbeit (GIZ), on behalf of Germany’s economy and development ministry.

Mihir Kumar Doe, Conservator of Forests (Khulna Circle), said there is a sizeable population of wild saltwater crocodiles in the Sundarbans currently as the forest department has released around 200 saltwater crocodiles to the mangroves since 2016 from its Karamjol Crocodile Breeding Centre in eastern Sundarbans.

“But we do not know the survival rate of the released crocodiles and whether the habitat is suitable for them,” Doe added.

He said that using the satellite tags, they are collecting data about the crocodiles’ habitat, range and lifecycle, adding that these data will continue to be helpful in crocodile conservation management in the future.

From the data of the four tagged saltwater crocodiles — one from the wild and three from captivity released into the wild — the researchers and the forest department officials aim to understand the species’ habits, identify their nesting hotspots, their ecology, mortality rate and habitat range, and collect data on human-crocodile conflicts.

ABM Sarwar Alam, program manager of IUCN Bangladesh, told Mongabay that one more wild crocodile will be tagged with a satellite transmitter soon.

Somaweera said that this project makes Bangladesh the first Asian country to deploy satellite tags on crocodiles and only the second in the world after Australia.

Alam said the U.S.-made satellite transmitters they’re using were specially manufactured considering the salty conditions and that they are providing data accurately every hour.

“The four crocodiles tagged with transmitters are absolutely doing well. Three are roaming in different rivers and canals of the Sundarbans but one crocodile went out of the mangrove forest, in Barishal. However, satellite data shows that it is now returning to the Sundarbans after travelling 150 kilometres [93 miles] in first 10 days,” he said.

Alam said the Bangladesh government has had no proper crocodile conservation plan right now and that the satellite data will play an important role in the reptile’s conservation. The home range of the saltwater crocodiles could be identified within one year after examining the data received by the satellite transmitters.

“Once we identify the home range and population of the crocodiles, the forest department will be able to prepare a proper conservation plan for the saltwater crocodiles,” he added.

A saltwater crocodile basking on the bank of a pond in Karamjol Crocodile Breeding Centre. Image by Md Mofizur Rahaman Chowdury.
A saltwater crocodile basking on the bank of a pond in Karamjol Crocodile Breeding Centre. Image by Md Mofizur Rahaman Chowdury.

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Threats to saltwater crocodiles in the Sundarbans

The population of wild saltwater crocodiles is decreasing due to growing anthropogenic pressure from tourism and the water transport system that passes through the core areas of the Sundarbans.

Commercial exploitation the crocodiles for their skins until the 1970s depleted the species’ population in Bangladesh. Under the Wildlife (Protection and Security) Act 2012, the saltwater crocodile is now a protected species in the country, but the remaining population faces a range of anthropogenic threats in the Sundarbans. Hunting remains a major threat to the crocodile since poachers are still active in the Sundarbans, according to a 2018 study.

The beekeepers of the Sundarbans returning home after collecting honey. Image by Jahidul Alam Nayan/Wikimedia Commons.
The beekeepers of the Sundarbans returning home after collecting honey. Image by Jahidul Alam Nayan/Wikimedia Commons.

Around 3.5 million local people enter the Sundarbans annually to collect fish, crabs, honey and non-timber forest products. The disturbance by the large number of resource collectors and cargo vessels navigating through different channels within the forest also disturb the crocodiles from basking in the sun.

According to IUCN red list 2015, which counted a small population of 100-150 mature wild individuals found in only a few estuaries and rivers of the Sundarbans mangroves, the saltwater crocodile is critically endangered in Bangladesh. It inhabits brackish water of coastal areas and rivers along the coast, coastal mangrove swamp forests and visits freshwater rivers and grass swamps too.

CITATION:

Aziz, M. A., & Islam, M, A. (2018). Population Status and Spatial Distribution of Saltwater Crocodile, Crocodylus Porosus in the Sundarbans of Bangladesh. ScienceDirect, 24, e01206. doi:10.3329/bjz.v46i1.37624


This article was first published in Mongabay.com


 

Banner image: One of the four saltwater crocodiles in Bangladesh with a newly installed satellite transmitter, released into the wild. Image by Md Mofizur Rahaman Chowdury.

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