'Poor' season for Rangitata River salmon fishery, Fish and Game New Zealand says
A fisherman who has been visiting the same spot for 40 years says he's never seen the Rangitata River mouth so absent of fish.
Salmon catches at the Rangitata River mouth have been poor in what may be the worst salmon run on the river in recorded history, Fish and Game New Zealand suggests.
Fish and Game says the drop reflected a pattern in other South Island rivers and that the losses may be happening at sea.
But its position has been challenged by long-term angler Peter Ritchie who says he believes the decline is linked to the development of irrigation raceways - a claim their developer says does not stack up.
The Rangitata Huts fisherman said he had been fishing at the river mouth since 1937, when he was 7-years-old, and he had never seen the river so absent of fish.
By Monday, eight salmon had been caught at the river mouth since October 1. The tally is kept on a public board monitored by an angler Bill Whipp.
Ritchie called the haul "pathetic": "Normally, we have over a 100 caught before Christmas."
The catch rate had filtered through the angling community. The huts and camping ground appeared to host fewer fishermen than in previous seasons, he said.
"We have always had fish in the river."
Last fishing season, 171 catches were recorded, he said.
He blamed the development of nearby irrigation ponds for the drop, noting he had seen smolt in the ponds. He wanted the smolt trapped daily and returned to the river.
"I am very concerned about this."
Central South Island Fish and Game officer Mark Webb said there were salmon in ponds in the South Rangitata Irrigation Scheme after a flood during the scheme's development, but there were few fish in the ponds, Webb said.
About 250,000 fish moving down the river had contact with the fish screen, and about five per cent - 12,500 fish - ended up in irrigation raceways. The rest - some 237,500 fish - went out to sea, he said.
Webb was confident the fish screen was effective and believed what was happening out at sea may explain why so few were coming back through, Webb said.
There were huge numbers of kahawai in the sea which were having a significant impact on juvenile fish, he said.
He noted the salmon season was also poor at the Opihi, Orari, Waitaki, Rakaia, and Waimakariri rivers.
"Throughout history, for as long as there's been salmon runs ... generally what happens in one river, it's happening in all."
This may be the worst salmon run on record, but that would not be known until spawning counts start in June, he said.
The Rangitata South Irrigation Scheme was commissioned in October 2014. It was designed and built by Rooney Earthmoving.
Owner Waimate businessman Gary Rooney said the fish screen was tested by Fish and Game and was "fully compliant, and it always has been".
The scheme had been operating for less time than the three-year life cycle of a salmon. Salmon go to sea when they are born and return as adults three years later, he said.
"How on Earth can we make any difference to the fishery returns at this point?"
Any effect the scheme may have on the salmon run could not be measured right now, he said.
Asked about the fish getting into irrigation raceways, he said the numbers were very low: "We don't have any concerns."
Rooney, who is also an angler, said he spent more than $1 million developing a salmon spawn raceway as part of the consent. Some 60,000 smolt were put through the system this season.
"I love my fisheries. I'm there to enhance them, not wreck them."
Environment Canterbury southern zone manager Michael Hide said, in an emailed statement, ECan was aware of fish in the Rangitata South Irrigation Scheme's ponds as a result of the structure being "over topped" in the scheme's development, but did not hold any concerns about the fish screen's effectiveness.