Purse seine nets for overfishing could be killing marine mammals in Maharashtra: Experts
Excessive fishing along the Mumbai shoreline and several parts of the Konkan coast could be one of the reasons for the death of over 30 marine mammals — including whales, dolphins and porpoises — over the past two years, said marine expertsmumbai Updated: Jan 16, 2017 15:08 IST
Excessive fishing along the Mumbai shoreline and several parts of the Konkan coast could be one of the reasons for the death of over 30 marine mammals — including whales, dolphins and porpoises — over the past two years, said marine experts.
In just 15 days into the new year, the decomposed carcasses of two marine mammals – an Indo-Pacific humpbacked dolphin and a finless porpoise – washed ashore at Nariman Point, south Mumbai. HT spoke to government officials and marine biologists to find out what could be the reasons for such deaths.
Whales, dolphins and porpoises are endangered species and are protected under Schedule I of the Wildlife Protection Act, 1972.
Scientists agreed that the rate at which carcasses have been washing ashore was unusual in its frequency, especially over the past two years. “It is a cause of concern, as one of the primary reasons is pollution and poor water quality closer to the shore of big cities like Mumbai. Whales are the most affected by this issue,” said Vinay Deshmukh, marine biologist and former chief scientist, Central Marine Fisheries Research Institute (CMFRI). “The other reason could be excessive fishing and the use of the Purse seine nets — large fishing nets used to catch fish in bulk — for the death of dolphins and porpoises.”
Purse seine nets were banned by the state across 12 nautical miles from the coast of Maharashtra from January 1, in a bid to safeguard different species of fish and increase their population.
Purse seine nets can stretch from 500m to 1km, and sometimes fishermen attach two or three such nets and cover an area of 3km, pulling out a large proportion of fish population. The nets have a mesh that spans 25 mm to 35mm. This blocks small fish and fish eggs from falling back into the ocean, thereby stopping them from multiplying.
“While catching a lot of fish at one go, larger mammals like dolphins and porpoises are entangled within these nets in their search for small fish, which makes for a major portion of their food. This happens because of the sheer expanse of the nets,” said Deshmukh. “They need air to breathe, and so these mammals come closer to the surface intermittently. When they get caught in the nets, they suffocate and sometimes drown. Overtime, they wash ashore with the flow of the tide.”
In February last year, the state government had restricted the use of such nets for sustainable fishing practices. The guidelines brought down permits from 494 to 182, and allowed the use of such nets only between September and December, in certain areas along the 720km coastline of Mahrashtra.
State government officials said that there was an immediate need to change fishing gear and practices or incidents of mammal deaths will continue. “It is a fact that there is over-exploitation when it comes to fishing, much more than our coasts can bear. We are trying to make fishermen aware of the need to shift to a more conservation-oriented practice. In Sindhudurg, fishermen have moved to square mesh nets for this very reason,” said N Vasudevan, chief conservator of forest, state mangrove cell. “Along with the fisheries department, the state forest department will patrol the Maharashtra coast to check such incidents.”
Officials from the fisheries department said that a team had been formed to investigate the deaths. “As far as the Purse seine fishing net issue is concerned, we have banned them but our jurisdiction is as far as 12 nautical miles from the coast of Maharashtra. Beyond that, it is the Central government’s prerogative,” said MB Gaikwad, commissioner, state fisheries department. “However, when it comes to such cases of overfishing, we will be taking action against violators and a report will be drafted to ascertain the exact reasons behind the mammal deaths.”
State fisheries can now take action under Wildlife Protection Act, 1972
In a move that might boost marine conservation, the state government has given the state fisheries department the authority to book persons involved in violating the Wildlife Protection Act (WPA), 1972, by endangering the lives of marine mammals protected under it.
“The state fisheries, along with the forest department, can now take action against instances of cruelty against whales, dolphins, porpoises, turtles and tortoises, all protected under Schedule I of WPA. The government passed the order last year and it comes into effect from this year onwards,” said a senior official from the state environment department.
Major cases of mammal deaths (2015-17)
· January 15, 2017: The carcass of a three-foot finless porpoise washed ashore, opposite Taj Hotel, Nariman Point in south Mumbai
· January 1, 2017: A five-foot dolphin carcass had washed ashore at Nariman Point. Mangrove cell officials said that the exact cause of death was not known but the dolphin had several marks on its head, almost as if it had lost direction and hit a hard surface of a ship or rock several times.
October 7, 2016: A mutilated carcass of a 35-foot Blue Whale, the largest mammal in the world, washed ashore at Guhaghar beach.
September 11, 2016 : A 47-foot Blue Whale, the largest mammal in the world, was rescued from a beach near Madban village, close to Jaitapur Nuclear Power Plant in Ratnagiri district. It was rescued by forest officials with two boats and 50 people.
February, 2016: A 40-foot Blue Whale was rescued with the help of two boats in a nine-hour rescue operation near Daboli, Ratnagiri. This was the first ever successful rescue operation carried out along the coast of Maharashtra for the largest mammal in the world. A 20-member team had used two boats to rescue it.
January, 2016: The carcass of a 40-foot male Bryde’s whale washed up at Juhu beach, near Juhu Tara Road, on January 29. The whale was beached for 17 hours and could not be rescued and sent back to the sea. The carcass of the whale was burnt and buried at Juhu beach after the rescue operation failed.
· March 2, 2016: Three cases of dolphin carcasses that washed ashore at Girgaum Chowpatty, Gorai beach and Bhuigaon beach, Vasai
· December 13, 2015: The carcass of a two-and-a-half-foot finless porpoise, protected under the Wildlife Protection Act, washed ashore near Haji Ali Dargah
· November 27, 2015: The carcass of a six-and-a-half-foot Indo-Pacific humpback dolphin washed ashore near Bhagwanlal Indrajit Road, Malabar Hill
· July 22, 2015: A six-foot carcass of an Indo-Pacific humpback dolphin with injuries on its body was discovered on Bhuigaon beach in Vasai. The high tide carried it back into the sea, said local fishermen
· June 17, 2015: The carcass of a seven-foot dolphin was found on Vasai beach
· June 1, 2015: The mutilated carcass of a humpback whale was found on Manori beach. Only the skin and skeleton of the whale could be recovered as all the other body parts had decomposed; it could not been sent for a post-mortem
· May 5, 2015: Carcass of a six-foot Indo-Pacific dolphin was found at Versova beach. A four-foot dead porpoise was also found at the same location. A post-mortem was conducted in both cases and the bodies were burnt at an isolated location in Andheri
· April 27, 2015: A six-foot dead dolphin was found wedged in the rocks near Oberoi Hotel at Nariman Point. The carcass had decomposd in such a manner that a post-mortem could not confirm the cause of death.