Mumbai, Jan 6:
In a first along the Indian coastline, an octopus species about the size of a human arm was recently spotted in the estuarine zone of Narmada river, said scientists. Marine biologists confirmed that there were no previous reports of octopuses being spotted in inland waters along the Indian coastline.
Octopus is a marine species that is spotted up to the depth of 50m and is known to inhabit coastal sea waters. It is rarely observed in the estuarine brackish waters.
Seventeen specimens of the Cistopus indicus, commonly known as the old woman octopus, were identified by scientists from the Central Inland Fisheries Research Institute (CIFRI) Vadodra, Gujarat, under the Indian Council of Agricultural Research (ICAR). The octopuses were spotted during CIFRI’s routine survey as a part of a fish catch at Bhadbhut village, 35kms off the Gulf of Khambhat on December 16. CIFRI scientists declared their findings on Friday. “According to data collated by us since 1988, in India, octopuses are caught mainly as by-catch in trawl nets used for shrimp trawling, shore seines, boat seines, hooks, lines and stake nets, but they have never been caught within brackish estuarine water bodies,” said Dr Dibakar Bhakta, scientist, CIFRI Vadodra.
The 17 specimens are 190-320mm in length. The maximum length of the species was 325mm with a weight of 56.2g. The maximum length of this species along the Indian coastline was 600mm from the Bay of Bengal, said Bhatka. There are around 200 species of Octopus reported across the world and 38 species reported from Indian seas.
“Initial analysis and high salinity show that ingress of high tide water may have allowed this marine species into the estuary. However, considering the low quantity of marine fish catch in these brackish waters between 2017 and 2018, environmental disturbances and anthropogenic alterations to their habitat can be another cause for their displacement,” said Bhakta.
Deepak Apte, director, Bombay Natural History Society, said marine species, mostly fish, are known to move into brackish waters for breeding mostly around winter months. “However, there are no previous records of octopuses depicting such behaviour.”