by Ann van Engelen

The southern hemisphere’s only known population of the mysterious sockeye salmon have been spawning in the Mackenzie Country’s alpine rivers.

In the Twizel River, the sockeye were passing under the State Highway 8 Bridge near Twizel township. The sight of hundreds of the fish moving up the river and spawning right below the bridge became a popular site for tourists and locals during the spawning season recently.

“For many, the chance to see these fish migrate is a once in a lifetime event with dozens of people crowding the bridge to look at them,” says Central South Island Fish & Game Officer Jayde Couper. “The sockeye are highly visible, often bursting out of the water in a shower of spray as they scramble across the riffles in their search for the ideal spot in the riverbed to lay their eggs.” 

The Mackenzie Country sockeye is the only population of the species in the southern hemisphere. The salmon are in all the lakes in the Mackenzie Country.

“The species were originally released in 1901 as an attempt to create a sea-run salmon canning industry. The attempt failed when the sockeye never ran to the sea, leaving the chinook salmon to become the basis for the South Island’s successful salmon fishery,” says Jayde.

Sockeye were thought to have died out in the late-1980s. Fish & Game had looked for them but they could never be found. Around 2005, they started receiving reports of them spawning once again. It is believed the fish were possibly in lake Ohau.

“Now the sockeye can be found in their thousands heading upstream at this time of year to breed. Their comeback from the verge of extinction continues and this year the spawning effort appears to be widespread and the numbers are reasonably high.”

Sockeye have been observed in almost all of the Lake Benmore tributary rivers and streams, most notably the upper Ahuriri River and its tributaries, Lower Ohau River and its tributaries like the Twizel and Fraser Rivers, the Tekapo River and its tributaries like the Mary Burn and Forks River.

Jayde says sockeye are also turning up in areas where they were not thought to exist.

“The other interesting observation this year is the Lake Pukaki population is flourishing, yet Fish & Game staff only heard about them existing there last year.

“There had not been any confirmed reports of sockeye in Lake Pukaki for decades, now this year there are around a thousand spawning fish in just one of the lake’s tributary streams.”

Jayde warns people against disturbing the fish.

“It is an offence under the Conservation Act to disturb spawning salmon — you can’t catch, net or spear the fish, or even walk in the riverbed and trample their redds, or nests. This is why the Twizel bridge site is so popular, as people can watch the fish from above without disturbing them.”

Jayde Couper, Central South Island Fish & Game Officer

Despite their numbers, sockeye are rarely caught by anglers as they filter feed on plankton and are not normally attracted to an angler’s lure.

They live in the lakes and are only seen when they run the rivers and streams to spawn. “Sockeye’s main value is as a food source for native fish, trout and chinook salmon and this helps to maintain the productive and popular lake fisheries at Ohau, Benmore and Aviemore,” says Jayde.

Sockeye are filter feeders and they are like a whale and eat the plankton, which is why they are hard to catch.

“Because they were thought to be extinct, Fish & Game didn’t count the sockeye for a number of years.

“The re-emergence of the species means the organisation is now developing a field method capable of estimating the total Upper Waitaki catchment spawning run.

“There are too many salmon and not enough time and resources to count them all. The fact sockeye appear to have come back from the dead is heartening and a positive sign of the health of the fishery in the Waitaki Lakes. “The real benefit to anglers is the food source they supply in the form of their juvenile offspring. Trout and chinook salmon will fill their guts with juvenile sockeye given the opportunity.

“With thousands spawning throughout the Mackenzie Basin this year we anticipate that trout in lakes Benmore, Pukaki, Ohau and Aviemore will be well fed come next summer. “This phenomenon was graphically illustrated back in 2009, when an angler discovered 26 juvenile sockeye salmon in the gut of their five pound Lake Benmore trout. 

“New Zealand’s sockeye won’t end up in supermarkets but Canadian and American sockeye are available in cans under the name Red Salmon.”