A medium sized fish that is very similar to Brown trout, but with a smaller mouth that does not reach back past the eye, a more deeply forked tail and slender caudal peduncle. Maximum weight 38 kg in their native range; commonly 1–3 kg in Australia. Unlike Brown trout, it does not have an orange margin to its adipose fin, and the spots on the sides are composed of small ‘x’-shaped marks.
A fish of cool streams and lakes, the Atlantic salmon has not established significant populations in Australia. Its ecology is very similar to Brown trout and it is a popular species for aquaculture. It is stocked to provide recreational fisheries in NSW, but returns are marginal. Overseas the species is variable across its range in its freshwater habitat use, length of residence in streams, and age at maturity. In Canada, young, stream-dwelling Atlantic salmon feed mainly on aquatic insect larvae such as mayflies, caddisflies, chironomids and stoneflies. Adult salmon on their spawning run do not feed.
Adult salmon usually mature after 1–3 winters at sea, returning to streams to spawn from May–November, depending on the population. Average fecundity is around 10,000–20,000 eggs, depending on body size and population, with 1,300–2,000 eggs/kg of body weight common. The eggs are large (5–7 mm diameter) and are laid in a gravel nest (‘redd’) excavated by the female, usually in a gravel-bottomed riffle. The young salmon parr remain in freshwaters for 2 or 3 years before migrating downstream to spend several winters in the ocean before returning to spawn. In some large land-locked lakes in North America, the species has established self-sustaining populations. Reproductive biology is variable and fish may spawn several times in a season, or for consecutive years. There is a large body of scientific literature on this species in its natural range, due to its declining status, but very little has been published on its habits in Australia.
Due to its limited distribution within the Basin, little is known of the impacts of Atlantic salmon on native fish. However, as a large predatory species, it can be expected to consume small native fish such as galaxiids and small perch, as well as native crayfish.
The Atlantic salmon is native to rivers draining to the North Atlantic Ocean. It was first introduced to Australia between 1864 and 1870 when it was released in Tas and Vic, but with little success. 100,000 eggs were imported from Canada in February 1963 and eggs subsequently hatched in a temporary facility at Sawpit Creek in Kosciuszko National Park, with 17,500 fry produced of which 9,000 were released in Micalong Creek (a tributary of the Goodradigbee River) in October 1963. Further imports of 100,000 eggs from Canada occurred in 1964 and 1965. These 3 importations formed the basis for the ongoing hatchery breeding program in NSW, which attempted (unsuccessfully) to establish land-locked self-sustaining populations in lakes in the Snowy Mountains. By 1972 only 36 ripe female broodstock remained, and it is from these fish that the successful Atlantic salmon aquaculture industry in Australia is derived. The species was regularly stocked in NSW into Lake Burrinjuck and its tributary the Goodradigbee River until 2003 and is still stocked in Lake Jindabyne and Khancoban Pondage in NSW. Approximately 25-50,000 fry have been stocked annually into Khancoban between 2005 and 2020. The species is not stocked in the MDB outside of NSW. No natural recruitment occurs in NSW and the species’ continued presence in water bodies depends completely on the stocking program. Other locations in Australia where Atlantic salmon are stocked include a handful of locations in Tas as well as Lake Purrumbete and Lake Bullen Merri in Vic. The species is sea-ranched in pens in Tas, and stocks have escaped from trout farms into the Acheron River system in Vic during recent floods. No individuals were recorded from the Sustainable Rivers Audit (2004–2013) or the MDB Fish Survey (2014/15–2021/22).
Birnie-Gauvin et al. 2019; Brinsley 2011; Cadwallader 1996; Clements 1988; Davies & McDowall 1996; Faragher 1986; Gilligan 2005a; Klemetsen et al. 2003; Llewellyn 2015; Scott & Crossman 1973; Stevens et al. 2019.
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