|Scientific Name:||Heterodontus galeatus|
|Species Authority:||(Günther, 1870)|
|Red List Category & Criteria:||Least Concern ver 3.1|
|Assessor(s):||Kyne, P.M. & Bennett, M.B. (SSG Australia & Oceania Regional Workshop, March 2003)|
|Reviewer(s):||Fowler, S. & Cavanagh, R.D. (Shark Red List Authority)|
An uncommon heterodontid shark restricted to relatively shallow water (0 to 93 m) and endemic to the eastern Australian states of Queensland and New South Wales. It is considered rare, particularly when compared with the sympatric Heterodontus portusjacksoni. Little information is available on its life history. The species is not targeted commercially, and incidental capture, recreational fishing and protective beach meshing programs are not significantly impacting. Post-capture survivorship appears high. Although rare there are no current threats to the species. However, given this apparent rarity, further research and close monitoring of catches is necessary.
|Range Description:||Heterodontus galeatus is endemic to the western Pacific Ocean in warm temperate waters along the east coast of Australia ranging from Cape Moreton in southern Queensland south to Batemans Bay in New South Wales (Last and Stevens 1994, Johnson 1999). Whitley (1940) reports an egg case from Moa Island in the Torres Strait, but this northern Queensland record may be doubtful (J. Johnson pers. comm).|
Native:Australia (New South Wales, Queensland)
|FAO Marine Fishing Areas:||
Pacific – southwest; Pacific – western central
|Range Map:||Click here to open the map viewer and explore range.|
|Population:||No information available on populations.|
|Current Population Trend:||Unknown|
|Habitat and Ecology:||
Heterodontus galeatus is considered to be less common than the sympatric Port Jackson shark, Heterodontus portusjacksoni, which is found throughout most of the range of H. galeatus. However, H. galeatus tends to replace H. portusjacksoni in northern New South Wales (NSW) and southern Queensland with the centre of its distribution in warmer waters than H. portusjacksoni (Whitley 1940, McLaughlin 1969). McLaughlin (1969) when assessing the heterodontid sharks of the central NSW coast wrote that H. galeatus is "difficult to find underwater and was rarely encountered by fishermen, indicting that its local density was probably much lower than that of H. portusjacksoni" (McLaughlin 1969, page 9). This species is recorded from the intertidal zone to 93 m on the continental shelf (Whitley 1940, Michael 1993, Last and Stevens 1994). Its bathymetric distribution is largely unknown but some speculate that it may be more common in deeper waters than close inshore (Kuiter 1993, Jeff Johnson, personal communication). The species is found around rocky reefs, among large macroalgae and on seagrass beds (Michael 1993). Heterodontus galeatus does not appear to form large aggregations as displayed by H. portusjacksoni. Individuals of both H. galeatus and H. portusjacksoni can be observed together occupying the same habitat (David Powter, pers. comm.).
This species is nocturnal and feeds on a variety of benthic and epibenthic prey including echinoids (largest component of diet), crustaceans, molluscs and small fish (Last and Stevens 1994). McLaughlin (1969) examined the gut contents of four mature animals of which the bulk of contents consisted of the echinoids, Centrostephanus rodgersii and Heliocardis erythrogramma. This diet appears similar to that of H. portusjacksoni, however, McLaughlin (1969) suggests that H. galeatus may display greater specialisation on the two echinoid species. These sharks are known to extend their heads between rocks in search of prey items (Michael 1993). Heterodontus galeatus has been observed feeding on a H. portusjacksoni egg case (David Powter, pers. comm.).
Various maximum sizes of H. galeatus have been reported. Stead (1963, page 19) states that "as a general rule it [H. galeatus] is found of a somewhat smaller size than the common Port Jackson shark [H. portusjacksoni] of similar age". Heterodontus portusjacksoni is reported to grow to a maximum of 165 cm total length (TL) but is "normally much smaller" (Last and Stevens 1994, page 113). Whitley (1940) reported a total length (TL) of 120 cm for H. galeatus. Last and Stevens (1994) report the species attaining 130 cm TL. The Fishbase database provides a larger maximum size of 152 cm TL (Froese and Pauly 2002), Michael (1993) reports 150 cm TL and observations on the NSW central coast suggest a maximum size of at least 150 cm TL (David Powter, pers. comm).
Last and Stevens (1994) report that females mature at 70 cm TL and males at 60 cm TL. However, there have been recent observations of two males from southern Queensland of 53.5 and 56 cm TL, which were sexually mature, based on the state of their secondary sexual organs following the assessment of maturity as outlined by Bass et al. (1974) (unpublished data). The reported size of maturity for females may be based on a single captive individual hatched and held at the Taronga Park Aquarium, Sydney, Australia (Whitley 1950). This individual is reported to have matured in its eleventh year of age, based on the first time it laid eggs in captivity (Whitley 1950). Females lay spiral-shaped egg cases (about 11 cm long) that have long tendrils at their apices (tendrils reported up to 2 m in length), providing attachment to seaweed or sponges (Waite 1896, Michael 1993, Last and Stevens 1994). Oviposition is reported to take place during July and August in depths of 20 to 30 m (McLaughlin 1969, Last and Stevens 1994). Michael (1993) reports egg-laying in depths of 15 m or more, also during late winter, but states that oviposition can occur all year around. There are also reports of egg cases attached to sponges in waters as shallow as 8.6 m (David Powter, pers. comm.). Heterodontus galeatus generally lays in deeper water than H. portusjacksoni, which mostly lays in less than 5 m (McLaughlin and O’Gower 1971). Young are reported to hatch at about 22 cm TL (Last and Stevens 1994). The individual hatched in captivity at the Taronga Park Aquarium was reported at a smaller size of about 17 cm TL (Jacups 1943, Whitley 1950).
There are minimal reports on the egg-laying rate and hence annual fecundity of the species. McLaughlin (1969) examined one mature female (77.5 cm TL) in June, and found it to be consistent with an estimated fecundity for H. portusjacksoni of 10-16 eggs per year. Reproductive periodicity has not been documented, however, given that concentrations of eggs are reported seasonally during late winter, it is suggested that the species breeds annually. Furthermore, H. portusjacksoni displays an annual reproductive cycle (McLaughlin and O’Gower 1971) implying that H. galeatus may be similar. Whitley (1940) suggested a gestation period of at least five months while others (Jacups 1943; Whitley 1950; Last and Stevens 1994) report a longer period of 8-9 months. This latter figure may be based on the one captive individual held at the Taronga Park Aquarium. There is no information available on age and growth in wild H. galeatus; however, limited information is available from captivity. Jacups (1943) and Whitley (1950) report a growth rate of 5 cm per year for the captive Taronga Park female. It is thought that the species is relatively long-lived given its apparent protracted immaturity (Whitley 1950).
This species is not targeted or marketed commercially (Last and Stevens 1994, Nick Otway, personal communication). Recreational fishing is thought to have little impact on the species because of its apparent rarity in inshore waters. Spearfishers are more likely to encounter H. portusjacksoni on inshore reefs, and they are known to take this species for sport. Line fishers may encounter H. galeatus on rare occasions. The species is caught as bycatch in various commercial fisheries operating in NSW and southern Queensland waters. The species is taken as bycatch in demersal prawn trawl fisheries in NSW (Ocean Prawn Trawl Fishery) and in Queensland (eastern king prawn sector of the East Coast Trawl Fishery). The NSW ocean trap and line fishery is also likely to capture this species, however numbers taken as bycatch are not known as there is no distinction in the recording of the two species of heterodontid in fisheries statistics (H. galeatus and H. portusjacksoni) (Nick Otway, pers. comm). Heterodontus spp. captured as bycatch in this fishery are normally released alive (Nick Otway, pers. comm.).
Protective beach meshing programs operate in NSW and Queensland waters and are likely to capture H. galeatus. Numbers caught in Queensland are not available while catches in the NSW Protective Beach Meshing Program are not divisional between the two heterodontid species (Nick Otway, pers. comm). Between October 1972 and December 1990, 435 Port Jackson sharks were caught in this program, equating to a catch rate of 0.394 sharks/km of net/year (Krogh 1994) (these figures are considered as underestimates). Krogh (1994) notes that H. portusjacksoni, being the more common species, is more likely to constitute the larger portion of the catch. Reid and Krogh (1992) provide information on net mortality for Heterodontus spp. caught in the program. Of 60 individuals sampled, 96.7% were alive in the net, the highest survival rate of the 11 species or species groups sampled. Non-dangerous sharks are released by contractors servicing the protective nets whenever practical (Reid and Krogh 1992). Given this survivorship, and if animals are successfully released alive, then beach meshing may not be having a significant impact on Heterodontus spp. Similarly, if animals are successfully released alive from prawn trawlers, then these activities may also be having minimal impact. However, information on post-release mortality is unavailable and therefore catches need to be classified to species level and catch rates monitored.
Heterodontus galeatus is listed as a Declared Animal in Schedule 3 of the Queensland Marine Parks (Moreton Bay) Zoning Plan 1997. This schedule declares species that could be affected by over-exploitation. This declaration limits the collecting of H. galeatus in the Moreton Bay Marine Park, a Marine Protected Area (MPA) of approximately 306,000 hectares. However, records of the species inside Moreton Bay, and therefore in the majority of the area of the MPA, are rare (Johnson 1999), the species usually occurring in offshore regions. Under Schedule 3, collection of H. galeatus requires a permit.
The species is also likely to occur in a number of MPAs in NSW waters, however recreational line and spear fishing are permitted in many of these. Marine Protected Areas in NSW waters where H. galeatus is likely to occur and where commercial and recreational fishing activities are completely banned in at least some sections of the park are: Solitary Islands Marine Park (71,000 hectares), Jervis Bay Marine Park (21,450 hectares), Cabbage Tree Bay Aquatic Reserve (Sydney, 17 hectares), Bushrangers Bay Aquatic Reserve (Shell Harbour, three hectares) and Shiprock Aquatic Reserve (Port Hacking, two hectares). Zoning plans for these parks are complex and ‘no-take’ zones only exist in small areas. There is also a proposal for a Marine Park in the Byron Bay region, northern NSW. Additionally, H. galeatus is likely to occur in the Commonwealth managed Solitary Islands Marine Reserve (17,000 hectares) adjacent to NSW’s Solitary Islands Marine Park.
|Citation:||Kyne, P.M. & Bennett, M.B. (SSG Australia & Oceania Regional Workshop, March 2003). 2003. Heterodontus galeatus. The IUCN Red List of Threatened Species 2003: e.T41824A10573664. . Downloaded on 05 May 2016.|
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