Dr Harry King of Saltas expects the Atlantic salmon selective breeding program to yield substantial benefits for Tasmanian growers.

Blueblood Atlantic salmon for Tasmania

A science-industry partnership is recruiting an elite pool of Atlantic salmon bloodlines to transform Tasmania’s A$170 million Atlantic salmon industry.

• 11 September 2006 | Updated 14 October 2011

• Unique fingerprinting
• Going to sea
• Numbers game
• Only the best

'The ideal fish would be square with handles,' Dr Harry King, operations manager at Salmon Enterprises Tasmania (Saltas), talks big on the benefits of selective breeding.

He expects a new program being established by Saltas and CSIRO through the Food Futures Flagship to bring A$20 million in benefits to Tasmania’s Atlantic salmon industry when the first progeny are harvested in 2009–10.

Subsequent benefits will be repeated in waves, with ten per cent gains in performance every three-year generation. Not bad for a combined investment of A$1 million a year.

But the goods won’t really be delivered by ‘carry-bag’ fish. Not initially at least.

'The selective breeding program will provide industry with the ongoing capacity to select salmon bloodlines best suited to Tasmanian farms and the tastes of Australian salmon lovers,' Dr King says.

'Improved growth rates will yield the greatest gains. With the industry valued at A$170 million a year, an expected ten per cent improvement in growth equates to production efficiencies of A$17 million a generation.

'Further benefits will flow from the selection of salmon bloodlines with increased resistance to amoebic gill disease (AGD), reduced incidence of early maturation, and improved carcase characteristics.'

Unique fingerprinting

Early in June 2006, Dr King took his place on the salmon ‘tag team’ at the Saltas hatchery near Wayatinah in Tasmania’s central highlands.

For five days the five-person Saltas/CSIRO team defrosted their fingers for long enough to fin-clip, tag, weigh and measure 6  000 one-year-old salmon, foundation members of the selective breeding program.

The fin-clipping exercise is unique among selective breeding programs worldwide. The tiny fin samples are used to ‘DNA fingerprint’ each fish and determine its family tree.

Without this capability, the 140 salmon families produced each year would have to be kept in separate tanks until large enough to tag, an expensive exercise that would subject the families to different ‘nursery’ conditions, making it difficult to compare their performance.

The Wayatinah tag team recorded a ten-fold difference in the weights of the young salmon. With 30–40 per cent of this variation attributable to genetic rather than environmental factors, this encouraging finding suggests great performance gains can be made by breeding from the best bloodlines.

Going to sea

In mid-winter 2006, half of the tagged salmon will be transferred from Saltas to a special seawater cage at Tassal’s marine farm in Port Esperance near Dover.

There they will be weighed and measured, and monitored for AGD and signs of early maturation several times before harvest (at 2.5 years).

AGD occurs when a microscopic amoeba attaches to the salmon’s gills. It is a significant health problem for Tasmanian farmed salmon, costing the industry an estimated A$17 million a year.

CSIRO project leader, Dr Nick Elliott, says an increase in the proportion of fish resistant to AGD infection is expected to reduce this cost and lessen stress on the fish, thereby improving their growth and health.

Early maturation is another cause of lost production that will count against salmon in the breeding program.

While Dr Harry King professes to love his long-jawed, mottled-brown broodstock at the hatchery, it’s the gleaming silver and black-backed youths that win the hearts of growers.

'When the salmon start to mature, their energy is diverted into gonad production rather than growth and meat production,' Dr Elliott says.

'Maturing fish are more vulnerable to health challenges, and their flesh quality is poor. So we’re aiming to reduce the proportion of fish that start to mature during their first year at sea.'

Numbers game

In its five-year establishment phase, the breeding program will fertilise, grow, measure and process tens of thousands of fish and generate hundreds of thousands of data records.

CSIRO quantitative geneticist Dr Peter Kube has the job of organising this information, and extracting its meaning.

Dr Kube says efficient, reliable instruments and programs for data capture, storage and analysis have been developed and will play a vital role in managing the numbers.

One example is a barcode system to identify and cross-reference all details and materials – eggs, sperm, fertilisations, tissue samples, and pedigrees – relating to each fish.

'The huge increase in computing power in the past 10–15 years has facilitated considerable advances in the capacity of such tools, and consequently the effectiveness of selective breeding,' he says.

Only the best

Each year, Dr Kube will analyse the performance of all the pedigreed fish to calculate ‘estimated breeding values’ for an elite group of potential parents retained at Saltas. Targeted matings are then be used to gradually raise the performance of successive generations.

Dr Kube’s analysis will consider the performance of individuals, siblings and parents (full-siblings have, on average, half their genes in common), and all their other, more distant, relatives.

'The parent selection also depends on an economic weighting given to each selection trait that helps to achieve the best overall outcome for growers,' Dr Kube says.

'In this way commercial selective breeding is a blend of science and economics, a management tool that can be continually adjusted to meet changing market needs.'

Progeny from the breeding program will be provided by Saltas to Tasmanian salmon growers as smolt for commercial production, and to hatcheries as eggs and young fish (to smolt stage) for growing into broodstock.

Will they be square with handles? Probably not. While the processors might be keen, the marine biologists have concerns about their aerodynamics.

Read more in the An Atlantic salmon selective breeding program for Tasmania brochure.