Thursday, December 7, 2023

DNA barcoding to the rescue of India’s ornamental fish

By Sahana Ghosh
Kolkata, April 20 (IANS)
Indian scientists are using a new approach to identify animal species based on genetic labels or barcodes, that can help monitor and clamp down on trafficking of ornamental fish from northeast India – a biodiversity hotspot – and aid conservation.

Just as shopkeepers scan the similar-yet-different zebra stripes (barcodes) on products to keep track of what they sell and what is in stock, examining certain ubiquitous genetic sequences can differentiate one species from the other with high accuracy.

The upshot, says biotechnologist Sankar Kumar Ghosh, is that DNA barcoding can be applied even when traditional methods fail.

“Combined with traditional methods of identification, barcoding can pinpoint threatened fish species being sold under nicknames or popular trade names by exporters in northeast India, to mislead and avoid detection,” Ghosh, professor, department of biotechnology at Assam University, Silchar, told IANS.

To lure hobbyists and enthusiasts, dealers in the northeastern states also adopt other unfair practices like use of synthetic dyes to impart colours to fishes to make them attractive.

The northeastern region is home to around 267 species of fish and about 250 are known for their ornamental value – colourful, bizarre shapes with patterns that look good in an aquarium display or recreational ponds, said Ghosh.

According to a Central Inland Fisheries Research Institute report, the region is the contributor to 80 percent of Indian ornamental fish trade.

From small varieties like snakeheads (murrells) to bigger catfish and other unusual looking species, most fetch a good price in the domestic as well as international markets in neighbouring countries like Nepal and Singapore, said Ghosh.

“Although there exists several regulatory enactments in India, aquarium fish are traded largely without endowment to the government and mostly from wild capture. This poses a threat of endangering the species,” he said.

This has necessitated cataloguing the ornamental fish reserve and its diversity in the region.

“So we collected over 100 samples of ornamental fish from river beds (the Brahmaputra, the Barak in Assam and rivers from Manipur and Tripura) and traders in northeastern states and used DNA barcoding to correctly identify 51 ornamental fish species which are exported from northeast India.

“Of these, around 30 percent were found to belong to the threatened category. Our study has established that the technique can monitor and regulate trafficking of fish species and help conserve wildlife,” Ghosh said. Of the identified species, as many as 14 are sold under multiple trade names, the study said.

Carried out by research scholar Bishal Dhar under Ghosh’s supervision, the study was published in the Gene journal in February this year.

Apart from creation of a DNA barcode library (or catalogue), the aim of the research is to generate awareness on bringing in new regulations that would resist the use of trade names while exporting a biological resource, said Ghosh.

“We also recommend the use of proper zoological names of the species along with DNA barcode tag as an identifier while exporting,” he said.

The global annual turnover of ornamental fish trade is estimated at about $10 billion with a growth rate of six percent per annum.

Although India’s contribution to the global ornamental fish trade is meagre at present, the country has a great potential to increase the present level of export to about Rs.150 crore annually, said S.P. Biswas, a specialist in fish biology and ecology, citing a recent report.

“It is a very serious issue in the northeastern states. Ornamental fish have a very high demand in the international market and habitat destruction is also a major issue. Genetic methods should be quick enough to identify the species.

“Priority should be given to updating the list of ornamental fish fauna of the region. Also, modern techniques should be adopted for identification of fish species in order to get rid of taxonomic discrepancies,” Biswas, professor, Department of Life Sciences, Dibrugarh University, Assam, told IANS.

(Sahana Ghosh can be contacted at [email protected] )

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