On March 29, a humpback baleen whale was found dead on the Uran coast. The whale’s carcass was washed ashore with deep cuts on it. Without conducting a preliminary post mortem, the whale’s carcass was disposed of. Locals and forest officials, too, found nothing unusual.
Over the next two months, the city saw 11 similar incidents where marine mammals such as whales, dolphins and sea turtles were washed ashore, dead. Apart from these 11 instances, five instances were also reported from the Ratnagiri coast in southern Maharashtra. In at least seven of these cases, the mammals were covered with oil and had deep cuts on their carcasses.
In another mysterious incident in Velas, Ratnagiri, in the first week of April, two pet dogs of a local, Mohan Upadhyay, died after licking the carcass of a whale.
The unusual frequency of these deaths has perplexed marine ecologists and environmentalists alike. Several environmentalists have also claimed that the mammals may have fallen prey to the toxic oil pollution in the Arabian Sea or may have been hit by the propellers of a ship.
These events have put the debate on marine pollution and marine ecology conservation back in the spotlight. “The death of these marine creatures, which is unnatural, points to environmental degradation of marine life. Of the 20 whale species found in the Arabian Sea, certain species migrate in search of plankton. If the content of heavy metals in the aquatic vegetation has increased, it may have harmed these mammals,” said Dr Vinay Deshmukh, scientist in charge, Central Marine Fisheries Research Institute (CMFRI).
“Marine pollution affects all aquatic life. The amount of industrial and domestic waste released from the city into the west coast is considerable, and its effect needs to be investigated,” said Deshmukh, who has been asked by the forest department to conduct a thorough study on the deaths of marine mammals.
As per current data, Mumbai generates 3,000 million litres of sewage a day (mld). This sewage, which is only partially treated, is released into the west coast via creeks using the drainage outfalls at Bhandup, Ghatkopar, Thane, Colaba, Versova and Malad, Bandra and Dharavi.
According to P Sakhare, chief engineer, sewerage operations, BMC this waste is fully treated at six sewage treatment plants located at Colaba, Worli, Bandra, Ghatkopar, Bhandup and Versova. “The treated sewage is released into the west coast from three marine outfalls at Colaba, Worli and Bandra, while at Bhandup and Ghatkopar we have aerated lagoons, where waste water is treated in a pond through artificial aeration,” Sakhare said.
Environmentalists claim the effluents released in the creeks and sea and oil pollution are entering our food chain and also turning water bodies into nullahs. “Marine vegetation feeds on the effluents which in turn is consumed by the fish. Most fish in creeks and wetlands is sold in markets and so pollution enters our food chain,” said Stalin D, director (projects), Vanashakti non-profit organisation.
Plastic debris is another major source of marine pollution. “The use of plastic on the coast should be restricted as it often ends up harming marine ecology,” said N Vasudevan, chief conservator of forests (mangroves).
According to Dr Shankar Gajbhiye, chief scientist, National Institute of Oceanography (NIO), although the level of heavy metals in the west coast has decreased, the effluents released in the creeks and beaches has had an adverse localised impact, polluting them immensely.
“Versova and Mahim beaches are hotspots of organic pollution. Marve creek is also highly polluted,” Gajbhiye said.