Salmon don’t grow on trees
Releasing salmon fry into the wild has become commonplace, but at East Coast South Island salmon hatcheries operations, a strong effort to increase the common sense and science of the operation is in place.
The parents are harvested with great care and the capture of eggs and milt is to a planned timetable. The results make it all worthwhile.
Salmon runs in East Coast rivers resulted from salmon releases from the government hatchery originally established on the Hakataramea River. Since about 1901, salmon have ranged widely, helped by hatchery releases in Dunedin, Central South Island, and North Canterbury.
The surprise establishment of salmon in Otago Harbour resulted from a successful release made by the late Ron Dougherty, through the generosity of MAF. Today, Otago Harbour is a proud salmon fishery that extends right into the centre of Dunedin – rightly known as Salmon City of the Southern Hemisphere.
Recently 21,700 smolt were released into the Leith River, with the overall release this calendar year of about 58,700 smolt. A further release of about 45,000 smolt from the Dunedin City Salmon Trust hatchery was made by the Otago Salmon Anglers Association last week.
The recent release of 60,000 salmon smolt from McKinnon’s Creek hatchery (on the Rangitata River) is a good example of how hatchery practices are gaining improved results.
Three weeks ago I saw a release and dedicated hatchery volunteer Bill Whipp showed me a raceway containing 35,000 of the 100gsmolt.
‘‘We have found this to be the manageable capacity in this raceway. They didn’t do as well last year when we had more smolt,’’ he says.
The daily inspection of smolt in the raceways has helped maintain the health of these small fish.
‘‘We run a tight programme and all the hatchery volunteers are vigilant to ensure smolt health.
‘‘From the capture of adult male and female salmon, we strip eggs and milt and fertilise the eggs on day one,’’ he explains. ‘‘After 15 days they eye up, although this may depend upon water temperature and at some hatcheries the eyed-up condition is known to take as many as 30 days.’’
Throughout this time dead eggs are removed from the trays containing tens of thousands of eggs, and for about 44 days the egg sac nourishes the alevin as it slowly develops into a small fish.
If the eggs were hatching in the wild, these small fish would find themselves submerged beneath many centimetres of shingle – the protective covering their parents provided over the redd – but in the hatchery environment they face little effort to reach surface water.
Bill Whipp says the hatchery achieved 95 per cent egg fertilisation this year and has shared this bounty, including 170,000 eggs going to Mesopotamia.
A successful hatchery demands careful observation and attention throughout the egg stage; a regular feeding programme of quality feed thereafter, water quality consideration, and gentle handling that avoids stressing the fish.
In North Canterbury, releases have come from hatcheries at Montrose (on the upper Rakaia River), Peacock Springs (in Isaacs Quarry on the south side of the Waimakariri River) and Silverstream (north side of Waimakariri River).
North Canterbury Fish and Game has released 60,000 smolt into the Waimakariri River and 60,000 smolt into the Rakaia River.
A huge effort by the New Zealand Salmon Anglers Association and the Rakaia River Fishing Promotions team and volunteers has seen a very significant number of salmon eggs implanted in the region.
I understand some 400,000 eggs have been implanted in Scotty boxes, incubators, alevinators, and through barrel planting. This is where the streambed is excavated a short distance and a barrel placed vertically over the site. About 2000-3000 salmon eggs are placed into the still water within the depression and shingle heaped over the site to create an artificial redd.
About 250,000 eggs were planted in the upper reaches of the Waimakariri and Hurunui Rivers, and 150,000 eggs went in the upper reaches of the Rakaia River.
Considering something like 3000 anglers a week fish below the old Waimakariri Bridge and in the river mouth for salmon, and that 20 per cent of this season’s Waimakariri catch were finclipped fish, it suggests these fish benefited anglers before wild fish returning as well as augmenting the whole season.
‘‘Without these hatchery releases and the ova planting enhancement, wild salmon returns could have been as low as 30 per cent of current returns,’’ says Ron Stuart, a keen salmon angler of 30 years, and a former president of the association. He leads the salmon enhancement activities.
Stuart says earlier this year a team from the association waterblasted a 50m section of the bed of Hacketts Stream and during the spawning season it attracted nine natural salmon redds.
Also on this stream, the association has established a large alevinator with approximately 40,000 salmon ova in traditional Scotty boxes, and says anglers are grateful to the property owners through which this stream runs, for their co-operation and support for the salmon fishery.’’
So next time you think about salmon, think about the few who do so much to ensure the salmon resource is there for Otago, Central South Island, and North Canterbury anglers. It’s three regions working together for the common goal . . . more salmon in the rivers and harbour.
The reward: Brett Bensemann with a limit bag of salmon from Dunedin Harbour.
Fish planting: Volunteers use barrels to create protected salmon redds in North Canterbury.
Nursery: Incubators in sequence in North Canterbury spawning water.
Feeding out: Keen volunteer Bill Whipp looks after smolt in the raceway on the Rangitata River.