The giant marine mammal, which has died, was swept to shore on Friday.
Essex Police said it is working with other organisations to plan how to remove it.
Officers have urged people to stay away from area in a bid to ensure social distancing guidelines aimed at curtailing the coronavirus pandemic are adhered to.
"The area is cordoned off and the public are advised to stay away," the force said in a statement posted on its Facebook page.
Eyewitnesses meanwhile described the carcass as a "very sad sight".
Dave Bolton, 83, told the BBC: "I was driving along the seafront when I saw lots of people looking over the railings, so I got out and saw the poor animal - it was a very sad sight indeed."
There have been frequent reports of large marine animals washing up on Britain's beaches in recent years.
A total of 4,896 whales, dolphins and porpoises died on beaches between 2011 and 2017, according to a report published last year.
The tally marked a 15 per cent increase on the corresponding figure for the previous seven years.
Led by Rob Deaville of the Zoological Society of London, scientists compiling the report found a number of causes for the deaths, including infectious diseases, fishing and plastic consumption.