A large, elongate and cylindrical eel. Maximum length is 1,100 mm and maximum weight is 3.2 kg, but most individuals are <700 mm long and weigh less than 400 g. The dorsal, anal and caudal fins are joined, with the dorsal fin commencing just in front of, or level with the anal fin. It is usually coloured a uniform olive-green to golden-brown dorsally, with a whitish or sometimes silvery-white belly. The mouth is large with distinct and numerous teeth. The mouth is large, but unlike that of the Long-finned eel, does not extend well behind the eye, instead finishing below the eye.
Short-finned eels formed a valuable fishery for Aboriginal people for millennia in the coastal Darlots Creek system in Vic with eels harvested and farmed via complex systems of stone-walled trap and channels and ponds. This species lives in a variety of habitats including rivers, lakes, and swamps, generally with low or no flow. It migrates to sea to spawn, with the spawning location considered to be the Coral Sea between Fiji and Samoa. Spawning is thought to occur in November– March. The larval eels are washed down the east Australian coast by the East Australian Current. As the leaf-like larvae (leptocephali) approach the continental shelf they metamorphose into the traditional eel shape (glass eels) and the unpigmented glass eels enter fresh water in spring–summer and then transform into pigmented elvers. The larvae and glass eels take about 7-9 months to migrate from the spawning grounds to the Australian east coast and are from 170-250 days old when they enter freshwaters (depending on spawning month and on how far south they enter). The glass eels and elvers then migrate upstream to the upper reaches of rivers, where they may remain for 20 years or more before a return migration to their marine spawning grounds to breed and then die. Previously it was assumed that adults rapidly moved through estuaries when moving from freshwater to spawning areas, but recent research indicates that individuals spend from 1 to 305 days (median: 77 days) in the estuary. Movement from the estuary into the sea is influenced primarily by moon phase and water temperature, with this movement occurring in late summer – early autumn. Recently eels from southern Australia were tracked with pop-up satellite archival tags and were found to migrate to the Coral Sea by accessing deep water off the Australian coast. Travel routes of tagged fish were either directly east via Bass Strait, or taking the short-cut to deep water by going south-east around Tasmania.
Adults in Australia occupy a well-defined home range of about 400 m, but in a small freshwater lake in New Zealand the average nightly foraging range of adults was 22,780m2. Females dominate the catch in freshwater environments and males are more abundant in downstream, estuarine areas. Males are sexually mature at 14 years and females at 18–24 years. A voracious nocturnal predator, the Short-finned eel eats a variety of fish, crustaceans, molluscs, and insects. In a tributary of Lake Jindabyne in southern NSW Short-finned eels preyed on stocked salmonids such as Rainbow trout and Brook charr, with 22% of eels captured having small (30–70 mm) Brook char or Rainbow trout in their stomachs. Only eels >400 mm TL consumed trout, with all trout in eel stomachs being <130 mm length. About 25% of larger trout had damaged fins or scars, indicating predation was attempted on larger fish.
Short-finned eel occur both in Australia and New Zealand, with recent genetic analysis suggesting different subspecies in each country. In Australia it is primarily a fish of coastal streams outside the Basin, though there are occasional records from inland streams. Most inland records are assumed to be of fish translocated from coastal streams, but some represent natural dispersal events. There are occasional records in the Basin from the upper Murrumbidgee River with these individuals possibly translocated via the Snowy Mountains Scheme or more likely translocated from south coast streams by anglers. There are historic and recent records from the lower Murray in SA. The species has also been introduced into the Wimmera River Basin in Vic via water transfer from the Glenelg Basin, and records from the Goulburn catchment represent escapes from an aquaculture facility. No Short-finned eels were recorded in the Sustainable Rivers Audit monitoring in the Basin from 2004–2013 or in the MDB Fish Survey from 2014/15–2021/22.
None known in MDB, but in coastal systems barriers to downstream migration of adults, particularly hydroelectricity schemes and associated turbines are cause for concern. Coastal wetland drainage and conversion are also threats. The extended period of estuarine occupation before undertaking spawning migrations increases their vulnerability to fishing during this period. Changes to oceanic currents associated with climate change will also affect larval dispersal.
Allen et al. 2002; Arai et al. 1999, 2004; Béguer-Pon et al. 2017; Beumer 1979a, 1996; Crook et al. 2014; Jellyman 2016; Jellyman & Crow 2016; Koehn & O’Connor 1990; Koster et al. 2021a; Llewellyn 2011; McKinnon 2002; McKinnon et al. 2002; Rose et al. 2016; Shen & Tzeng 2007; Shiao et al. 2001, 2002; Silberschneider et al. 2004; Sloane 1984a,b.
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