Yet, despite being officially protected for more than 30 years, many are in serious decline. Our endemic Maui's dolphin, now thought largely confined to the west coast of Auckland and Waikato, is on the cusp of extinction. The sea lion colony at the Auckland Islands has been decimated. A bottlenose dolphin population in Fiordland is critically endangered and another, in the Bay of Islands, is in trouble. Only a couple of hundred orcas still roam New Zealand waters, while the Bryde's whale population in the Hauraki Gulf is highly vulnerable.
"We really treasure them in our hearts but we are just not protecting them," says Peart, co-author of a new report which examines why our marine mammals are disappearing.
The Environmental Defence Society report, Wonders of the Sea: protection of New Zealand's marine mammals, cites a failure of leadership and legislation that collectively suggest a script for Yes Minister, the political satire that showcased the ability of lobbyists and self-serving bureaucrats to stymie progress.
The report, co-written by EDS oceans researcher Kate Mulcahy, exposes what amounts to buck-passing, lack of responsibility, toothless regulations and the triumph of economics over science. The systemic problems are more subtle than overt - legislation without practical powers split among agencies with silo mentalities and sometimes conflicting priorities, and a lack of public funding for much-needed research.
In this environment, a well-resourced fishing lobby has been free to conduct an obfuscation masterclass to make Yes Minister's Sir Humphrey Appleby blush, running rings around bureaucrats, politicians, scientists and conservationists. And Government agency the Department of Conservation, which the report argues should be taking the leadership role, is cast as growing weaker as the pressures on species have strengthened.
When the Marine Mammals Protection Act was passed in 1978, New Zealand was hailed as world-leading. Its main mechanism for helping threatened marine mammals is for DoC to prepare a population management plan, which can include measures such as limits on fishing by-catch (marine life accidentally caught in the hunt for fish).
In 34 years, no population management plan has been put in place.
Preparing the plans has proved tortuously complex and, as a final hurdle, they need the co-signature of the Minister of Fisheries (now the Minister of Primary Industries). A management plan for Hector's and Maui's dolphins failed partly because the fishing by-catch limit would have to be set at zero - an unenforceable target. Work on a plan for sea lions began in the late 1990s but took eight years to complete. In 2009, the Director-General of Conservation shelved the plan because it was out of date. Over that period, the sea lion was reclassified from nationally threatened to nationally critical.
DoC has instead tried non-statutory threat management plans but these rely on industry co-operation and the necessary compromises have weakened protection measures.
Fishing threats have, by default, been managed by the fisheries ministry (now merged into the MPI), whose "sustainable management" focus aims to allow continued fishing of commercial stocks. The Fisheries Act has no specific goals to protect marine mammals and, like the MMPA, no specific powers to minimise by-catch.
The report contrasts our regime with the United States, where regulations set a goal of zero by-catch and where by-catch is monitored and with Australia, which requires fishers to reduce bycatch to a minimum. Here, the only marine mammal for which a by-catch limit has been set is the sea lion.
Marine mammal sanctuaries, another weapon under the MMPA, have been undermined by allowance for commercial fishing and the Government's preference for using the Fisheries Act to limit by-catch.
The report says DoC and MPI have different cultures and values and have at times struggled to work effectively together.
Other risks, such as toxic run-off, oil spills and vessel speeds, are managed by councils and the Ministry of Transport respectively.
It adds up to a protective regime with as many gaps as a discarded fishing net. Alongside this is the scientific uncertainty which stems from inadequate research funding. Again by default, most research on marine mammals has been left to universities with funding for little more than population counts by PhD students.
"DoC is grossly underfunded and conservation science in general is grossly underfunded," says Dr Rochelle Constantine, a marine scientist at Auckland University.
She praises DoC for funding surveys of the critically endangered Maui's dolphin in 2010 and 2011 which led to the population estimate being further slashed to around 55 adults. "But no one else is stepping up to fund more research."
A likely consequence of it all is the extinction of Maui's dolphin, which risks putting New Zealand's environmental reputation on a par with China's - the last country to preside over the loss of a cetacean, the Yangtse River dolphin.
Maui's was confirmed as a genetically distinct sub-species of Hector's dolphin only a decade ago, though scientists had long known the population off the North Island west coast was in trouble. Physically identical, distinguished by their blunt beak and rounded dorsal fin, they are among the world's smallest dolphins and prefer shallow, coastal waters and harbours. The population was once plentiful as far south as Wanganui but is believed to have suffered catastrophic collapse since the 1970s. While bacterial disease, shark predation and land-based toxins are possible contributors, scientists believe death from entanglement in set (gill) net fishing is the main culprit, though more research is needed.
"New Zealand just needs to decide," says Constantine. "Do we want Maui's dolphins around or do we want to be the next country to lose a cetacean?
"If we think fishing is more important than the Maui's dolphin, that's fine. If not, we have to give it our best shot at helping the Maui's dolphin survive."
Otago University scientists Liz Slooten and Steve Dawson first alerted agencies to the dangers of set nets to the Hector's dolphin population off Banks Peninsula in the mid-1980s. While the newly created DoC moved quickly to establish a marine mammal sanctuary off Banks Peninsula, subsequent gains have been fraught and responsibility for controlling fishing has passed from DoC to MPI.
It's simplistic to portray DoC as marine mammal saviours rendered powerless by underfunding and MPI and the fishing industry as the evil empire - and the EDS report does not do so. New Zealand believes fishing for economic gain can be managed to keep commercial stocks and by-catch to sustainable levels. But with the failings of the MMPA, the Fisheries Act has held sway. It includes no obligation to protect marine mammals and is weak on minimising bycatch.
When fishing restrictions are suggested, it's understandable that the industry raises an outcry over the the threat to livelihoods and businesses - given the lack of scientific certainty about the causes of species' decline. The industry has used scientific doubt to routinely challenge fishing bans or limits, succeeding as often as not.
In 2002, a ban on set nets out to four nautical miles to protect Maui's dolphins from Maunganui Bluff (north of Dargaville) to just north of New Plymouth was overturned. In 2008, the industry sought a judicial review of a threat management plan which extended protection for both Maui's and Hector's dolphins. This delayed for three years efforts to extend the restricted set net area for Maui's dolphins out to seven nautical miles.
Measures to help the Auckland Islands sea lions, where a squid fishery operates outside a marine reserve, have run into the same hurdles - the closure of the fishery in 2004 was overturned by the Court of Appeal. The report says the legal challenges may have had a chilling effect and, with the squid fishers developing "escape devices" for sea lions caught in nets, fishing has been allowed to increase.
Tour boat operators have also used the courts to prevent DoC limiting their activities and DoC has been reluctant to introduce moratoria without hard evidence there is a problem.
Seafood Industry Council spokesman Don Carson says the sea lion's decline since the 1990s has been "far greater than our severest critics could account for. We don't know where the responsibility for that recent decline is but we know diseases can knock the hell out of the population. Fishing is being used as the most convenient explanation. Fishing is something you can see humans doing, something you can blame."
The industry is using a similar line to fight fresh moves to extend protection for Maui's dolphins southwards past Taranaki. It says sharks are a possible killer while land-based toxins and oil spills and bacterial diseases such as brucella can affect dolphin fertility.
"If we're going to make it a national priority to preserve Maui's dolphins as a species then we should be examining all aspects and identifying the real culprits in the decline," says Carson. "But the work that's going on is all about restricting fishing."
Constantine says the effects of pollutants have been looked at and by-catch in nets is accepted as the biggest threat to the dolphins. "No one's saying you can't fish. We're just saying 'go back to dolphin-friendly methods'."
While the industry demands fact-based decision-making, it is not averse to distorting the evidence. Bycatch of protected species is hugely under-reported (Otago's Slooten says research on the South Island east coast suggests only about 1 per cent of dolphins caught since 2008 have been reported). Yet, when a Taranaki fisherman did report a dolphin entanglement in January, the industry claimed this was the first reported fishing-related dolphin death in the area for 25 years.
That death and sightings of Hector's dolphins in the area prompted an interim extension in July of the set net ban as far south as Hawera (though only out to two nautical miles). Taranaki fishermen claimed it would "cost 40 to 50 jobs and $15 million in revenue". MPI estimates the annual economic impact at $420,000. The interim moves are to allow a review of the threat management plan, with final decisions expected by Christmas.
In identifying the problems, the EDS report finds solutions: strengthen the Marine Mammals Protection Act to allow DoC to regulate particular activities; give DoC the resources it needs to take a leadership role; require DoC to prepare recovery and management plans when species are threatened; require other agencies to follow those plans; set goals to reduce by-catch; and, perhaps most contentiously (and least likely), allow the Minister of Conservation to make final decisions without the Minister of Primary Industries' co-signature.
To raise the criticisms and suggested reforms with DoC and MPI is to run into the very mindset the report highlights.
Primary Industries Minister David Carter says changes to the MMPA are "not my responsibility" and that the Fisheries Act has adequate powers to manage the impacts on Maui's dolphins. The review of the threat management plan shows the two agencies can work jointly despite different statutory roles.
Carter echoes the fishers' line on probable causes: "For too long everyone has assumed that it's the fishing industry that's causing the demise of Maui's dolphin. But there are other suggestions including pollution. Work on identifying those other theats needs to be undertaken by DoC."
He adds that research funding "doesn't come out of my portfolio".
Ian Angus, who heads DoC's marine division, says DoC's marine responsibilities are vast and marine mammals are just one of a number of species being protected.
DoC needs to work with a range of stakeholders, as different legislation applies.
Asked to confirm that DoC wanted a larger extension of the interim protection area off Taranaki for Maui's dolphins, Angus said: "You need to speak to MPI. We gave advice based on our statutory responsibilities - the Minister took a decision."
The department is used to working in an environment of uncertainty, he says.
"The challenge is to make sure that uncertainty is highlighted to help decision-makers. We've got good resourcing, adequate to do some of the research we need to do. Whether it's enough? I don't know whether DoC would ever have enough from a research and science perspective."
Conservation Minister Kate Wilkinson says the Auckland Islands sea lions already enjoy the highest possible legal protection, and the Government "took immediate action earlier this year to protect Maui's Dolphins, including ordering an immediate review of the threat management plan".
Wilkinson says measures must be based on "sound science and evidence, not emotion and sloganeering". But her written response to Weekend Herald questions omitted to say whether she would support more funding for scientific research.
The species
Sea lion
One of only two marine mammals found only in New Zealand. Main breeding colony is Auckland Islands, a marine reserve and marine mammal sanctuary.
Nationally threatened in late 1990s, now nationally critical.
Squid fishery operates outside reserve; sea lions forage for squid inside and outside the reserve.
Squid fishing closures in 2003 and 2004 overturned by court action.
Bryde's whale
Hauraki Gulf population below 200.
Vulnerable to ship strike as they spend much time foraging near surface. Collisions thought responsible for at least 19 (probably more) of 42 reported mortalities 1996-2012.
Hector's and Maui's dolphin
Among the rarest and smallest dolphins in the world. Maui's population critically endangered; Hector's nationally threatened.
2011 estimate that only 55 Maui's adults remain, confined to part of west coast North Island.
Vulnerable to entanglement in set (gill) nets and trawling. Set net bans and other protection measures often delayed or overturned by fishing industry court challenges.
Hector's population off Canterbury also affected by dolphinwatching vessels.
Bottlenose dolphin
Fiordland sub-population critically endangered. Population in Doubtful Sound fell to an estimated 57 in 2010. Bay of Islands population also in decline.
Combination of factors suspected in Doubtful Sound, including increase in tour vessels and freshwater discharges from Manapouri hydro dam. Moratorium on new tour boat permits in Bay of Islands took 12 years.
