Although no one's quite sure if by accident or design, there seems to be a definite 'purpose' to the arrival of an aquatic visitor to the River Bann.

Shoppers crossing Coleraine's Millennium footbridge in the town centre were this week stopped in their tracks when they noticed a harbour porpoise in the River Bann below them.

According to the Northern Ireland Environment Agency (NIEA), the mammal is apparently healthy, and swam upstream to take advantage of particularly high stocks of fish in the river.

"We observed the animal for over two hours, and it appeared to be feeding and stayed in the vicinity of the old Coleraine Bridge during this period," a spokesperson from the NIEA said.

"Its behaviour suggests that the animal was not in distress."

The body are continuing to monitor the health and wellbeing of the porpoise.

Porpoises are a relatively common species around the coasts of Northern Ireland with records of stranded whales, dolphins and porpoises, particularly along the North Antrim coast, on the increase.

According to the Irish Whale and Dolphin Group (IWDG), 2006 was the highest annual total of records was received since recordings began.

In fact, promoting awareness and recording of cetaceans in Northern Irish waters was on the agenda at an NIEA research and development conference earlier in 2008.

NIEA Coastal and Marine Communications Officer Gary Burrows, from Portrush, highlighted the importance of such recordings: "Encounters are viewed as exceptional events. With few records, conservation is restrained," he said, noting there is a range of animals found in Northern Ireland's seas, such as harbour porpoises, bottlenose dolphins, minke and killer whales.

NIEA research shows harbour porpoises are the most frequently sighted species in Northern Ireland and they are regularly sighted along the north coast.

Indeed, 29 porpoises were sighted along the coast in July alone and a school of at least eight dolphins was sighted one evening alone at Whiterocks, last month.

NIEA jointly funds a project with the IWDG - the Irish Scheme for Cetacean Observation and Public Education (ISCOPE) which aims to "promote better awareness and knowledge of cetaceans in Irish waters by encouraging public participation in recording."

(BMcC)