This time they are killing hoiho (yellow eyed penguins), driving the species to extinction.
That is if you believe the alarmists claims from the anti-commercial fishing lobby.
The unsubstantiated claim by Forest & Bird is that a decline in nesting numbers on Codfish Island west of Stewart Island - from 24 to 14 - is entirely due to drowning in commercial set nets.
F & B calls for "honest conversation" about this "catastrophe" before demanding Government action to "save our hoiho from extinction".
Anyone reading that would assume the beloved bird that adorns our $5 note is about to be wiped out.
That is simply not the case.
What the emotive F&B media campaign fails to mention is that the great bulk of the yellow-eyed penguin population - about 85 percent - inhabits the sub-Antarctic Auckland and Campbell islands where no set netting occurs in coastal waters out to 12 nautical miles. In fact no fishing occurs in those waters full stop. The estimated total penguin population is 1700 pairs.
On the mainland, the estimate for the southern east coast is 246 pairs, a 6 percent decline on the previous year's count of 261.
The penguin protectors' motives are admirable but the Trump-style truthiness approach is disingenuous.
The tactic, which we are familiar with by now, is to take an issue of legitimate concern, highlight one aspect of it, take it out of context, ignore any evidence that contradicts the narrative and put out a one-sided media statement for maximum impact.
The fact is research by Otago University's Dr Ursula Ellenburg does not conclude that fishing is the major cause of yellow-eyed penguin deaths. She found there are many threats to the species including climate change, habitat degradation, disease and predation. However, the research does say that, of any threat caused by fishing, set nets cause the most deaths.
Avian diphtheria remains a serious ongoing issue for the birds and can affect a large proportion of newly hatched chicks, according to the Department of Conservation.
Great white sharks, barracouta, fur seals, sea lions and leopard seals all prey on penguins.
Otago University marine mammal scientist Dr Chris Lalas says one threatened species (sea lions) preying on another (penguins) creates a quandary for conservation management.
On land, introduced mammalian predators including stoats have an impact on yellow-eyed penguin chicks and dogs are a threat to adult birds.
Fishing does pose some risk to yellow-eyed penguins. Industry takes a range of precautions to limit captures and is happy to discuss what measures can be implemented to assist further.
The Ministry for Primary Industries observed 25 percent of all commercial set net activity off Southland and the southern part of the east coast over the past 12 months and found no captures of yellow-eyed penguins, according to fisheries management director Stuart Anderson.
F & B claims the real number is likely to be in the hundreds.
Set netting within four nautical miles of land is already prohibited in much of the Southland Fisheries Management Area.
The fishing industry is not in denial.
Its activities do have an impact on the marine environment and its inhabitants, just as farming does on land.
It is the degree of that impact that is at issue.
The industry is committed to reducing that, a fact the environmental NGOs struggle to acknowledge.
Southern Inshore Fisheries and Fisheries Inshore New Zealand, in conjunction with MPI, have developed 10 golden rules to reduce risk to penguins and shags from setnet fishing.
And here's a suggestion to make more progress.
Instead of pillorying the seafood industry with half truths, seek a dialogue first, avoid simplistic claims, put the issue in context, show respect and goodwill to other parties and work to find compromises to reach a satisfactory solution.
Or maybe we should ban sea lions and great white sharks to fully protect penguins.
And do away with dogs too.