Conservationists have criticised an event during a seafood festival in which a shark was paraded through a British port city before being chopped up, cooked and served to onlookers.

The blue shark, a near-threatened species, was hoisted in the air by two men and carried through Plymouth, Devon, before being deposited on a stage where it formed part of a cookery demonstration.

Experts from the Ocean Conservation Trust, which is based in Plymouth, led criticism of the scenes on the historic waterside area, the Barbican. Helen Gowans from the charity said: “As an ocean conservation charity, we do not condone the eating of blue shark and were disappointed to see that a blue shark was shown off as well as being featured on the chef’s stage.”

It is understood the shark was landed as “by-catch”, when fish and other marine creatures are trapped by commercial fishing nets by mistake. Members of the public reacted with outrage on Facebook.

One woman said: “In a time and city where we are encouraged to help with the protection and conservation of sharks many people think this is just terrible, especially with shark numbers dwindling.”

Another person wrote: “Totally out of order, killed and paraded. I thought these days were over.”

Plymouth city council said: “Unfortunately during this year’s Seafood festival a shark was inadvertently caught as a by-catch by a local fisherman on one of their regular commercial fishing activities and was then brought to the ‘catch of the day’ session on the main stage of the Seafood festival.

“We and our partners are committed to protecting our marine environment and sustainable fishing, especially around endangered species such as sharks, and we do not condone what happened and we want to make sure this does not happen again in future events.”

Globally, the blue shark is listed as near threatened on the International Union for Conservation of Nature red list. In the UK, it is a priority species under the UK post-2010 biodiversity framework.

A spokesperson for the Shark Trust said: “Sharks are an inevitable part of by-catch, and at this time blue shark can be legally retained, sold and consumed. Having seen the photographs related to the auction, and how the shark was handled, we can appreciate that this caused distress to some festivalgoers, and was not the most appropriate approach.”