THREATENED SPECIES SCIENTIFIC COMMITTEE Established under the Environment Protection and Biodiversity Conservation Act 1999 The Minister’s delegate approved this conservation advice on 01/10/2015 Conservation Advice Maccullochella ikei eastern freshwater cod Conservation Status Maccullochella ikei (eastern freshwater cod) is listed as Endangered under the Environment Protection and Biodiversity Conservation Act 1999 (Cwlth) (EPBC Act). The species is eligible for listing as Endangered as, prior to the commencement of the EPBC Act, it was listed as Endangered under Schedule 1 of the Endangered Species Protection Act 1992 (Cwlth). The species is also listed as Endangered under the Fisheries Management Act 1994 (New South Wales) and Endangered under the IUCN Red List of Threatened Species Version 2015.1 (Wager, 1996). Description The eastern freshwater cod, family Percichthyidae, also known as the Clarence River cod, eastern cod, codfish, or cod (Harris and Rowland, 1996), is a large freshwater fish with a deep, elongate body, reaching a maximum length of over 1 m (Pollard et al., 2002, cited in Nock, 2009; Butler and Rowland, 2008) and a maximum weight between 40 and 50 kg (Merrick and Schmida, 1984; Harris and Rowland, 1996; Allen et al., 2002). Since the 1960s, individuals greater than 900 mm in length are rare (Merrick and Schmida, 1984; Harris and Rowland, 1996; Pollard et al., 2002, cited in Nock, 2009). Adults are generally olive-green to yellow-green in colour, with dark, and often reticulated, mottling on the back, tending to white on the underside, with some mottling extending underneath in some individuals (Harris and Rowland, 1996; Allen et al., 2002). A distinctive characteristic of this species is the relatively elongated white tapering filaments at the ends of the pelvic fins. These extend beyond the lower margins of the fins by between 1 and 2 cm (Allen et al., 2002; Butler, 2009). Distribution and Habitat From the 1800s to the early-1900s, the eastern freshwater cod was found in large populations in two large, separate, coastal river systems, the Clarence and Richmond river catchments, in northeastern New South Wales (Rowland, 1993; NSW Fisheries, 2004). The species was found in areas downstream of the tablelands waterfalls located in the upper parts of these catchments (Rowland, 1993; NSW Fisheries, 2004). In the early 1900s, there was a dramatic decline in the population occurring in the Richmond River catchment (Rowland, 1993), and the “naturally- occurring” population of the species is now extinct from the catchment, with the last authenticated capture of an individual from this catchment being in 1971 (J. Bell, pers. comm., cited in Rowland, 1993). The marked decline in numbers in the Richmond River catchment coincides with the construction of the north coast railway, in the years following 1926, which was closely constructed along the river course north of Casino (Rowland, 1993). Maccullochella ikei (eastern freshwater cod) conservation advice Page 1 of 9 The eastern freshwater cod also declined dramatically in the Clarence River catchment during the 1920s and 1930s after a number of significant fish kills (Rowland, 1993). The naturally- occurring population in Clarence River tributaries such as the Cataract, Rocky and Orara rivers, and the upper Clarence River itself, became very rare following the 1930s (Rowland, 1993) before stocking activities in the late 1980s to early 2000s (Nock et al., 2011). From the 1960s, the last remaining stronghold for the naturally occurring population of eastern freshwater cod within the Clarence River catchment had contracted to the Mann-Nymboida rivers catchment, which includes the Little Nymboida, Boyd, Aberfoyle and Guy Fawkes rivers (Rowland, 1993). Restocking programs from the late 1980s until the early 2000s saw over 300 000 captive bred fingerlings stocked widely across the eastern freshwater cod’s historical range, including the Mann and Nymboida rivers where there was a known, wild, self-sustaining population (Rowland, 1989; Faragher et al., 1993; Pollard and Wooden, 2012, all cited in Butler and Rowland, 2009; Nock et al., 2011). There are indications that this stocking activity may have contributed to a decline in genetic diversity amongst the largest remaining wild population in the lower Mann and Nymboida rivers (Nock et al., 2011). The Richmond River catchment and the upper Clarence and Orara rivers of the Clarence River catchment, which were, prior to the stockings, considered to be extirpated of eastern freshwater cod, are now considered to have reintroduced populations of the species (Nock et al., 2011). The success of these stocking events remains unclear as survival of stocked individuals seems inconsistent and there is uncertainty about the ability of these stocked populations to become self-sustaining into the future (Faragher et al., 1993; Pollard and Wooden, 2002, both cited in Butler and Rowland, 2009). The eastern freshwater cod reaches sexual maturity at between 4 and 5 years of age, and body weights of 0.7 and 1.5 kg (Rowland, 1996). The species is known to live and reproduce beyond 15 years of age, given that fish have been aged to 15 years at 865 mm in total length and that other adults have been recorded at lengths greater than 1100 mm (Butler and Rowland, 2008). The species spawns in late-August and early-September in the wild, when water temperatures rise from 16 to 18°C (Rowland, 1989, cited in Butler and Rowland, 2009). During the spawning season, males have been observed moving distances of up to 30 km to locate suitable spawning sites (Butler, 2009). Females deposit eggs onto hard surfaces, such as rocks, (Rowland, 1996) and in situ observations indicate a preference for clean hard substrates of bedrock, cobbles and large boulders under cover (i.e. not in open water), with post-spawn care being offered by male parents (Butler and Rowland, 2009). Hatching of larvae in the wild and under controlled conditions has been observed commencing after about seven or eight days and is completed by 12 days, if water temperatures remain above 17°C (Rowland, 1996; Butler and Rowland, 2009). After hatching, larvae have been observed in the wild remaining on the substrate at the nest, not swimming, for between 5 and 6 days, but then swimming away from the nest at between 10 to 12 days following hatching (Butler and Rowland, 2009). Under controlled conditions larvae commence feeding on zooplankton 12 days after hatching (Rowland, 1996). Adult eastern freshwater cod are considered to be top order predators in the systems they inhabit, with a diet that includes fish, crustaceans, frogs, aquatic birds and some terrestrial prey, including snakes (Rowland, 1996). Maccullochella ikei (eastern freshwater cod) conservation advice Page 2 of 9 Threats A number of historical events appear to have significantly contributed to the decline of eastern freshwater cod. These include habitat degradation and fish kills associated with dynamiting during the construction of the north coast railway in the late-1920s (B. Wilson, pers. comm., cited in Rowland, 1993; NSW Fisheries, 2004). In the late-1930s, residents in the upper Clarence River catchment reported the use of dynamite within the vicinity of Clarence River Gorge as a method for catching fish, but in effect killing thousands of fish (Daily Examiner, 1939). This non-selective technique is likely to have resulted in localised extinction of the eastern freshwater cod. Overfishing of the species across its range was once highly likely to be a threat (Rowland, 1996), and would have placed pressure on stocks of the species after the initial declines the species experienced in the 1930s. Capture by recreational fishers has been prohibited throughout its historical range since 1982, and a total fishing ban has been imposed on the Mann and Nymboida rivers from August to October each year to protect breeding individuals in this area (Butler, 2009). Fish kills involving many individuals of this species were observed in heavy floods during the 1920s and 1930s (D. Machin and S. King, pers. comm., cited in Rowland, 1993; NSW Fisheries, 2004), which had followed long dry periods, extensive bushfires and then heavy summer rains (S. Adams, K. Murphy, F. Winters, pers. comm., cited in Rowland, 1993). In particular, severe bushfires throughout the Clarence and Richmond river catchments seemed to have been most significant in late-1936, after a catastrophic drought in the region earlier that year (Farmer and Settler, 1936; National Advocate, 1936; NMHMA, 1936; SMH, 1936a, b, c and d; Uralla Times, 1936). In both the Richmond and Clarence river system catchments, agricultural development is extensive and this may have contributed to degradation of habitat for the species (Rowland, 1993; NSW Fisheries, 2004). This conclusion is supported by observations from the late-1930s that siltation in the upper Clarence River, following the removal of timber from the granite slopes of the catchment area, led to the the loss of deep pools (SMH, 1937). Releases of contaminated water from tailings dams at gold and tin mines caused the death of this species, and other freshwater fish, in part of the Clarence River system (F. Winters, pers. comm., cited in Rowland, 1993). Many complaints were made between the late-1930s and the late-1940s by fishers and farmers about pollution in the upper Clarence, Mann, Nymboida and Rocky rivers, allegedly from the slurry of tin mining operations, affecting water quality and clarity, with observations of a number