The latest death, in a fishery with just 13 per cent observer coverage, occurred in early June off the Canterbury coast in Pegasus Bay when a Hector’s dolphin, a species classed as “nationally vulnerable” with a high risk of extinction in the medium term, was accidentally caught by a commercial fishing trawler.
It follows another caught at the end of April off the Otago coastline, north of Taiaroa Head, in a set net from a commercial fishing vessel - the first death of the species recorded in the area for 10 years.
They are among five known deaths believed to be due to commercial fishing in the past year, and 15 others, the majority of which died of unknown causes. As four were female, they have raised concerns about the impacts on population recovery.
Hector’s dolphins are one of the world’s smallest marine mammals and are only found in New Zealand’s waters - mostly around the South Island - with a population of about 15,000. The North Island subspecies, the Māui dolphin, is critically endangered with an estimated 54 remaining.
The latest deaths come after the Government introduced fishing-related mortality limits for Hector’s dolphins at the end of last year for the first time, designed to help the species - once declining at an estimated rate of six per cent each year - recover.
The limits overall allow 46 Hector’s dolphins a year on the South Island’s east coast to end up as accidental fishing bycatch. David Parker, who was Oceans and Fisheries Minister at the time, said the rates were set at below half the species’ population sustainability thresholds.
A 2019 Ministry of Primary Industry paper estimated about 58 Hector’s dolphins were killed a year in commercial fishing bycatch, along with 334 due to toxoplasmosis, which is spread through cat faeces (although this figure has been heavily disputed - dolphin expert and University of Otago Professor Liz Slooten called it “nonsense”).
The current limits were based on specific population sizes based around the South Island, and different thresholds trigger different responses.
Off Banks Peninsula, the limit is 20 - meaning the latest death triggered only voluntary responses for the individual operator.
The Otago limit was two, meaning the single death saw Fisheries New Zealand step in to work with the industry and increase monitoring.
Only when more than three-quarters of a bycatch limit was reached could any enforcement action take place - such as area- or method-based fishery closures.
Green Party conservation spokeswoman Eugenie Sage said those plans were inadequate because they relied on voluntary measures and discussions with fishers when dolphins were killed. She was also concerned they didn’t apply on the West Coast, where most of the South Island population of Hector’s dolphins was found.
She added that the limits were also too high, and had not been based on the best science available.
Sage has proposed an amendment to the Marine Mammals Protection Act, which she says would better protect those species along with the New Zealand sea lion population and Māui dolphins.
The critically-endangered Māui dolphin population, based off the North Island’s west coast, has a mortality limit of one. The Minister of Oceans and Fisheries has the power to close fisheries if deemed necessary.
Sage’s Marine Mammals (Enhanced Protection) Member’s Bill, added to the ballot on Thursday, would make population management plans for threatened species, such as Hector’s dolphins and Māui dolphins, mandatory.
It would also introduce mandatory measures and require fisheries be closed to particular fishing methods if certain bycatch limits were reached - these would also be based on the best available science.
Sage said New Zealand was out of step with other countries such as the United States, which had a goal of zero bycatch and imposed strict rules if the number of marine mammal deaths started to affect the sustainability of a population.
She cited a US court decision that had seen New Zealand seafood exports to the US banned, signalling stronger regulatory protection was needed.
“Under the current law, development of a population management plan and a maximum allowable level of fishing-related mortality for species such as Māui and Hector’s dolphin is optional, as is the closure of a fishery. The bill makes that mandatory.”
Oceans and Fisheries Minister Rachel Brooking said she had been alerted to the latest deaths.
“Every dolphin death though is obviously not what we want to see.”
But Brooking said she was satisfied with how the current Hector’s dolphin protection measures had been implemented.
Other changes to protect these populations include a 2020 extension to commercial and recreational set-net fishing ban areas around Banks Peninsula will be further extended, and an extra 1100 square kilometres of South Island coastline will be closed to set-netting - protecting 17,600sq km in total.
Trawling closures and gear restrictions also covered more than 6900sq km of coastline.
These were alongside a nationwide ban on drift-netting, extensions to the marine mammal protection areas and a proposal to prohibit seismic surveying and seabed mining in the five marine mammal protection areas.
Brooking said there had been issues with observer coverage on boats due to poor watchkeeping practices on some vessels.
“Fisheries New Zealand is placing observers where it can, reporting any watchkeeping issues to Maritime New Zealand, and boosting other monitoring methods where appropriate.”
This meant in the year to June, just 13 per cent of bottom trawling events in the Canterbury region - where the latest Hector’s dolphin death occurred - were observed by Fisheries New Zealand observers.
Brooking said in the longer term, the rollout of onboard cameras - with the first tranche starting from August - would “significantly” increase the level of verification.
Initially, inshore trawling and set-net vessels fishing off the west coast of the North Island would be required to operate cameras.
Later this year, trawling and set-net vessels that fish off the north, east and south coasts of the South Island were expected to begin operating cameras.
By Michael Neilson
