SINGAPORE - The two most well-known otter families here have clashed again, more than a year after a fight that resulted in the death of at least one otter pup.

The Marina otter family clashed with its Bishan rival at the Kallang Basin on Wednesday (Oct 24), in an hour-long confrontation documented by otter watchers.

In a video uploaded on the Ottercity Facebook page, the two groups of otters are seen charging towards each other, baring their teeth and squeaking loudly.

But just as the two sides seemed set for a physical fight, the Marina otters retreated at the last minute. The Marina family was eventually split up and pursued by the Bishan family.

Subsequent footage showed the Bishan otters unsuccessfully pursuing two juvenile Marina otters on land.

Both sides eventually emerged from the clash without casualties, and the Marina family retreated to its home in Upper Peirce Reservoir.

Otter watcher Marjorie Chong, who documented the fight, said: "During the fight, there was no direct contact, although there was a lot of vocalisation and a lot of chasing.

"In a sense the fight was alarming, but not fatal - possibly because half the otters involved in the clash were still young and inexperienced."

She said the fight in the water lasted for about 10 minutes, and the Bishan otters pursued the Marina otters for another hour.

The two families fought in the Singapore River in July last year. The clash, which was won by the Bishan otters, caused the death of at least one Marina otter pup.

They eventually reached the mouth of the Kallang River by Tuesday, which was near the Bishan otters' current territory.

The clash then happened on Wednesday morning near the Merdeka Bridge.

Ms Chong said: "We held our breaths, as there was still a chance that they could make their way to the Singapore River without encountering the Bishan family.

"But it was fated, the two families came around the corner and bumped into each other."

Biology lecturer N. Sivasothi, who heads the OtterWatch group, told The Straits Times that physical contact in fights between otters is not usually the first action that the animals will take.

He said: "Physical contact happens when one family is much stronger than the other, there is very strong motivation to drive off another group, or when repeated encounters build up to extreme action.

"In the footage, the Marina otters break away without pursuing contact - they must have sized up the odds and broke off."

Otters are territorial carnivores like wolves, tigers and bears, which must maintain a territory large enough to support a prey population that they can feed on, said Mr Sivasothi.

"There are limits to the number of animals in any area, such as food and space. Weaker individuals are killed, or are driven away to poorer habitats which cannot support large families," he added.

"Attempts at intervention are ultimately futile, as environmental limits will force these clashes between wild animals."