King shag enters Marlborough Sounds salmon farm wrangle
The Marlborough Sounds is home to one of the world's rarest seabirds, but if a proposal to relocate salmon farms in the region goes ahead their future could be grim, an ornithologist says.
The king shag is confined to the Sounds, and despite survey methods changing over time its population appears to have remained relatively stable since it was first counted in the 1770s.
However, local ornithologist Rob Schuckard is worried the king shag, with a population of about 900, could end up being "scooped out of the water" if the Government's salmon plans go ahead.
A dangerous species of algae which could destroy the water-proof coating of their feathers had already been spotted in the Sounds, and could spread, Schuckard said.
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"Effectively the birds can get waterlogged. It's getting through the skin. The birds are at risk of getting hypothermia and are not well able to fly back to the colony," Schuckard said.
There was a danger birds would not even be able to swim to shore, and people might be left scooping the king shags out of the water, Schuckard said.
"This is a risk that we cannot neglect."
The particular strain of algae, akashiwo sanguinea, had not been specifically linked to salmon farms, but the question was how the algal blooms would behave when the water was enriched due to salmon farm waste.
"They are already occurring in the Tory Channel. If they start to bloom in the feeding area of the king shag, if that species is basically starting to bloom in the Pelorus Sound, or in the outer Queen Charlotte Sound, then we may lose a major part of the population of the species."
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New Zealand King Salmon sustainability manager Mark Gillard said he was aware of the algae which affected the birds' feathers, but it was naturally occurring, along with hundreds of other types of algae, some of which were toxic.
Chief executive Grant Rosewarne agreed, describing the toxic algae as an "accident of nature".
Rosewarne said King Salmon funded the latest monitoring survey of the bird, and was committed to protecting king shag. The last thing the company wanted to do was endanger it, he said.
The king shags' prey were benthic-feeding fish which lived at the bottom of the sea such as witch flounder, opal fish, lemon sole, and New Zealand sole, Schuckard said.
Although the bird lived in colonies in the rocky outer Sounds, it flew into the inner Sounds everyday to dive for food - and other types of algae could affect its food sources.
With increased nitrogen in the water due to more salmon farm waste it was possible those blooms would intensify.
"Basically the Marlborough Sounds has very clear water so a lot of deep light penetration is taking place," Schuckard said.
"That means that there is a lot of bottom activity, let's say of fish, or crayfish, of all things living on the bottom. That is the environment of the king shag."
Algal blooms blocked the light, potentially threatening the king shag's hunting environment.
Rosewarne said evidence from Cawthron Institute showed the witch flounder, a significant food source for the king shag, would thrive once the current low-flow sites were abandoned.
The worms the witch flounder liked to eat lived beneath the waste created by salmon farms.
A report to MPI from Statfishtics scientist Paul Taylor on the prey of the king shag said witch flounder were the bird's main food source.
It fed on both crustaceans and small "pelagic" fish which lived in the middle of the sea, between the sea floor and the surface.
The small fish would not be affected by the salmon farms if they went ahead, Taylor said.
"Any reduction in the availability of [the flounder's] prey resulting from the relocations would be offset by recovery of the vacated sites, but effective recovery would probably require several years," Taylor's report said.
However, Schuckard said Taylor was greatly exaggerating the importance of the witch flounder.
"I'm not saying it is not important, but it is part of a wider collection of bottom-living fish," he said.
Schuckard said one of the reasons the bird was vulnerable was it was an unusual "hybrid of diving and flying". With powerful legs and small wings, it could only fly about 25 kilometres at a time.
The latest count in 2015 revealed 839 birds in the Marlborough Sounds, which was more than previously counted, but Schuckard said he strongly believed that was due to survey methods improving.
The management of the species was in its infancy and it was "simplistic" to say the species was doing alright, he said.
The king shags' unusual physiology meant it could not change its feeding patterns, so people had to be particularly careful about not changing their domain, Schuckard said.
A lot about the species was still unknown.
"They can have two chicks, that is the impression they get from a far distance. However [as to whether] they can raise two chicks in one breeding season, I would absolutely not be able to answer that question."
"We need to do more on this species, we need to invest in this species. We need to not run with the crowd," he said.
Schuckard said although DOC had provided valuable assistance when it came to surveying the bird, he was puzzled by the department's silence on the MPI proposal.
He was presenting his submission to an independent hearings panel on May 8, and was expecting "a lot of tough questions", Schuckard said.
Eko-Tour owner Paul Keating said every year about 10,000 people from around the world came into the Marlborough region to see the bird.
King Salmon did not seem to realise the popularity of the bird, he said. It lived in the area for centuries and there were Maori legends around its arrival in the Marlborough Sounds.
One legend said the king shag, Te Kawau-a-Toru, arrived with the first Polynesian explorers, and died in the area called French Pass after plunging his wing in the water, and breaking it.
The king shag had a "huge following" among birdwatchers worldwide, and he promoted it not long ago at an international bird fair in London, Keating said.
Many community groups and individuals cited the effects on the king shag as a reason why the salmon farms should not be relocated.
- The Marlborough Express