|Scientific Name:||Heterodontus portusjacksoni (Meyer, 1793)|
|Red List Category & Criteria:||Least Concern ver 3.1|
|Assessor(s):||Huveneers, C. & Simpfendorfer, C.|
|Reviewer(s):||Walls, R.H.L. & Kyne, P.M.|
|Facilitator/Compiler(s):||Kyne, P.M., Walls, R.H.L., Simpfendorfer, C. & Chin, A.|
The Port Jackson Shark (Heterodontus portusjacksoni) is a medium-sized (to 165 cm total length), abundant shark endemic to Australian waters, with one vagrant recorded in New Zealand. Although the Port Jackson Shark is a large bycatch component of several fisheries across its range, most individuals are returned to the water alive and post-release stress studies have shown that the species is very resilient to capture stress from gillnet, trawl, and longline gear, suggesting high post-release survival rates. The estimated decline of the Port Jackson Shark in Bass Strait between 1973-74 and 1998-2001 has now ceased and has been reversed as fishers no longer persecute the species. This decline was only observed in a small proportion of the species' range and standardized catch-per-unit-effort from an observer program does not support the decline observed in the shark abundance surveys. In addition, a rapid semi-quantitative ecological risk assessment method showed that the Port Jackson Shark is at low risk from several fisheries because of its low catch susceptibility. The effects of fisheries on the Port Jackson Shark in other parts of its distribution are likely to be negligible and habitat modification and other environmental factors do not appear to be a threat to the health of the population. There is currently no evidence to suggest that the Port Jackson Shark faces any risk of extinction, justifying a listing of Least Concern.
|Previously published Red List assessments:|
|Range Description:||The Port Jackson Shark is a common inhabitant of the Australian continental shelf south of 30°S from Byron Bay (New South Wales) to the Houtman Abrolhos (Western Australia), including Tasmania. Records from York Sound (northern Western Australia) and Moreton Bay (Queensland) are questionable. The only record from New Zealand comes from one individual (Last and Stevens 2009).|
Native:Australia (New South Wales, South Australia, Tasmania, Victoria, Western Australia)
|FAO Marine Fishing Areas:|
Indian Ocean – eastern; Pacific – southwest; Pacific – western central
|Range Map:||Click here to open the map viewer and explore range.|
A well-known and abundant temperate species, with no evidence of population decline in most of its range.
Surveys of shark population abundance caught as part of the Gillnet, Hook and Trap Sector (GHAT) (part of the Southern and Eastern Scalefish and Shark Fishery, SESSF) indicate that the number of Port Jackson Sharks in Bass Strait declined from 701 individuals caught per 1,000 km lift hours (standard error; s.e. = 180) in 1973-76 to 169 (s.e. = 40) in 1998-2001 (Braccini et al. 2009). The most recent survey performed in 2007-08 reported 204 individuals per 1,000 km lift hours (s.e. = 75) and suggest that the decline has now ceased (Braccini et al. 2009). Overall, this represents an estimated population decline of 70.9% in 36 years. However, standardised catch per unit effort from the Integrated Scientific Monitoring Program (ISMP) data of the Great Australian Bight and Commonwealth Trawl Sectors between 1994 and 2006 does not show any declining trends (Walker and Gason 2007). This is supported by a rapid semi-quantitative ecological risk assessment method indicating that the Port Jackson Shark is at low risk to all fishing methods in far-eastern Victoria because of its low catch susceptibility (Tovar-Avila et al. 2010).
Differences in growth curves have been documented between the Port Jackson Shark from the two biogeographic zones suggested by O'Gower and Nash (1978). However, length ranges and size at maturity overlapped between bioregions, not supporting the presence of subpopulations across the distribution of the Port Jackson Shark (Izzo and Rodda 2012). Recent tracking data, however, suggests high site fidelity, with only ~15% of individuals migrating (C. Brown and N. Bass, pers. comm., February 2015). Genetics analyses are currently underway to assess the population structure of Port Jackson Sharks (C. Brown and N. Bass, pers. comm., February 2015).
|Current Population Trend:||Stable|
|Habitat and Ecology:|
The Port Jackson Shark is an abundant inhabitant of coastal reefs throughout its range, mainly on the continental shelf from close inshore to depths of 275 m (Last and Stevens 2009). It is most active at night when feeding. McGaughlin and O'Gower (1971) gave a detailed description of the habitat use and movements of the Port Jackson Shark in the waters off New South Wales. Since then, several PhD theses investigated various aspects of the species' ecology and biology (Rodda 2000, Tovar-Avila 2006, Powter 2007, Ramos 2007, Bass 2012). Powter (2007) described the Port Jackson Shark as using mostly shallow (3.5-13.5 m deep) coastal rocky reefs dominated by areas of barren and kelp habitat with adjacent sand flats.
Conventional tagging showed that the Port Jackson Shark is capable of large-scale movements between central New South Wales and Tasmania (O'Gower 1995), with individuals having been recorded up to 850 km from the reproductive areas. It is suggested that the species migrates south at the end of the breeding season to spend the summer and autumn in the deeper waters of the Bass Strait (O'Gower and Nash 1978). Its northward movement is believed to occur in deeper offshore waters because it is rarely caught on longline in water less than 60 m deep and closer than 25 km from shore before August/September (Powter 2007). However, McLaughlin (1969) conceded that the species' movements constituted a complex pattern that was not solely a movement from, and return to, specific breeding sites. This is supported by a recent acoustic tracking study showing that only ~15% of tagged individuals migrated south after breeding (C. Brown and N. Bass, pers. comm., February 2015). The lack of detections on any of the extensive Australian acoustic network receivers from the rest of the tagged animals suggest that the species might travel offshore where no receivers have been deployed. During the breeding season, the Port Jackson Shark exhibits a high level of site fidelity, with males and females spending about 90 and 85% of their time, respectively, on a single breeding reef and coming back to the same sites year after year (C. Brown and N. Bass, pers. comm., February 2015). A high level of site fidelity was also observed in Spencer Gulf (Rodda 2007). Juveniles hatch in nearshore reef areas and normally remain there until they near maturity.
This species attains approximately 165 cm total length (TL). Strong sexual dimorphism occurs with males maturing at a smaller size than females across the species' range (Powter and Gladstone 2008, Izzo and Rodda 2012). In addition, size at maturity differs between regions. The largest sexual dimorphism in the species occur in Western Australia, where males mature at 58-65 cm TL and females at 80-90 cm TL. In South Australia, males mature at 55-57.5 and females at 65-75 cm TL. In Victoria, males mature at 67.5-82 and females at 85-99 cm TL, and in New South Wales, males mature at 60-77 and females at 90-91 cm TL (Izzo and Rodda 2012). Size at birth also varies between regions from 18-21 cm TL in Western Australia up to 29.5-31.5 cm TL in Victoria. Females produce 10-16 eggs each year, with a mean ovarian fecundity of 16 (Powter and Gladstone 2008). Fecundity does not increase with TL (Powter and Gladstone 2008). The Port Jackson Shark has a synchronous annual breeding season throughout its range. Oviposition occur in fissures and caves of shallow rocky reefs during the Austral winter to spring, peaking in August-October, with hatching occurring 10-11 months later (Powter and Gladstone 2008, Rodda and Seymour 2008).
Similar to size at maturity, growth curves and ensuing age at maturity varies between sexes and regions (Izzo and Rodda 2012). In South Australia, males mature at about 6 and females at about 7-8 years old. In Victoria and New South Wales, males mature at about 7-12 and females at 12-17 years old (Powter 2007, Tovar-Avila et al. 2009, Izzo and Rodda 2012).
|Use and Trade:||Small individuals are captured for use in the hobbyist aquarium trade and fetch good prices. Live animals are sold both domestically and internationally. Port Jackson Sharks advertised by aquarium suppliers in the United States sell for up to US$180. Specimens are also collected by commercial aquaria for display purposes, but in relatively small numbers.|
The Port Jackson Shark is caught as bycatch by a range of fisheries throughout its distribution, sometimes in high numbers. Their flesh and fins are considered of poor quality across their distribution. The Port Jackson Shark is therefore rarely used commercially, resulting in most specimens being discarded in all fisheries catching them (Walker et al. 2005, Walker and Gason 2007, Ryan et al. 2013), often alive. Catch figures are mostly unavailable as fishers do not land this species.
In New South Wales, the Port Jackson Shark is caught as bycatch in the prawn trawl fishery mainly off the central coast north of Sydney, but no catch information is recorded (D. Powter, pers. comm., February 2015).
This species is caught as bycatch in the Gillnet, Hook and Trap Sector (GHAT) of the Southern and Eastern Scalefish and Shark Fishery (SESSF). As it is not retained, information about catches is only available from fisheries-dependent or -independent surveys of shark populations (e.g., Braccini et al. 2009). The likelihood of capture is affected by mesh selectivity, with the Port Jackson Shark being less susceptible to gillnet mesh sizes of six inches and lower (Walker et al. 2005). The probability of being caught in the GHAT has decreased as 7- and 8-inch gillnets were phased out in the early 1980s. More recently, the use of 6.5 inch gillnets in the GHAT is also declining as the region mostly using this gillnet size (i.e., South Australia) is frequently affected by temporary spatial closure implemented to reduce bycatch of the Australian Sea Lion. Catches of the Port Jackson Shark within the GHAT are therefore likely to have reduced compared to the 1970s. Although 100% of the Port Jackson Shark catches are reportedly discarded (Walker et al. 2005, Walker and Gason 2007), fishers were known to persecute the species resulting in poor post-release survival rate. This practice is believe to have ceased (T. Walker, pers. comm., February 2015).
In South Australia, the Port Jackson Shark is caught as bycatch in the Spencer Gulf and Gulf St Vincent Prawn Trawl Fishery (Currie et al. 2009, SARDI unpublished data) and was caught in 73 of the 120 sites sampled during a bycatch survey of the Spencer Gulf Prawn Trawl Fishery (Currie et al. 2009).
In Western Australia, the Port Jackson Shark is the major non-retained bycatch of the Temperate Demersal Gillnet and Demersal Longline Fishery (TDGDLF) and the Abrolhos Islands and Mid West Trawl Fishery (Fletcher and Santoro 2013), in which the species accounted for 75% (by estimated weight) of all observed elasmobranch discards during the late 1990s, and accounted for 10.3% of the total elasmobranch catch (McAuley and Simpfendorfer 2003, Bensley et al. 2010). A survey of commercial catches from trawl, gillnet, and longline fisheries showed that the Port Jackson Shark was one of the four most abundant bycatch elasmobranch species (Jones et al. 2010). Specifically, it was the fifth, second, and fifth most frequently caught elasmobranch, representing 7.5, 19.9, and 5.4% of the elasmobranch catches in the trawl, gillnet, and longline fishery, respectively. The size composition of the catch varied across fishing gear, with the trawl fishery catching smaller individuals (mostly 20-40 cm TL) than the gillnet (mostly 50-110 cm TL) or the longline (mostly 55-100 cm TL) fisheries. Observations on catches of demersal gillnet fishers in southern Western Australia have indicated that stocks remain relatively healthy, with large catches regularly made after 20 years of intensive fishing (C. Simpfendorfer, pers. comm., February 2015).
Although the Port Jackson Shark is a large bycatch component of several fisheries across its range, post-release stress studies have shown that the species is very resilient to capture stress from gillnet, trawl, and longline gear (Frick et al. 2009, Frick et al. 2010a, 2010b, Braccini et al. 2012), suggesting that this species is likely to have high post-release survival rates from a range of fishing methods.
In Western Australia, reported catches of the Port Jackson Shark for marine aquaria ranged from 197 to 664 specimens per year between 2008 and 2012 (Fletcher and Santoro 2013).
Recreational fishers occasionally catch the Port Jackson Shark, but it is not specifically targeted because of its low flesh quality. A survey of recreational boat anglers on the lower west coast of Western Australia estimated that the recreational catch by this sector of the recreational fishery was 273 individuals in the period from September 1996 to August 1997 (Sumner and Williamson 1999), while the estimated annual catch during 2011–12 by recreational fishing from boat licence holders was 2,200 (Ryan et al. 2013). These levels of catch are very minor when compared to commercial catches.
|Conservation Actions:||The only specific management regulation that exists for the Port Jackson Shark is the recreational fishing trip catch limit for sharks imposed by Western Australia (four of any species). No other states have bag or size limits that cover this species. However, site attached species such as the Port Jackson Shark may also benefit from habitat protection and suitably designed and implemented no-take zones, where all forms of harvesting or fishing are excluded. Commercial collectors of live specimens for the aquarium trade are normally licensed by state governmental legislation. Large commercial aquaria are able to successfully breed the species in captivity, reducing the reliance on wild caught animals. The occurrence of this species close inshore offers refuge from some larger commercial fisheries.|
|Citation:||Huveneers, C. & Simpfendorfer, C. 2015. Heterodontus portusjacksoni. The IUCN Red List of Threatened Species 2015: e.T39334A68625721.Downloaded on 19 September 2018.|
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