Huge Bluefin Tuna, The Weight Of A Motorbike, Stranded In Chichester Harbour

A large Atlantic bluefin tuna fish, weighing nearly 180kg and about 2 metres long, has been discovered on the shore of Chichester Harbour.

Chichester Harbour Conservancy Staff said they located and recovered the fish on Wednesday (September 2) following a report of a "large, stranded dead fish" at Thorney Island Yacht Club.

But they needed the help of the Sussex Inshore Fisheries and Conservation Authority to recover the animal properly.

The large tuna, described by conservationists as "scarce", was transferred to the deck of fisheries' patrol vessel "Watchful" with a davit and winch, where upon it was identified as the tuna species Atlantic Bluefin.

The authority said it was then transported to Shoreham-by-Sea where the fish was landed ashore and stored overnight at fisheries wholesaler and retailer Monteums Ltd.

IFCA Officers Dr. Jen Lewis and Nick Rogers later conducted sampling work on the carcass, collecting key measurements and tissue samples, including the removal of the fish otoliths (small bones that exhibit growth rings) from the head to provide essential information on the age and growth of the fish.

The fish showed no immediate signs of damage, or any evidence that it had encountered any fishing gear causing its death.

It was also evident the fish had only recently died given its condition and lack of damage or decomposition.

Given that the cause of death was unknown, the carcass was properly disposed of once all samples had been collected.

According to the Sussex IFCA, The IUCN (International Union for the Conservation of Nature) improved their Eastern Atlantic Bluefin tuna entry from “endangered” to “near threatened” in 2015.

It's reported that this positive change in designation reflects the improving state of the stock but underlines the continued need for a cautious approach to its management.

Currently the UK holds no quota for Bluefin tuna and no commercial UK fishing vessels are allowed to catch the species.

Any Bluefin tuna caught by any UK vessel must be returned to the sea, alive and unharmed.

At present recreational sea anglers are not permitted to target Bluefin tuna and must release any unintended catches unharmed.

Unusually for a fish, this species of tuna is warm blooded (homeothermic) and this enables the fish to successfully range over vast distances between warm and cool sea areas, as far north as Norway and Newfoundland and south to West Africa and Brazil.

Historically bluefin tuna regularly frequented UK waters, feeding upon plentiful prey fish species such as herring and mackerel.

However global fishing pressure due to high demand and prices caused bluefin numbers to drastically decline over the past century, to the point that they were classified as an endangered species by the IUCN.

Chief Fisheries & Conservation Officer, Tim Dapling explained:

"This is a very unusual and positive event in terms of fisheries the marine environment and the presence of a key species.

"Although it is a pity the fish was not alive, it is first time we have an encountered at close quarters a Bluefin tuna specimen in Sussex coastal waters.

"There are various reports of Bluefin tuna in the wider channel area and we know they are regularly sighted further to the west off Devon and Cornwall.

He continued:

"It was a quite remarkable and impressive fish, why it was in Chichester Harbour or came ashore may never be clear, but we do know species such as mackerel and bass are present in numbers within the harbour and perhaps it entered the harbour to feed and became disorientated.

"Presently we have spring tides, and at low water the channels of the harbour can be relatively shallow and narrow.

"A fish of this size and species is used to open sea areas where it can swim unconstrained to hunt prey.

"Working together with both colleagues in other organisations and the support of Monteums Ltd we were able to ensure benefit from the situation.

"The essential biological information collected will in a small way feed into strategic research on Bluefin tuna in the northeast Atlantic."