© Baker, J.L. (2009) Marine Species of Conservation Concern in South Australia Full citation Baker, J.L. (2009) Marine Species of Conservation Concern in South Australia: Volume 1 - Bony and Cartilaginous Fishes. Report for the South Australian Working Group for Marine Species of Conservation Concern. J. Baker (consultant); Science and Conservation Division, and Coast and Marine Conservation branches of S.A. Department for Environment and Heritage (DEH); Marine and Coastal Community Network of S.A. (MCCN), and Threatened Species Network (TSN). Web version published by Reef Watch, South Australia.

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Green Moray / Yellow Moray

Family Name:	Muraenidae
Scientific Name:	Gymnothorax prasinus (Richardson, 1848)
Recommended Status in S.A:	Data Deficient, possibly Rare E(ii) in S.A.
Rationale:  Green Moray is included here because (i) although the species is commonly recorded in south-eastern and south-western Australia, it is uncommon in South Australia, apparently with only two published records known to date; (ii) this site-associated reef fish species from shallow subtidal waters may be vulnerable to capture in rock lobster pots (as occurs in W.A.), and also, in some areas, might be susceptible to site-specific habitat impacts (such as reduction in cover of kelp and other macroalgae), but more information is required; and (iii) there is little information about relative abundance in S.A., biology and population dynamics (such as longevity, reproduction, and dispersal range). The recommended current status is Data Deficient, because surveys would be required to determine whether the species is naturally rare in S.A. (and based on irregular settlement of larvae out of the normal geographic range), or whether the infrequently of recording is due to its habit (dwelling in caves and crevices), nocturnal nature and relative inaccessibility.

Page Contents

Current Conservation Status

No listings known

Distribution

Southern Australia and New Zealand

The Green Moray is the most common moray in south-eastern Australia (Castle, in Gomon et al., 1994). The eastern population ranges from southern Queensland, through N.S.W., to eastern Victoria and northern Tasmania (Castle, in Gomon et al., 1994; Böhlke and McCosker, 2001). The species is common in the Sydney area (Australian Museum, 2004d) and in other parts of New South Wales (Kuiter, 1996a). There are numerous records of the eastern population in New South Wales and eastern Victoria (Australian Museum records, Museum of Victoria records, West Australian Museum records, cited in OZCAM database, 2005). Green Moray is found very occasionally on the east coast of Tasmania, at least as far south as Maria Island (G. Edgar, pers. comm., 2006).
A separate western population ranges from Shark Bay in W.A., southwards and eastwards to Anxious Bay in the Great Australian Bight, South Australia (Castle, in Gomon et al., 1994; West Australian Museum records, cited in OZCAM database, 2005). The Green Moray is considered common along parts of the Western Australian coast, but is found infrequently along the south coast of Australia (Hutchins and Swainston, 1986).
The species has also been recorded in New Zealand (where yellow individuals occur) (Castle, in Gomon et al., 1994), on the North Island (Francis, 1996; Brook, 2002).

South Australia

The first record of this species in South Australia (and one of only two records in the S.A. Museum) was a specimen captured in a rock lobster pot on the exposed coast of Cape Radstock, near Streaky Bay, in the eastern Great Australian Bight, during period December 1979 - February 1980 (Glover and Branden, 1983; South Australian Museum record F 04642, cited in OZCAM database, 2006). The Cape Radstock record has been listed as extra-limital (i.e. outside of the known range) (Hutchins, 1994, cited by Böhlke and McCosker, 2001) (but see below).
The second record known from S.A. was a specimen taken off Althorpe I. (Investigator Strait) in 1987, caught in a bait trap at 37m deep, baited with octopus and rock lobster (South Australian Museum record 06704, cited by R. Foster, SAM, pers. comm., 2006).

Habitat

The Green Moray is found in the shallow subtidal, in the vicinity of rocky reef areas with a cover of kelp or other macroalgae (Castle, in Gomon et al., 1994; Australian Museum 2002m; Australian Museum, 2004d). Morays occur in such rocky reef habitat, in bays, estuaries, and also in deeper offshore waters (Australian Museum, 2004d).
The Green Moray mainly inhabits holes and crevices in reef (Russell, 1983, cited by Froese and Pauly, 2008), and is also found in caves and under ledges (Hutchins and Swainston, 1986), and under objects on the sea bottom, such as pipes (Australian Museum, 2004d).
In eastern Australia, the species has also been recorded in shallow rock pools off rocky headlands (Silberschneider and Booth, 2001; Griffiths, 2003a, 2003b), and Green Morays are considered to be truly resident (rather than transient) in such habitat (Silberschneider and Booth, 2001). At one rock pool site studied in N.S.W., the number of Green Morays observed in rock pools was three times higher in spring, compared with autumn (Griffiths et al., 2004).
Kuiter (1993 and 1996a) reported the habitat of the Green Moray to be mainly coastal reefs (various rocky and kelp habitats) but also silty harbours, muddy estuaries, and clear offshore reefs in deeper waters.
Most records are known from the shallow subtidal, to about 40m deep (Böhlke and McCosker, 2001).

Notes on Biology and Behaviour

Size and Age

Reported maximum size of Green Moray is 1.55m (Castle, in Gomon et al., 1994; Australian Museum, 2004d), based on a specimen taken at Bremer Bay in southern W.A., in 1985 (Australian Anglers Association record), but specimens of that size are rarely observed.
Related species in the genus (e.g. Gymnothorax mordax) are reported to be long-lived (Eschmeyer et al., 1983).

Reproduction

Morays have oceanic, epipelagic larvae (Nelson, 1994; Castle, in Gomon et al., 1994).
Larvae of Green Moray settle to the bottom when they are about 4cm long (Kuiter, 1993).

Behaviour

The Green Moray is nocturnally active, and stays in holes or crevices in rocky reef or coral reef, during the day (Russell, 1983; Australian Museum, 2004d). This habit provides protection from predators and allows the Green Moray to strike at prey from a hidden position (Australian Museum, 2004d).

Diet and Feeding Behaviour

The Green Moray is carnivorous, and feeds opportunistically on small mobile prey (Russell, 1983). Examples include crabs and benthic fish (such as scorpion fish) (Russell, 1983), small cephalopods, and sea urchins, as observed by recreational divers in southern Australia.
Morays have the ability to tie their bodies in knots to gain leverage when tearing food (Australian Museum, 2004d).

Fisheries and Trade Information

General – Commercial

Green Moray G. prasinus and the Western Moray (Woodward’s Reef-eel) G. woodwardi are taken as bycatch in the Western Australian Rock Lobster fishery. Morays are “frequently caught in rock lobster pots” but are not retained, and the rate of survival of those returned to water is not known (Australian Government DEH, 2002).
There are records of the species being taken (presumably as bycatch) by commercial fishing in the Port Philip Bay / Bass Strait area (Anonymous, 2002b, cited by Froese and Pauly, 2008).
The Green Moray is not fished commercially, but has commercial value as an aquarium fish (Froese and Pauly, 2008). Green Morays are kept in zoos and aquariums in various parts of the world (e.g. U.S.A.), and are sold by a number of aquarium fish suppliers (for example, in U.S.A., Switzerland, and Russia).

General – Recreational

The species is edible (Hutchins and Swainston, 1986), but there is little information on the recreational catch. The species is not usually targeted, but there are fishers’ reports (e.g. from W.A.) of Green Moray taking a hook baited for other species. Species-specific catch statistics are not recorded (e.g. Henry and Lyle, 2003). Some clubs and associations keep records of the maximum sizes caught (e.g. Australian Anglers Association, W.A. Division, 2005).
Green Moray (= Yellow Moray, in New Zealand) is reported to be taken as bycatch by recreational fishers in some parts of N.Z (e.g. Denny et al., 2003, Table 1).

South Australia

The species has been recorded as bycatch in a rock lobster pot in S.A. (South Australian Museum record F 04642, cited in OZCAM database, 2006); however no information is available for this report on the frequency of capture of Green Moray in that fishery in South Australia. It is noted that the species was not listed as being recorded, in studies of rock lobster fishery bycatch in S.A. during the 1990s (Prescott and Xiao, 2001) or early 2000s (Brock et al., 2004).

Vulnerable Characteristics of the Species, and Threatening Processes

In South Australia, the apparent uncommonness of this species, along with its habit of dwelling in holes and crevices in rocky reefs (and thus avoiding capture), serve to reduce the threat of population decline in this species. However, because the Green Moray may be a long-lived species, and occurs in shallow subtidal reefs, any processes which have adverse impacts upon the quality of macroalgae-covered reef might affect nearshore populations of this species, in any part of the range. This might include processes such as siltation, eutrophication, and physical destruction of nearshore habitat through coastal development. Over longer time scales, ecosystem changes due to food chain disruption, and global warming might also adversely affect macroalgae cover.
Bycatch in rock lobster fisheries may be a potential threat; however the species appears to be infrequently recorded in lobster pots in South Australia. It is noted that the only two formal records of this species in S.A. (known to date) were specimens taken in traps, including one in a rock lobster pot, but the apparent low frequency of capture would reduce the threat of this practice to any Green Moray population in South Australia. In W.A., however, formal risk analysis (cited by Australian Government DEH, 2002), identified moray eels and manta rays as being the bycatch most at risk from the W.A. Rock Lobster fishery. Moray eels are usually returned alive, although their survival after release is uncertain. A submission from W.A. on the environmental assessment of that fishery suggested the current design of rock lobster pots probably allows most morays to escape, and that pots are inefficient at taking moray eels, but the submission also noted that moray eels frequently are caught in lobster pots. While the submission suggested the frequency of capture may be an indicator of high abundance of moray eels, an alternative interpretation is that it indicates that the fishing efficiency of pots at taking moray eels may be greater than estimated (Australian Government DEH, 2002). The threat of rock lobster fishing to Green Moray and Western Moray populations has not been investigated.
Other potential threats to populations across southern Australia may include recreational fishing, collection for the aquarium trade; and harassment by divers.

Research and Management Requirements

Although the Green Moray is regularly recorded in south-eastern and south-western Australia, it appears to be uncommon in South Australia and has rarely been recorded here. Fishers and divers in South Australia should record the presence and location of Green Moray when it is found, and dead specimens in fisheries bycatch (e.g. rock lobster pots) should be sent to the South Australian Museum or the Australian Museum.
The incidence of capture of Green Moray in rock lobster pots in S.A. is not known; however the species is caught regularly in rock lobster pots in W.A., and measures to reduce bycatch (such as pot design) should be investigated.
In other States, any capture (legal or illegal) of this species for the aquarium market should be monitored.

Other Information

The Green Moray occurs in a number of marine parks and reserves in other parts of the range, including Booderee National Park (Australian Government DEH, 2006b); Julian Rocks (Cape Byron Marine Park) in New South Wales; Cape Howe and Point Hicks in Victoria (Edmunds et al., 2005); islands in the Houtman Abrolhos in W.A. (Watson et al., 2005), and the Poor Knights Islands Marine Reserve (Denny et al., 2003) and Mimiwhangata Marine Park in New Zealand (Denny and Babcock, 2004). It is noted that in N.Z., there is some evidence that populations of the Green Moray respond positively to the protection offered by no-take marine reserves (e.g. Shears and Usmar, 2006).
In a re-examination of type specimens of Gymnothorax species in Australia and New Zealand, Böhlke and McCosker (2001) suggested that G. maculaepinnis Bleeker, 1866 and Gymnothorax leecote Scott, 1965 (from Tasmania) should be assigned to Gymnothorax prasinus (Richardson, 1848).
The Green Moray is one of the fish species monitored in Victoria by Reef Watch, a community-based reef monitoring program.