A sperm whale spotted near the mouth of the Yodo River in Osaka last week, that was subsequently confirmed dead, will be sunk off Osaka Bay, the city mayor said Tuesday.

Ichiro Matsui told reporters that he hopes the disposal, which entails removing built-up gas from the animal's carcass to prevent an explosion before moving it by ship, will be completed within the week.

There was talk of temporarily burying its body on land to reduce it to a skeletal specimen for a museum, but the mayor said there had been no requests.

"The whale came from the ocean, so we want to return it there after its death," he added.

The estimated 15-meter whale — nicknamed "Yodo-chan" on social media — was first sighted on the morning of Jan. 9 after straying into the mouth of the river. It became progressively weaker and was confirmed dead Friday by experts, according to the city.

The bay is largely enclosed by Awaji Island, which leaves two narrow passages north and south. The southern opening leads to the Pacific.