A native longfin eel nicknamed ‘Tina Tuna’ has had life-saving surgery at Wellington Zoo, after being spotted with a large head wound while swimming in Kaiwharawhara Stream at Ōtari-Wilton’s Bush in Wellington.

 Tim Park, Ōtari-Wilton’s Bush Manager, caught Tina and popped her in an old tramping pack for a trip across Wellington to the zoo’s hospital for native wildlife, The Nest Te Kōhanga. 

It was the first time veterinarians at Te Kōhanga had operated on an eel, which presented a few challenges, as one of the vets Fiona Esam explained. 

"We’re mostly used to dealing with mammals and birds up there, but fish have a completely different kind of vascular system. They respond really differently to anaesthesia, we can’t intubate an eel, we can’t give them anaesthetic gases," he said.

The team called upon the expert knowledge of the zoo’s Reptile Keepers, and took a DIY approach, creating a shallow pool for the procedure from a bin bag propped up with towels. The water bath contained anaesthetic, which was flushed over the gills of the slippery patient, keeping her sedated. 

Tina’s wound was successfully stitched up. Following a course of antibiotics and a few days of post-operative recovery under the care of Te Kōhanga, Tina hitched another ride in Park’s tramping pack, and was released back into Kaiwharawhara Stream today. 

Mana whenua were present to welcome her home. Lee Rauhina-August called a karanga maioha to Tina as she was released, to protect and calm the eel.  

‘It’s important to acknowledge our taonga and her return to the wai. As kaitiaki, Taranaki Whānui want to ensure that we can put a cloak of protection over her, and hopefully look after her in her natural environment," Rauhina-August said. 

Park suspects that an illegal attempt to catch Tina caused her injury. Longfin eels are protected in all Wellington City Council reserves and are a threatened species nationwide. 

One of the big threats for Wellington’s eels is loss of habitat. The majority of the city’s streams have been piped, and those that are left are under stress from pollution from stormwater runoff. Eels are the apex predator of the stream ecosystem, and so are particularly vulnerable to pollutants in the catchment.  

"Because we often get a lot of dog poo washed into the streams, we do sometimes have elevated levels of E. coli in the streams, and you see that in the condition of the eels here," Park said.  

Around 20 eels are seen regularly in Ōtari-Wilton’s Bush’s waterways, but Park estimates there could be up to 200 living in the reserve. Tina Tuna is one of the biggest.  

"She’s about five and a half kilos, so quite a chunky girl for an eel! I think at that weight she might be around 50 or 60 years old.’"

Esam said that Tina’s prognosis is excellent. 

"She’s lucky she’s a real regular here - they know exactly where she lives, so the staff here can keep an eye on her. There’s no reason she shouldn’t live on for many many more years."

Longfin eels can live to around 80 years old and have a unique life cycle, migrating to the Pacific Ocean at the end of their lives to breed.