Ahmedabad
CIFRI Discovery: They came into the estuary with high tide
Updated : Jan 12, 2019, 06:10 AM IST
In what is believed to be the first such instance to be reported, around 17 Octopuses were found in the Narmada River. It should be noted that until date, there are no known records of Octopuses being found in the river.
The Octopuses, ranging in length from 190-320mm, were found during a routine survey by a research team of Indian Council of Agricultural Research (ICARC), Central Inland Fisheries Research Institute (CIFRI), Vadodara. An update put up on the ICAR website said that Cistopus indicus, commonly known as old woman Octopus, was observed for the first time at the estuarine zone of the Narmada at Bhadbhut region, which is 35km from the sea.
It should be noted that Octopuses are marine creatures and aren't known to survive in fresh water.
An official in the know said that the Octopuses may have landed in the estuary during high tide. "The water here is brackish and at the time of the catch, the salinity level was quite high. So that is how it would have survived," said the official.
A marine science professor who did not wish to be quoted said that presence of Octopus in Narmada River has so far been unheard of. "They are essentially marine species and can't survive in sweetwater conditions. But since this was an estuary, in all probability, they came in with the tide and when the sea water comes in during the tide, the salinity level is quite high and so the Octopuses could survive in it. If not caught, they would have found their way to the sea during the next tide," said the professor.
As per the ICAR website, the maximum length of the species reported so far has been 600mm, from the Bay of Bengal. Apart from the Octopuses, the other marine species that were caught during the survey included several species of fishes including juvenile Hilsa fish.
The ICAR said that salinity of Bhadbhut and the adjacent Mahegam region was in the range of 18-20 ppt during December 2018 and the high salinity, along with the flow of flood tide may be the reason for the ingress of true marine species such as Octopus into the estuary.
Source: ICAR-CIFRI