Shag enters salmon 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 waterproof coating of their feathers had already been spotted in the Sounds, Schuckard said.

‘‘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.’’

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.

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.’’

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.

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.

Many community groups and individuals cited the effects on the king shag as a reason why the salmon farms should not be relocated.