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Rs 100 crore crab industry under threat from biodiversity loss, indiscriminate crabbing

Rs 100 crore crab industry under threat from biodiversity loss, indiscriminate crabbing

With no legal control and monitoring mechanism, over exploitation of mud crabs from the wild has resulted in the stagnation of fisheries production of this species across the country, affecting the livelihood of many in the coastal districts.


Sumitra Samanth in her shop

Karwar, March 7 (G’nY news service): Sumitra Samanth, a 58 year old fisherwoman engaged in the trade of mud crabs for the past four decades, is a worried lady today with the declining population of commercially important crab varieties. Though it affects her income earning capacity, Samanth, who hails from the coastal town of Karwar, Karnataka on the west coast of India, is unaware of the reason behind the decline in production.

According to marine biologists, an estimated 20,000-25,000 families across the country are dependent on mud crabbing. There are around 4,000 families dependent on mud crabbing in Karwar and surrounding districts of Karnataka alone, whose livelihood is under threat.
“A decade ago, I used to get 10 kg of green crabs in a day. Now I get only around 3 kg a day. The fishermen who sell the crabs to me hardly earn Rs 200 per day. The increasing costs make it very difficult for us to manage with such low income,” Samanth said.

The mud crabs, dark green to dark brown in colour, are all picked up within the first two hours of the start of business from the small shop in the Karwar fish market. The crabs, that were earlier affordable and consumed regularly by people from all walks of life, are priced at nearly Rs 800 per kilogram today, making them unaffordable for many. In the international market these crabs fetch around Rs 1,600- 1,800 for a kilogram.

“The poor cannot afford to eat the crabs that I sell. Most of my stock is picked up by the hoteliers or exporters. There is demand for the product, but we do not have enough supply,” Samanth said. The mud crab is a delicacy in high demand in South-East Asian countries like Singapore, Malaysia, Taiwan and Bangkok. The prices have shot up by 250- 300 per cent in the last three years.

Mud crabs are found in shallow coastal water, brackish-water lakes, estuaries, intertidal swamps and mangrove areas, and are often sold live. According to the Marine Products Export Development Authority (MPEDA) figures, India earns foreign exchange to the tune of 18 million USD by way of exports. Thus, the natural stock of mud crabs is under constant pressure from fishing in the country.


Mud crabs

Mangrove ecosystems have ecological and economic significance in coastal protection, enrichment of water quality and also in production of fishery resources. According to the Forest Department data, mangroves are spread across 900-1000 hectares in Karnataka. Crabs depend directly on mangrove areas for survival, by feeding on leaves and litter. There are about 15 crab species identified in the Karwar mangrove environment along the Kali river estuary. While marine experts attribute the decline to various reasons like increasing water pollution, indiscriminate use of pesticide in the agricultural fields adjoining the river, sprawling aquaculture and exploitation of mangrove forest, the indiscriminate fishing of berried female crabs seem to be the prominent cause.

Though there is no definitive study to show the decline in production, a research report by Pradnya D Bandekar, Department of Marine Biology, Karnataka University, Karwar, 2007-2011, ‘Biodiversity of Crabs in Karwar Mangrove Enviroment, West Coast of India’ , the population of commercially important mangrove crabs i.e Scylla serrata and Scylla tranquebarica, are declining day by day due to indiscriminate fishing of berried (egg-carrying) females, and also fishing of undersized crabs.

Bandekar says that in recent years, mangrove areas have been converted to shrimp ponds and the discharged effluents from the shrimp farms are also causing a threat to the crab population. She points out that the increase in pollution around mangrove ecosystem by man-made chemicals due to aquaculture practices is also adding pressure on crab population and hence conservation of mangrove crabs is important.

A single female crab can produce up to eight million eggs in one mating season, which extends from October to December. The study indicates that most of the juveniles and females of smaller crabs were distributed along the lower shore regions. Bandekar opines that crabbing should be strictly banned during their peak breeding season, and awareness should be created among the fishing community about the depletion of the crabs.

Samanth disagrees with Bandekar and claims that the berried crabs are released, if at all they are caught in the nest, and are not sold in the market. But experts deny this and report that such trade is rampant as it fetches a good market value in countries like Singapore.

Fisherfolk leader Ganapathy Mangre in Karwar said it was not right to place the blame squarely on the fishing community and noted that industrial pollution should also be taken into account. “The water discharged from the industries into the river could also be a reason for the decline of crab catch. There should be some study to find the cause and effect,” Mangre adds.

Crab nesting site

Crab nesting site along the mangrove forest located on Kali river

Meanwhile, Dr V N Nayak, a marine biologist in Karwar says that the phenomenon is not restricted to the region of Karwar alone, but is spread all across the country including the Sunderban in West Bengal. “Today, most of the mangroves spread in and around Karwar is on private land. So, we do not have any control. Cutting a mangrove species should be treated as a crime on par with cutting a sandalwood tree. Rules should be framed to protect the mangroves and the crab species,” Naik said.

According to a report by West Bengal University of Animal and Fishery Sciences, Kolkata, 2012, ‘Climate Change Vulnerabilities, Aquaculture Practices & Coping Measures in Sagar and Basanti Blocks of Indian Sundarban’, not only were the crab varieties reported to have declined, but also drastic reduction was reported in some native fish species over the last thirty years.

Dr. B. Meenakumari, Deputy Director General (Fisheries), Indian Council of Agriculture Research said, unlike for lobsters, there is no law governing the catch of female berried crabs and given the vast ecosystem it was highly impossible to place controls. “Of late, we are sensitizing fishing communities about the issue, and are creating awareness programs wherever possible through various research and training institutes,” she said. “Besides, mud crab aquaculture is also promoted in order to strengthen the production base and facilitate a sustainable source of mud crabs for exports.”

The Rajiv Gandhi Centre for Aquaculture (RGCA), the R&D arm of MPEDA, Tamil Nadu, works on production of mud crab seeds in the hatchery. Crab fattening is also being practiced in parts of coastal areas, wherein crabs caught from the wild are reared in brackish water ponds in estuaries until they are hard and ready for marketing.

Contributed by Prabhu Mallikarjunan
Photo credits: Prabhu M

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