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

Conservation Status

Maccullochella ikei () 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 Protection Act 1992 (Cwlth).

The species is also listed as Endangered under the Fisheries Management Act 1994 () 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 cod, eastern cod, codfish, or cod (Harris and Rowland, 1996), is a large freshwater 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).

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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 , 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 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, , , aquatic birds and some terrestrial prey, including snakes (Rowland, 1996).

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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 of fish kills through these river systems (Daily Examiner, 1935; Courier Mail, 1937; Daily Examiner, 1937; Daily Examiner, 1938; Northern Star, 1938; SMH, 1938; Daily Examiner, 1947).

The current threats to eastern freshwater cod include habitat degradation, and its associated impacts of sedimentation, large woody removal, changes to natural river flows, barriers to fish migration, removal of riparian vegetation and water pollution (Rowland, 1996; NSW Fisheries, 2004).

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There are indications that illegal fishing of the eastern freshwater cod is still occurring and therefore is a known threat, with tags from radio tagged fish being found amongst fish remains at some distance from the waterways in 2005 (Butler, 2009). It is suspected that a range of fishing methods are used to catch the species, including lines, explosives and gill nets (NSW Fisheries, 2004). It is widely known amongst fishers that eastern freshwater cod are a totally protected species, and that deliberately fishing for them is illegal (NSW Fisheries, 2004). Eastern freshwater cod are however regularly caught and released by fishers who target the species or are targeting other species such as ( novemaculeata) and freshwater catfish (Tandanus tandanus) (NSW Fisheries, 2004).

Another potential threat to the eastern freshwater cod is the introduction of species non-native to the area. There are reports that the closely related (M. peelii), which did not naturally occurring east of the , has been stocked into dams in the Richmond and Clarence river catchments (Wager and Jackson, 1993; NSW Fisheries, 2004). An Australian, mainly tropical species, the banded grunter (Amniataba percoides) has been introduced to the Clarence River catchment and could pose a threat to eastern freshwater cod given its ability to breed and recruit in very large numbers, drawing comparisons to the competition and predation impacts of redfin (Perca fluviatilis), which is found in other parts of (NSW Fisheries, 2004). Other species such as gambusia (Gambusia holbrooki) and goldfish (Carassius auratus) that have been introduced to the system, but it is unclear whether these species pose any risk to the eastern freshwater cod (NSW Fisheries, 2004).

Stocking hatchery-bred juveniles back into the eastern freshwater cod’s former historical range, potentially threatens the species by reducing the genetic diversity of the naturally-occurring wild individuals that exist in the system. Surveys between 2000 and 2007 found only small numbers, or an absence, of eastern freshwater cod at sites that were extirpated prior to the stocking of hatchery-bred juveniles into these areas (Nock et al., 2011). These same surveys identified four genetically differentiated populations in the Clarence system (mainly within the Mann-Nymboda rivers catchment) which suggested that these populations are fragmented and that there is restricted dispersal of individuals between the locations of these populations, especially upstream (Nock et al., 2011). Radio-tracking of the species in the Mann-Nymboida rivers catchment found that the species’ movement is relatively limited, in comparison to other Maccullochella species, which is probably a result of the complexity of the river system that has natural barriers such as rapids and waterfalls restricting movement in periods of low and high flow (Butler, 2009). When fragmentation produces a metapopulation structure in a previously continuous distributed species, genetic variation is expected to be lost first in isolated local populations and later at a species level (Gilpin, 1991). Additionally, the large amount of stocking of the species from the late-1980s until the early-2000s may have contributed to the observed genetic decline in individuals from the Mann-Nymboida rivers catchment, which includes fish derived from the largest remnant population in either the Clarence or Richmond rivers (Nock et al., 2011). Translocation of small numbers of mature individuals to areas low in genetic diversity, can effect a ‘genetic rescue’ restoring genetic diversity and fitness though hybrid vigour (Tallmon et al., 2004). Nock et al. (2011) raises the prospect of translocating eastern freshwater cod individuals to upstream sites, such as from lower in the Mann-Nymboida rivers catchment to areas more upstream in the catchment, such as the Guy Fawkes and Sara rivers.

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Conservation Actions

Conservation and management actions

• Implement a strategic in-stream habitat protection and restoration plan.

• Review fishing closures and management practices in the Mann-Nymboida rivers catchment (part of the Clarence River catchment) including consideration of extending closures beyond the breeding season of the eastern freshwater cod until the population can be demonstrated to have recovered.

• Implement a management plan for fish species not native to the range of the eastern freshwater cod that may be affecting eastern freshwater cod survival, including banded grunter (Amniataba percoides) and Murray cod (M. peelii).

• Implement a strategic approach to protecting riparian vegetation throughout the Richmond and Clarence river catchments.

• Maximise compliance with fishing regulations related to the species.

Survey and monitoring priorities

• Monitor the impact of fishing activities, targeted and non-targeted, in the Mann-Nymboida rivers catchment (part of the Clarence River catchment) on the wild population of eastern freshwater cod.

• Undertake surveys to collect information as to the success and stability of stocked populations outside the Mann-Nymboida rivers catchment.

• Undertake surveys to determine and monitor the effective population size of individuals in the Mann-Nymboida rivers catchment, and any other area discovered that supports the species .

Information and research priorities

• Investigate factors limiting stocked populations from becoming new, self-sustaining populations in the Richmond and Clarence river catchments, outside the Mann-Nymboida rivers area.

• Investigate the suitability of undertaking genetic translocations to upstream sites to improve genetic diversity and fitness of fragmented populations.

• Assess the effectiveness of various fish passage structures so that the most appropriate may be installed at relevant barriers to fish movement in the Richmond and Clarence river catchments.

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References cited in the advice

Allen GR, Midgley SH and Allen M (2002). Field Guide to the Freshwater of Australia. Western Australian Museum, Perth.

Butler GL (2009). Biology and conservation of the endangered eastern freshwater cod Maccullochella ikei Rowland. PhD thesis, Southern Cross University, Lismore, New South Wales.

Butler GL and Rowland SJ (2008). Using traditional age and growth techniques in endangered species management: eastern freshwater cod, Maccullochella ikei. Marine and Freshwater Research, vol. 59: 684 – 693.

Butler GL and Rowland SJ (2009). Using underwater cameras to describe the reproductive behaviour of the endangered eastern freshwater cod Maccullochella ikei. Ecology of Freshwater Fish, vol. 18: 337 – 349.

Courier Mail (1937). Fish Killed in the Clarence – Pollution By Mines Alleged. The Courier Mail Newspaper, Brisbane, , Monday 11 October 1937, p. 12. Viewed: 9 July 2015. Available on the Internet at: http://trove.nla.gov.au/

Daily Examiner (1935). Alleged Pollution of the Clarence. The Daily Examiner Newspaper, Grafton, New South Wales, Wednesday 30 October 1935, p. 4. Viewed: 9 July 2015. Available on the Internet at: http://trove.nla.gov.au/

Daily Examiner (1937). Polluting the Waters of the Clarence. The Daily Examiner Newspaper, Grafton, New South Wales, Wednesday 6 October 1937, p. 4. Viewed: 9 July 2015. Available on the Internet at: http://trove.nla.gov.au/

Daily Examiner (1938). River Pollution – Fisherman Protesting. The Daily Examiner Newspaper, Grafton, New South Wales, Saturday 2 April 1938, p. 2. Viewed: 9 July 2015. Available on the Internet at: http://trove.nla.gov.au/

Daily Examiner (1939). Dynamiters blamed – Fish Destroyed At Gorge – Proposed Petition to Chief Secretary. The Daily Examiner Newspaper, Grafton, New South Wales, Tuesday 24 January 1939, p. 4. Viewed: 9 July 2015. Available on the Internet at: http://trove.nla.gov.au/

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Daily Examiner (1947). Letters to the Editor – River Pollution. Letters to the Editor from Howard, CA, Grafton, 10 September 1947. Published in the Daily Examiner Newspaper, Grafton, New South Wales, Friday 12 September 1947, p. 2. Viewed: 9 July 2015. Available on the Internet at: http://trove.nla.gov.au/

Faragher RA, Brown P and Harris JH (1993). Population surveys of the endangered fish species (Maccullochella macquariensis) and eastern cod (M. ikei). New South Wales Fisheries Research Institute, Cronulla, New South Wales, pp. 22.

Farmer and Settler (1936). Bushfires Rage in Northern Districts – Family’s Narrow Escape After Home Was Wiped Out – Crops and Pastures Destroyed. The Farmer and Settler Newspaper, Sydney, New South Wales, Thursday 29 October 1936, p. 2. Viewed: 9 July 2015. Available on the Internet at: http://trove.nla.gov.au/

Gilpin M (1991). The genetic effective size of a metapopulation. Biological Journal of the Linnean Society, vol. 42: 165 – 175.

Harris JH and Rowland SJ (1996). Australian freshwater and basses. In: McDowall R (ed.) (1996). Freshwater fishes of South-Eastern Australia. Reed Books, Chatswood, pp. 150 – 163.

Merrick JR and Schmida GE (1984). Australian freshwater fishes: biology and management. Griffin Press Limited, Netley, South Australia.

National Advocate (1936). Bush Fires – Outbreak Near Grafton. The National Advocate Newspaper, Bathurst, New South Wales, Friday 4 December 1936, p. 2. Viewed: 9 July 2015. Available on the Internet at: http://trove.nla.gov.au/

New South Wales Fisheries (NSW Fisheries) (2004). Eastern (Freshwater) Cod (Maccullochella ikei) Recovery Plan. New South Wales Fisheries, Port Stephens Fisheries Centre, Nelson Bay, New South Wales.

Newcastle Morning Herald and Miners’ Advocate (NMHMA) (1936). Fires Checked – Another Anxious Day on North Coast – Many Homes Saved. The Newcastle Morning Herald and Miners’ Advocate Newspaper, New South Wales, Saturday 31 October 1936, p. 12. Viewed: 9 July 2015. Available on the Internet at: http://trove.nla.gov.au/

Northern Star (1938). Upper Arms of Clarence & Nymboida Polluted. The Northern Star Newspaper, Lismore, New South Wales, Wednesday 7 September 1938, p. 6. Viewed: 9 July 2015. Available on the Internet at: http://trove.nla.gov.au/

Nock CJ (2009). Conservation genetics of the endangered eastern freshwater cod, Maccullochella ikei. PhD thesis, Southern Cross University, Lismore, New South Wales.

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Nock CJ, Ovenden JR, Butler GL, Wooden I, Moore A and Baverstock PR (2011). Population structure, effective population size and adverse effects of stocking in the endangered Australian eastern freshwater cod Maccullochella ikei. Journal of Fish Biology, vol. 78: 303 – 321.

Pollard DA and Wooden I (2002). Interim results of surveys in the Clarence and Richmond River systems: supplement to eastern freshwater cod (Maccullochella ikei) recovery plan. New South Wales Fisheries, Nelson Bay, pp. 21.

Pollard D, Wooden I and Morris S (2002). Supplement to Eastern cod Recovery Plan: Interim results of surveys in the Clarence and Richmond River systems. New South Wales Fisheries Centre, Cronulla, pp. 1 – 21.

Rowland SJ (1989). Conservation of the eastern freshwater cod. In: Mears PT, Hennessy DW and Rowland SJ (eds.) (1989). Grafton agricultural research and advisory station research report 1987–8. New South Wales Agriculture and Fisheries, Grafton, New South Wales, pp. 8 – 9.

Rowland SJ (1993). Maccullochella ikei, an Endangered Species of Freshwater Cod (Pisces: Percichthyidae) from the Clarence River System, NSW and M. peelii mariensis, a New Subspecies from the Mary River System, Qld. Records of the Australian Museum, vol. 45: 121 – 145.

Rowland SJ (1996). Threatened fishes of the world: Maccullochella ikei Rowland, 1985 (Percichthyidae). Environmental Biology of Fishes, vol. 46: 350.

Sydney Morning Herald (SMH) (1936a). Bushfires – Havoc in Upper Clarence – Women Firefighters – Dramatic Battles With Flames. The Sydney Morning Herald Newspaper, New South Wales, Wednesday 28 October 1936, p. 15. Viewed: 9 July 2015. Available on the Internet at: http://trove.nla.gov.au/

Sydney Morning Herald (SMH) (1936b). Bushfires – Hundreds Fight Flames – Family’s Danger – Farmer’s Death After Ordeal. The Sydney Morning Herald Newspaper, New South Wales, Thursday 29 October 1936, p. 11. Viewed: 9 July 2015. Available on the Internet at: http://trove.nla.gov.au/

Sydney Morning Herald (SMH) (1936c). Bushfires – Practically Under Control – Volunteers Save Homes. The Sydney Morning Herald Newspaper, New South Wales, Saturday 31 October 1936, p. 18. Viewed: 9 July 2015. Available on the Internet at: http://trove.nla.gov.au/

Sydney Morning Herald (SMH) (1936d). Bushfires – Township Saved – Dash Through Blazing Scrub. The Sydney Morning Herald Newspaper, New South Wales, Saturday 5 December 1936, p. 18. Viewed: 9 July 2015. Available on the Internet at: http://trove.nla.gov.au/

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Sydney Morning Herald (SMH) (1937). Clarence River Pollution – To the Editor of the Herald. Letters to the Editor from Archibald, JW, Dulwich Hill, 11 October 1937. Published in the Sydney Morning Herald Newspaper, New South Wales, Tuesday 12 October 1937, p. 8. Viewed: 9 July 2015. Available on the Internet at: http://trove.nla.gov.au/

Sydney Morning Herald (SMH) (1938). River Pollution Alarms Fisherman. The Sydney Morning Herald Newspaper, New South Wales, Saturday 10 September 1938, p. 6. Viewed: 9 July 2015. Available on the Internet at: http://trove.nla.gov.au/

Tallmon DA, Luikart G and Waples RS (2004). The alluring simplicity and complex reality of genetic rescue. Trends in Ecology & Evolution, vol. 19: 489 – 495.

Uralla Times (1936). Rescues Made From Bushfires. The Uralla Times Newspaper, New South Wales, Thursday 5 November 1936, p. 5.

Wager R (1996). Maccullochella ikei. In: IUCN (International Union for Conservation of Nature) (2015). IUCN Red List of Threatened Species. Version 2015.1. Viewed: 18 June 2015. Available on the Internet at: www.iucnredlist.org

Wager R and Jackson P (1993). The Action Plan for Australian Freshwater Fishes. Canberra, Australian Nature Conservation Agency, Australian Capital Territory.

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