Two more Hector's dolphins found dead, as advocates fear 'tip of the iceberg' scenario

Saturday, 20 August 2022

Hector’s dolphins, and their critically endangered subspecies the Māui dolphin, are only found in New Zealand’s waters (File photo).

Warning: Article shows graphic photos of dead Hector’s dolphins.

Two more threatened Hector’s dolphins have been found dead on South Island beaches right on the tail of 15 others in recent months, leaving conservationists fearing a “tip of the iceberg” scenario.

The Department of Conservation's (DOC) Hector’s and Māui dolphin incident database shows the dolphins were discovered on Farewell Spit on August 6, and on the West Coast’s Gillespies Beach on August 12.

In the year to July 31, 19 other Hector’s and Māui dolphins have been found dead and reported to DOC. It marked a six-fold increase on the year before – from August 2020 to July 2021 – when just three deaths were reported, although Covid-19 might have had an impact on reporting.

* Body of dead Māui dolphin wasn't picked up because email went to off-duty ranger

* Four Hector's dolphins, including three calves, found dead on South Island beaches

A hector's dolphin has had a lucky escape after being entangled in a cray pot buoy line in Akaroa’s Marine Reserve near Haylocks Bay.

Hector’s dolphin advocate Genevieve Robinson said she was angry and frustrated when she first learned of the deaths this week.

While their causes of death were not immediately obvious, the one found on Farewell Spit was a “lovely, chunky, shiny dolphin”, which appeared to have been in good shape.

There were a number of serious issues impacting the marine mammals, including warming seas, food availability, diseases like toxoplasmosis, and ending up as accidental bycatch in commercial fishing operations.

Hector’s dolphin advocate Genevieve Robinson is standing for Environment Canterbury (file photo).

While there was some positive conservation and protection work happening for land-dwelling species, Aotearoa’s native ocean-dwellers were sometimes “out of sight, out of mind”, she said.

Hector’s dolphins live in small, isolated populations with relatively small ranges and reproduce slowly, and she feared the loss of so many individuals could be a problem.

Robinson, who is running for Environment Canterbury in the coming election, said regional councils had jurisdiction up to 12 nautical miles – around 22km – from shore.

One of the at-risk Hector's dolphins found dead on South Island beaches this month.

The dolphins mostly stuck to coastal waters, so councils should be doing everything they could to protect them, she said, including having up-to-date coastal plans.

“Not only do regional councils have the ability [to take action], they have the duty.

“These animals are worth so much more in the water than they are on the shore.”

The first dead Hector’s dolphin was found on Farewell Spit.

Robinson had previously raised concerns about commercial fishing in dolphin habitat.

According to DOC’s database at least 13 Hector’s dolphins had died in commercial fishing nets near Canterbury’s Banks Peninsula alone since August 2017.

In one February 2018 incident five dolphins were killed, and twice – in December 2018 and February 2019 – three dolphins were caught.

“I think we need to hold fisheries to account… and government as a whole, because we are failing our endemic species.”

DOC aquatic director Kirstie Knowles said the latest dead dolphin, a juvenile male, was discovered by a staff member at Gillespies Beach, near Fox Glacier.

“Staff from the Fox Glacier Field Centre are assessing suitability of sending the somewhat decomposed carcass to Massey University for further examination.”

The dead female Hector’s dolphin found earlier at Farewell Spit, and a cluster of 15 beachcast Hector’s dolphins found around the South Island between November 2021 and May 2022 were not a huge cause for concern, she said.

“This number of dead Hector’s dolphins is not entirely unexpected and isn’t likely to have an impact on the population.”

But Professor Liz Slooten, of the NZ Whale and Dolphin Trust, found the numbers hugely concerning.

“The number [of dead dolphins] that actually end up on a beach, then are actually found by people, then are reported… this is the tip of the iceberg.”

“But even that tip of the iceberg is getting larger rather than smaller.”

The fact there had not been a decline in numbers suggested dolphin protection measures enacted in 2020 might not be paying off, she said.

One of the smallest marine mammals in the world, Hector’s dolphins are only found in New Zealand’s waters and are considered nationally vulnerable, with a population of about 15,000.

Their North Island subspecies, the Māui dolphin, is critically endangered, with as few as 54 individuals left.