A species of penguins native to New Zealand may go extinct by 2043 if the population does not rebound.

New Zealand's yellow-eyed penguins have suffered a sharp decline over the past two decades. Researchers have found that the breeding population has declined by 76 percent between 1996 and 2015.

A new study, recently published in PeerJ, notes that climate change has been a contributing factor in the penguins' decline, but the main culprit may be human activity.

Climate Change Isn't To Blame

During the 1940s, rising water temperatures in the Kumo Kumo Whero Bay should have led to a decline in the local penguin population, but the research records of a local school teacher, Lancelot Eric Richdale, proved that the local penguin population thrived despite the changing environment.

Thomas Mattern, the study's lead author, argued that Richdale's data shows that we cannot blame the decline of native species solely on climate changes, as that can lead us to ignore humanity's own impact on wildlife.

"But if it was just climate change by itself the penguins would probably do quite well, they would adapt," said Mattern, an ecologist at the University of Otago. He explained that the changing climate is not the only thing to blame for the disappearance of a species, stressing that other factors such as regional pressures should be considered.

Unsurprisingly, one of the biggest problems facing the yellow-eyed penguin population and other forms of marine life is the fishing industry. Gillnets, a type of net that are hung vertically in order to catch fish by the gills, often end up ensnaring penguins and other local marine animals.

A study released in 2000 found that out of 185 autopsies conducted on New Zealand's penguins, 42 had been killed as result of gillnets. Fishermen admitted to accidentally killing 30 more.

Economic Costs

In 2015, it was reported that there were only 58 breeding pairs of penguins in New Zealand, down from 200 in past decades. Mattern warned that the loss of the penguins could greatly outweigh the economic benefits obtained from the fishing industries in that area.

"If you look at the economic value of the fish they are catching, they catch primarily really low-value fish that we then eat as fish and chips, as fast food," said Mattern, adding that after a rough comparison, they were able to ascertain that four Otago fishermen make a net profit of nearly 1 million New Zealand dollars, or about $688,000.

"Yet the penguins we have here, they bring in the tourism. And it's been estimated that just a single pair of penguins brings in $250,000 a year to the local economy," Mattern said. "Now, we used to have 200 pairs here - you do the math."