Bangladesh imposed a ban on catching crabs to ensure its breeding at a wrong time over the years which ultimately failed to improve production of the high demand export item, said a recent study.
Khulna University teachers while unveiling the report on November 12 suggested the government to review the ban period of wild crab collection and called for extending support to farmers during the ban period through social safety network schemes.
For decades, Bangladesh considers January and February as breeding period of mud crabs based on perception but the researchers found the actual breeding period of wild mud crabs was March and April when mother crabs release eggs and the fecundity rate of a mud crab is 20 to 30 lakh.
Muhammad Yusuf Ali and Md Golam Sarower, professors of fisheries and marine resource technology discipline at Khulna University, conducted the study on lifecycle of mud crab.
They said to identify peak breeding season of the mud crab (Scylla olivacea), live crabs were collected monthly at every full moon during one high tide, about five to six hours, from May 2018 to April 2019 from the rivers adjacent to the Sunderbans in Shyamnagar of Satkhira.
Detailed biological analysis was carried out at the biology and histology laboratory of discipline at Khulna University.
They called for developing hatchery for artificial production of zoeas and said the hatchery-produced crablets were as good as the wild crablets.
The research was funded by the SDC-Shomosthi project implemented by Care Bangladesh.
Forest Department director Md Jahidul Kabir told New Age there was no previous study on crabs, so they set the time on perception. ‘If we find the study authentic, we will adapt and review the time,’ he said.
Mud crabs emerged as a potential item in Bangladesh’s export and became second largest agro-based item. Its farming increases rapidly in southern Bangladesh because of lucrative price and high demand in the international market.
Muhammad Yusuf Ali told New Age the farming or fattening of mud crab was entirely dependent on the capture of wild crablets as there was no hatchery to produce zoeas of crab in Bangladesh.
‘The rivers surrounding the Sunderbans are the only source of crab seeds in Bangladesh where production decreasing alarmingly every year,’ he said.
Bangladesh Fisheries Research Institute officials said crab production was getting popular in the southern costal districts including Satkhira, Khulna, Bagerhat after the shrimp industry faced critical time but collecting crab seed became a challenge.
Muhammad Abdur Rouf, chairman of fisheries and marine resource technology discipline at Khulna University, said the survey was conducted at a specific area and it needed a holistic study across the crab cultivating areas before taking policy decision.
Bangladesh Fisheries Research Institute principal scientific officer Md Latiful Islam said it required a complete study before taking decision on reviewing ban period as crabs’ breeding sometimes depends on rain and weather.
He said for high price and low-disease risks, crab farming replaced shrimp farming as it became risky for different diseases. Four to five lakhs people are now involved with farming and trading of crabs.
So far 13 varieties of crabs are found in Bangladesh but only mud crab is exported as presence of other crabs is very low.
Bangladesh Fisheries Research Institute officials suggested to protect mother crabs during breeding like Hilsha and called for hatchery production to save the ecosystem of the marine belt.
Crab exporters said on an average Bangladesh exports 11,000 tonnes of crab to countries including Malaysia, Singapore, China, Japan, Hong Kong and Korea.
Export Promotion Bureau of Bangladesh statistics shows Bangladesh exported crabs worth $ 42.93 million in 2018-19 fiscal years only. It was $23.82 million in 2015-16 and $7.2 million in 2010-11.
Cab meat is low in fat, high in protein, and a moderate source of omega-3 fatty acids.
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