Investigations of Grey Nurse Shark in Queensland to fulfil actions under the Recovery Plan for Grey Nurse Shark

(Carcharias taurus) in Australia regarding impact of divers, and establishment of a photographic database to improve

knowledge of migratory movements, localised site movements and estimation of bycatch.

by

Mike Bennett and Carley Bansemer School of Biomedical Sciences, The University of Queensland

December 2004

The views and opinions expressed in this publication are those of the authors and do not necessarily reflect those of the Commonwealth Government or the Minister for the Environment and Heritage. While reasonable efforts have been made to ensure that the contents of this publication are factually correct, the Commonwealth does not accept responsibility for the accuracy or completeness of the contents, and shall not be liable for any loss or damage that may be occasioned directly or indirectly through the use of, or reliance on, the contents of this publication. © Commonwealth of Australia 2004 This work is copyright. Apart from any use as permitted under the Copyright Act 1968, no part may be reproduced by any process without prior written permission from the Commonwealth, available from the Department of the Environment and Heritage. Requests and inquiries concerning reproduction and rights should be addressed to: Assistant Secretary Wildlife Conservation Branch Department of the Environment and Heritage GPO Box 787 Canberra ACT 2601

Table of Contents 1.0 Introduction 1 2.0 Grey Nurse Shark Biology 3

2.1 Taxonomy 3 2.2 Description 3 2.3 Habitat and Diet 3 2.4 Life History and Reproductive Biology 4

3.0 Grey Nurse Shark Distribution and Dispersal 6 3.1 World-wide Distribution 6 3.2 Australian Distribution 6

4.0 Grey Nurse Shark Reproductive Ecology and Migration Patterns 7 4.1 World-Wide Grey Nurse Shark Reproductive Ecology and Migration Patterns 7 4.2 Grey Nurse Shark Reproductive Ecology and Migration Patterns in Australia 8

5.0 Grey Nurse Shark Conservation Requirements 9 5.1 World-Wide Grey Nurse Shark Conservation 9 5.2 Grey Nurse Shark Conservation in Australia 10

6.0 Background to the Research Project 10 6.1 Project Summary (Brief description of project) 11

7.0 Work and Progress to date (December 2004) 13 7.1 Prior to the start of this project: 13 7.2 Progress on the Key Objectives of this project 13

7.2.1 Determine the occurrence and distribution of grey nurse sharks in southeast Queensland. 13

7.2.1.1 Visual Surveys 13 Flat Rock (protected) 15 Wolf Rock (protected) 18 Henderson Rock (protected) 21 Cherubs Cave (protected) 24 China Wall (not protected) 27 Hutchison Shoal (not protected) 29 Summary 30 7.2.2 Determine if video/photo identification techniques are a reliable non-invasive method to monitor the grey nurse shark populations and dynamics. 31

7.2.2.1 Sharks in the Wild 34 7.2.2.2 Sharks in Captivity 41

Summary 41 7.2.3 Determine whether the activities of divers affect the behaviour of grey nurse sharks. 44 Summary 45 7.2.3.1 Possible Future Experimentation 45

8.0 Bibliography 47

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1.0 Introduction There is global concern over the status of the grey nurse shark (Carcharias taurus) and it is listed as “Vulnerable” on the International Union for the Conservation of Nature (IUCN) Red List accordingly (9). The grey nurse shark is one of Australia’s most endangered marine species (9). Since the 1800s this species has been hunted for its oil, flesh, skin and fins. Historically, due to their fierce appearance and being mistaken for other sharks that pose a danger to humans, large numbers of grey nurse sharks were killed by recreational spear and line fishers and in shark control programs, particularly in south eastern Australia (9). The species has one of the lowest reproductive rates known amongst elasmobranchs and there have been demonstrated declines in populations in Australia and South Africa. Major threats to the recovery of grey nurse sharks include incidental capture by commercial and recreational fisheries, shark control activities, shark finning and ecotourism. It is thought that fishing activity, particularly recreational line fishing, is impacting severely on the existing grey nurse shark population (9). Grey nurse sharks are considered to have a very low ability to sustain fishing pressure, and despite the species’ protection in Australia further introduction of management actions have been required to reduce incidental captures (7). It is estimated that there are less than 500 individuals remaining on Australia’s east coast (28). As a result, the Australian east coast population has been listed as critically endangered under the Commonwealth’s Environmental Protection and Biodiversity Conservation Act 1999, and has also been given the highest level of protection under the Queensland Nature Conservation Act 1990 and the NSW Fisheries Act 1994 respectively. The numbers of grey nurse sharks in Queensland waters have not been observed to be >30 individuals at any given time (EPBC listing advice). Historical data obtained from the Queensland and New South Wales (NSW) shark control program demonstrate the degree of decline in grey nurse shark numbers along the east coast of Australia. During the early 1950s in NSW, up to 36 grey nurse sharks were caught per year. By the 1980s, it had decreased to three or less per year and over the last decade an average of one grey nurse shark has been caught per year (NSW Fisheries, unpub. data). In Queensland, the same trend has been observed, 90 grey nurse sharks were caught between 1962 and 1972 (8), and only 12 were captured between 1993 and 2002 (DPI unpub. data). From the mid-1990s, shark control program contractors received intensive shark identification training. This training reduced the possibility of misidentification; however there may be incorrect identification of sharks caught prior to this time and non-reporting may be an issue.

Concerns have been raised that pre-1992, two species of sharks were recorded as ‘grey nurse sharks’ consequently inflating the apparent numbers of C. taurus. “Sharks” (edited by John Stevens) was the only ‘definitive’ book on Australian sharks at that time, and grouped the sand tiger shark (Odontaspis ferox) with C. taurus under the common name of grey nurse shark. However, as O. ferox occurs off the Continental Shelf it is unlikely to be caught in the shark control program. Furthermore, since 1994, Last and Stevens “Sharks

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and Rays of Australia” (23) has been the definitive text for shark identification and differentiates the two species.

During 2002, NSW Fisheries and Queensland Parks and Wildlife Service (QPWS) undertook tagging studies to instigate a tagging re-sighting program to monitor the populations’ recovery. A total of 27 sharks were tagged during 2002 in Queensland and NSW and more than 90 % of these have been re-sighted at least once (NSW Fisheries, 2003). All five sharks tagged in Queensland have been re-sighted at least once as far north as Yeppoon (G. Wathen, pers.comm.) and as far south as Forster, NSW (D. Harasti, pers. comm.). Given the large population decline, grey nurse sharks are in urgent need of improved biological understanding to guide in the design of more effective conservation actions (or policy) in Australia and worldwide. Little information is known about the biology, distribution, dispersal in any of the regions where it still occurs such as southern Africa, western Australia, southeastern and South America. Without this information it is difficult to develop conservation measures necessary to ensure the recovery of the critically endangered grey nurse shark along the east coast of Australia. The estimated time to quasi-extinction (years elapsed for the population to consist of 50 or less females) of the Australian east coast grey nurse shark population, based on current estimates of abundance and known anthropogenic rates of mortality in 2002, is 13-16 years (worst-case scenario), 84-98 years (likely scenario) or 289-324 years (best-case scenario), providing all carcasses are being reported (28). However, if under-reporting of carcasses is occurring (i.e. only 50% are being reported), these estimates reduce to 6-8, 45-53 or 173-200 years respectively. Either way, in all scenarios modelled, the grey nurse shark population will continue to decline if no further steps are taken to remove anthropogenic sources of mortality. Sensitivity analysis revealed that population rate of change was most sensitive to changes in the survival probability of the smallest length classes (30). The mitigation against key threats including incidental capture by commercial and recreational fishers, is critical to ensuring the survival and recovery of the critically endangered grey nurse shark population on the southeast coast of Australia. Currently, little is known about grey nurse shark home ranges, nursery grounds, local movement corridors, migration routes and how these differ between the sex, pregnancy status and age of grey nurse sharks. This information is critical to identify where key threats are occurring and where they need to be mitigated against. The impacts of ecotourism (diving) was also identified as a key threat under the National Recovery Plan for grey nurse sharks (9), however no impacts of divers on grey nurse shark behaviour have been identified or quantified. This study will generate information on movements of grey nurse sharks over various spatial scales to better understand its biology and population status, both of which will assist in the effective management of the species. This will be achieved through non-invasive mark-recapture models and behavioural experiments aimed to determine the extent of which divers can impact on grey nurse shark behaviour. In summary, the research described in brief above will be used to provide the Australian east coast population from key threats to ensure this population is protected from extinction.

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2.0 Grey Nurse Shark Biology 2.1 Taxonomy Common Name: Grey Nurse Shark (Australia) Other Names: Ragged-tooth shark (South Africa), Sand-tiger shark (USA). Scientific Name: Carcharias taurus (Rafinesque, 1810) Figure 1: Identifying Features of the grey nurse shark (Picture by D. Harasti)

2.2 Description The grey nurse shark, Carcharias taurus (Rafinesque, 1810), is one of four species belonging to the Odontaspididae family (8). It is a large stocky species that grows to at least 320 cm total length (23). Colouration is grey to grey-bronze dorsally, with a paler off-white underbelly (23). Spots may occur on the caudal fin and posterior half of the body (23, 31) (Fig. 1). The teeth are similar in both jaws and are long and conical with a relatively short lateral cusplet on either side of the main cusp. The grey nurse shark has a conical nose, small eyes without nictitating membranes, dorsally-flattened head, long mouth that extends anteriorly beyond the eyes and five gill slits that are located before the pectoral fins. The first dorsal fin is positioned immediately before the pelvic fins, and the two dorsal fins and pelvic and anal fins are all approximately the same size. The grey nurse shark has a small pit on the upper side of the caudal peduncle and the caudal fin has a very elongated dorsal lobe (8, 19, 27, 28, 31). 2.3 Habitat and Diet Grey nurse sharks are often observed in the vicinity of inshore rocky reefs and islands, or near sandy-bottomed gutters and rocky caves, hovering just above the seabed at depths of 15- 40 m (27, 31). However, catch returns from shore-based fishing in South Africa report grey nurse sharks of all size classes from less than 10 m depth (36). Smale (2002) also observed a trend for greatest catches of grey nurse sharks in South Africa from shallow

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turbid waters of 15-18 oC. Grey nurse sharks have also been recorded in the surf zone, around coral reefs and to depths of around 200 m on the continental shelf (2, 8, 23, 31, 36). This species generally occurs in medium-sized aggregations, usually fewer than 20 sharks; those observed alone are thought to be moving between aggregation sites (31). Sharks exhibit a high degree of site fidelity once a site (gutter or cave) has been occupied (28). Recent New South Wales Fisheries survey data indicate that a group of 20 or more individuals would be a notable event. Gut analyses undertaken on 42 grey nurse sharks from the northwest Atlantic Ocean found that teleost fishes were the dominant prey comprising 65% of the diet (14). Elasmobranchs contributed to 35% of their diets, with skates (Rajidae) dominating this group (14). Gelsleichter’s (1999) study concluded that the diet of grey nurse sharks in the North Atlantic was particularly diverse reflecting the use of coastal depth regions (<10 m depth). In South Africa, grey nurse sharks have been reported to feed on a wide range of fishes including herrings, croakers, bluefishes, mackerels, butterfishes, snappers, eels, wrasses, mullets, sea basses, flatfishes, jacks and many other prey including small sharks and rays (including eagle rays and juvenile Carcharhinidae), squids, crabs and lobsters (3, 2, 8, 35). Along the east coast of Australia grey nurse sharks consume pilchards, jewfish, tailor, bonito, morays, blue groper, sea mullet, flatheads, yellowtail kingfish, small and juvenile sharks, squid and possibly some crustaceans (28). It is thought that grey nurse sharks may feed in groups, herding prey before feeding on them (8,11). A feeding hierarchy whereby the most dominant individual feeds first has also been suggested (20). Cooperative feeding has been observed on several occasions in Australia. At Wolf Rock in southeast Queensland four grey nurse sharks were observed feeding in a cooperative fashion on a school of squid (K. Phillips, pers. comm.). At Forster in NSW, a local dive operator observed three grey nurse sharks swim up from near the bottom to circle and then feed on a large school of jewfish and kingfish and then return to the bottom. After these three sharks returned to the bottom another group of smaller grey nurse sharks left the bottom to feed on the schooling fish (N. Marsh, unpub. manuscript). 2.4 Life History and Reproductive Biology There is limited information available about the reproductive biology of grey nurse sharks in Australian waters. Most of what is known has originated from studies in South Africa, southwest Atlantic or in the United States (9). The life history characteristics of grey nurse sharks render them particularly vulnerable to over-exploitation, i.e. a relatively slow growth rate (taking 6 - 7 years for males and 9 - 10 years for females to mature), and low fecundity (producing only two pups per litter every second year) greatly reduce the species ability to sustain fishing pressure (7). Maximum size attained is 220-270 cm total length (TL) for males and 300-320 cm TL for females (7).

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The average life span of grey nurse sharks in the wild is unknown. A female grey nurse shark held in the Sydney aquarium has so far lived for 15 years. Furthermore, she was captured as a mature female measuring 2.2 m TL and it is likely that this particular female is at least 21 years old (G. Willis, pers. comm.). Others have lived for over 16 years in captivity in South Africa (16). It is likely that larger specimens in the wild are much older and maximum age has been estimated at 35 years (37). Reproductive strategies utilised by the grey nurse shark include intra-uterine cannibalism followed by oophagy (2, 8, 13). Multiple copulations of female grey nurse sharks by different males has been suggested (15), and observations of the southwest Atlantic grey nurse shark population during peak mating periods have reported a predominance of males (2:1) suggesting that there is competition for mates among males (24). Further, supporting this theory are observations of agonistic behaviour among males during pre-copulatory behaviour in captivity during which a dominance hierarchy is established with the dominant male mating with the female (14). The fertilised eggs develop in the paired uteri. Embryos develop teeth at about 10 cm total length and at about 55 cm TL escape from their egg capsules to feed on uterine egg capsules containing eggs and embryos and free embryos (23). The first to hatch has the advantage of being larger and the first to develop functional dentition, (17) allowing it to devour its siblings. Gestation is thought to take 9 – 12 months and at birth pups measure on average 1 m TL (23). In Australia, it appears that grey nurse sharks give birth at select pupping grounds (11), although divers rarely see newborn pups during visual surveys (C. Bansemer, pers. obs.). Pregnant females avoid giving birth in embayments and areas of low salinity and prefer coastal, rocky reefs (28). A biennial reproductive cycle is a common strategy in most galeoid sharks (6). Studies in the southwest Atlantic have observed mature females at different reproductive stages at different sites at the same time. For instance pregnant females were observed in Brazil and yet at the same time non-pregnant mature females were observed in Argentina (24). These observations suggest that grey nurse shark reproduction is biennial, which results in a maximum of two young per litter (one in each uterus) every two years (13). A biennial reproductive strategy has also been suggested for the northwest Atlantic population (5). The precise timing of mating and pupping in Australian waters is unknown (11). However, scuba divers have observed recently born pups in winter and early spring, which is consistent with observations from the United States and South Africa (28). In South Africa, mating occurs tropical waters in late spring with pregnant females moving southwards each year to give birth in early spring, then returning northward (9). On the US Atlantic Coast, the mating season extends from late winter to early spring off Florida, and during autumn off North Carolina (12). The timing of mating and pupping in Australian waters appears variable along the Australian east coast. In Queensland, Australia, divers have reliably observed fresh mating scars on sharks at Wolf Rock throughout the seasons however copulation was only observed at Wolf Rock in late spring of 2002 and 2003 (K. Phillips, pers. comm.). Mating scars on female sharks were also observed at Flat Rock and Henderson Rock in mid-/late winter

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2002 and in late spring/early summer 2003 (C. Bansemer, T. Jackson pers obs). Grey nurse sharks at Fish Rock in NSW have been observed with fresh mating scars during the winter months with mating behaviour observed in mid-/late winter 2001 (N. Hitchens & D. Harasti, pers. comm..). Sharks with mating scars have also been observed in NSW in late summer/early autumn (26). In mid-/late winter 2001, the birth of a grey nurse shark was observed; one pup was born in the late morning at Julian Rocks, Byron Bay (9). Reproductive ecology of grey nurse sharks appears to vary between populations and difference in timing may be a result of ecological conditions, e.g. water temperatures (24). 3.0 Grey Nurse Shark Distribution and Dispersal 3.1 World-Wide Distribution Grey nurse sharks have been recorded from the Mediterranean Sea and the Atlantic Ocean off Senegal, Ghana, southern Nigeria to Cameroon, Canary Islands, Cape Verde Islands, Bahamas, Bermuda, the eastern coast of the United Stated and Argentina to southern Brazil (N. Marsh unpub. manuscript). In the Pacific Ocean, they have been recorded from Japan, China, Vietnam and Australia. A small number were also recently observed in Milne Bay, Papua New Guinea. In the Indian Ocean, the grey nurse shark has been recorded from Western Australia, South Africa, southern Mozambique and along the Red Sea coastline (N. Marsh unpub. manuscript). 3.2 Australian Distribution In Australia, grey nurse sharks have been recorded from Rockhampton and Mackay in Queensland (DPI unpub data) around most of the southern half of the continent and northwards to Shark Bay in Western Australia, although the species is uncommon in Victorian, South Australian and Tasmanian waters (7). Grey nurse sharks have been caught in the Arafura Sea off the Northern Territory by Taiwanese long-liners (32) though they have not been recorded from the Great Australian Bight (9). Grey nurse sharks are no longer found at several sites along the east coast where they were dominant during the 1950s and 1960s (9). These sites included Brush Island where in the past (1950/60s) aggregations of 30 individuals could be observed (27). Anecdotal reports by divers and spear fishers in Queensland indicate that aggregations of 30 individuals could once be observed at Flat Rock and Wolf Rock (V. & R. Taylor, S. Urwin, B. Cropp, T. Long, pers. comm.). Aggregations were also observed at Flinders Reef off North Moreton Island (V. Taylor, pers. comm.). The distribution of grey nurse sharks is now thought to be restricted to coastal waters off southern Queensland, the entire New South Wales coast and the southwest waters of Western Australia (9). The eastern and western populations are considered separate as the species is thought to only normally migrate north-south within a limited non-overlapping range (9). Resolution of the genetic status of the populations is required (see, e.g. 21).

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Sites where grey nurse sharks form regular aggregations may play an important role in breeding (pupping and/or mating activities) and are thought to be critical for grey nurse shark survival (1). In Queensland, a “key aggregation site” is defined as where anecdotal, historical data have shown that grey nurse sharks aggregated in numbers of five or more and where an aggregation of five or more individuals has been observed during a single dive since 2001 (1). Previous research has identified the following key aggregation sites in Queensland: Wolf Rock (Rainbow Beach), China Wall, Cherubs Cave and Henderson Rock (Moreton Island), Flat Rock (Stradbroke Island) (9), Hutchison Shoal and Gotham City (near Flinders Reef off Moreton Island, Moreton Bay Marine Park) (1). 4.0 Grey Nurse Shark Reproductive Ecology and Migration

Patterns 4.1 World-Wide Grey Nurse Shark Reproductive Ecology and Migration Patterns A considerable number of studies around the world on grey nurse sharks have found that this species exhibits differing degrees of segregation according to age, sex and for female sharks whether or not they are pregnant. The ecological factors influencing the reproductive cycles of elasmobranchs are mostly unknown (18). Migration patterns of grey nurse sharks in relation to timing of mating, gestation and nursery grounds are unknown through most of the species range (24). Some information on the reproductive ecology is available from the NW Atlantic (12,13), South African populations (2) and the SW Atlantic populations (12, 24, 34). Studies in South Africa have identified grey nurse shark nursery areas in shallow inshore warm temperate waters of the Eastern Cape where juveniles are known to occur throughout the year (2, 36). Sexual segregation has been reported for adult grey nurse sharks in southeastern Africa (29). Mating there occurs towards the end of Spring and full-term pregnant females move southward during winter each year from Kwa Zulu-Natal to the Eastern Cape region to give birth in early spring (2), after which they return northwards. The precise whereabouts and movements of mature males outside the mating season are unknown (2). Along the eastern seaboard of the USA (NW Atlantic) between Cape Cod and Cape Hatteras juvenile grey nurse sharks are seen aggregating with the mature male population (12). Observations of juveniles (< 2 m) congregating separate from the adult population is apparent and it appears that they prefer shallow sheltered waters (36). However, in the US juveniles have been observed congregating with mature male sharks. For example, mature males and juveniles occur between Cape Cod and Cape Hatteras where as mature pregnant females inhabit more southern waters between Cape Hatteras and Florida (12). Mating occurs in southern waters where the pregnant females also give birth (12). Studies in the SW Atlantic have shown that mature males, females and some juveniles occur in Argentinean and Uruguayan waters during late spring, summer and autumn. Mating has been suggested to occur in Argentinean waters in summer and is mostly complete by late summer to early autumn and pregnant females occur in the warmer waters of southern Brazil, where they give birth (24).

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Several small grey nurse sharks have been reported from Argentinean and Uruguayan waters indicating that either some pupping is occurring in southern waters or that at least some pups and juveniles are dispersing southwards (24, 25). Pregnant females in the SW Atlantic congregate separately from ‘resting’ mature females and males as the number of mature females in Anegada Bay, Argentina is half that of males, where 95% of catches in the same season in southern Brazil are pregnant females (34). Hence the mature female population is split in two, with gravid females in the north (Brazil) and non-pregnant females engaged in mating activities in the south (Anegada Bay). Grey nurse shark migration in the SW Atlantic is more similar to the NW Atlantic rather than the South African one. Obvious differences include the area where parturition occurs and the direction of migration by pregnant females. In South Africa, pupping occurs in temperate waters (off the Cape coast) while in the NW and SW Atlantic it occurs in subtropical waters (off the Carolinas and Florida, and off Brazil, respectively). For the gestation and pupping, pregnant females move pole ward in South Africa, towards the equator in the SW Atlantic (24) and the NW Atlantic females do not appear to move (12). 4.2 Grey Nurse Shark Reproductive Ecology and Migration Patterns in Australia Relatively little is known about the migratory habits of grey nurse sharks in Australian waters. Evidence suggests migrational movement, possibly in response to water temperatures, occurs up and down the east coast (between southern Queensland and central New South Wales) (9). The migration may be northwards in autumn and winter and southwards in summer (supported by the observations of dive shop operators), the opposite of that documented for grey nurse sharks in southern Africa (31). Recaptures of tagged sharks in south eastern Africa indicated southerly movements of 500 to >1200 km (31). Individuals in southeastern Australia have been observed travelling in excess of 800 km (29). Dive charter operators regularly report seeing grey nurse sharks at the same locations on a seasonal basis on the east coast of Australia, suggesting that the species exhibits some degree of site fidelity (9), making it vulnerable to localised pressures in certain areas (1). Grey nurse sharks also exhibit localised movements. Two individuals tagged with acoustic tags at Flat Rock were recorded travelling up to 1200 m away from their aggregation sites to feed at night (1) before returning to their “normal daytime site”. In southeast Australia dispersal related to reproductive ecology has been inferred through sightings by divers of grey nurse sharks of different sex and reproductive status in different areas. Several of these reports have been subsequently confirmed by tagging and re-capture studies (22). Current observations indicate that there is variation in migration patterns and reproductive ecology according to location. For the Australian east coast population it is even possible that the grey nurse shark population at Wolf Rock and northwards are behaving differently than the NSW and southern Queensland population.

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In Queensland, male grey nurse sharks predominate at one southern Queensland site (Flat Rock) where they have been reported from early mid-autumn to early summer, however most regular sightings occur in late winter. At a further three locations in southern Queensland (Henderson Rock, Cherub’s Cave and China Wall) the ratio of males to females appears more equal and sharks have been observed at these sites from mid-winter to mid-summer. At Wolf Rock, the most northern identified aggregation site for grey nurse sharks along the east coast of Australia, predominately large females aggregate year round. Males are only observed during a few months of the year that coincide with observations of mating scars and copulation at this site (K. Phillips, pers. comm. & C. Bansemer, pers. obs.). There have also been three reports of grey nurse sharks being captured off Yeppoon in Queensland. Two were caught simultaneously from a depth of 41 m during bottom fishing about 40 km off Yeppoon (with more possibly present due to the earlier loss of some hooks) and the third about 70 km offshore in about 72 m by a commercial fisherman (M.Cappo, pers. comm.). In NSW it is thought that females head south over summer, and over the winter period, migrate north and meet up with the males to reproduce (26). Historically, about three-quarters of the catch from beach meshing operations off central NSW during mid-/late winter to mid-spring composed of females (33). It is also thought that males may move out into deeper water over the summer months (33). In Australia, no general pattern of reproduction-linked migration can be confirmed and it is thought that it may differ between regions. 5.0 Grey Nurse Shark conservation requirements 5.1 World-Wide Grey Nurse Shark Conservation The decline of grey nurse sharks has been identified by the IUCN, which has listed the grey nurse shark as globally Vulnerable. This species is also fully protected in South Africa, Namibia and Florida (USA) (7). Grey nurse shark reproductive strategies (e.g. mating, gestation and nursery grounds) for a particular population often occur in different management regions (states or even countries). To ensure a population is managed effectively requires coordination between the relevant management regions. Globally, incidental capture by fishers in areas of high-localised fishing pressure has affected whole populations. For instance, with the SW Atlantic grey nurse shark population; sharks mate in Argentina and spend the gestation period in Brazil. Thus, a management strategy involving Brazil, Uruguay and Argentina is required to effectively manage the SW Atlantic population of C. taurus (24).

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5.2 Grey Nurse Shark Conservation in Australia The Australian east coast population of grey nurse sharks utilise Queensland and NSW State waters within in 3 km of the coast and Commonwealth waters (3 – 200km). Consequently, management of this population needs to be coordinated amongst these management jurisdictions. The east coast population of grey nurse sharks is listed as critically endangered and the west coast population as vulnerable under the Environment Protection and Biodiversity Conservation Act 1999 (EPBC Act). The Commonwealth Government (Environment Australia) released the National Recovery Plan for Grey Nurse Sharks (Carcharias taurus) in June 2002. In Queensland, in December 2003 the east coast population was listed as “endangered” under the Nature Conservation Act 1992 (Nature Conservation (Wildlife) Regulation 1994) and four aggregation sites were identified as critical to the survival of grey nurse sharks. Within 1200 m of a central coordinate of these sites all fishing activities are banned or restricted (under QFS legislation) and diving activities are managed (under QPWS legislation). In New South Wales grey nurse sharks are listed as “endangered” under the Fisheries Management Act 1994. NSW Fisheries declared the grey nurse shark vulnerable and protected it in 1984, and in 1994 its status was upgraded to “endangered”. In addition, in December 2002 they identified and awarded some protection at 10 grey nurse shark aggregation sites. Around each of these sites there is now a 200 m critical habitat and a 800 m buffer zone within each various forms of fishing are restricted and there is a Code of Conduct for diving with grey nurse sharks (1). The population does not appear to have the capacity to recover unless anthropogenic mortality is eliminated (30). Additional mortality, even at apparently low levels, could further reduce population growth and lead to potentially catastrophic reductions in population size within relatively short time frames such as decades. Therefore, it has been suggested that effective management of grey nurse sharks can only be achieved by the removal of all fishing-related mortality (4) from important habitat areas within south-eastern Australia, accompanied by a reduction in overall fishing rates to prevent the possibility of merely displacing fishing activity (30). 6.0 Background to the Research Project. The Recovery Plan for grey nurse shark (Carcharias taurus) in Australia was released by Environment Australia in June 2002 and since then Queensland Parks and Wildlife Service (QPWS) has undertaken a range of activities to fulfil the objectives and actions outlined in the plan. This project proposes further activities covering other actions in the plan. The east coast population of grey nurse sharks is listed as critically endangered under the Environment Protection and Biodiversity Conservation Act 1999 (EPBC Act). Grey nurse

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sharks mainly inhabit coastal waters so it falls to State agencies to carry out the majority of research to fulfil the objectives of the recovery plan. The Queensland Parks and Wildlife Service is working with New South Wales Fisheries in the development and upkeep of a sightings database for the grey nurse shark east coast population and will continue to work with them to develop an integrated database showing movements across jurisdictions. This database will be made available to the Department of the Environment and Heritage. 6.1 Project Summary (Brief description of project) The proposed project will focus on collecting scientific information about the critically endangered grey nurse shark in southeast Queensland to fulfil actions outlined in the Recovery Plan for the Grey Nurse Shark (Carcharias taurus) in Australia (Environment Australia 2002), as well as providing additional information to guide future management actions. The proposed research will involve: • regular visual and video/photo identification surveys (Action H.3. Establish a

tag/resighting program to improve knowledge of: o demography and migratory movements; o localised site movements; and o estimation of bycatch levels.);and

• undertaking preliminary research to determine any potential impacts of divers on grey nurse shark behaviour (Action E.4 Research is conducted to determine the impacts of scuba diving.)

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Table 1. Key Objectives

Objectives Activities to be undertaken (detail of methods and who is responsible)

Start Date

Finish Date

Determine the occurrence and distribution of grey nurse sharks in southeast Queensland.

Regular visual surveys and video/photo identification surveys will be undertaken at identified key aggregation sites and potential aggregations sites by scuba divers (QPWS).

Funding received February 2004.

December 2004.

Determine if video/photo identification techniques are a reliable non-invasive method to monitor the grey nurse shark populations and dynamics.

A catalogue of video and photographs of grey nurse sharks will be collated with the goal of determining the viability of using this method to monitor grey nurse shark populations in the wild (QPWS/UQ).

Funding received February 2004.

December 2004.

Determine whether the activities of divers affect the behaviour of grey nurse sharks.

The use of SCUBA gear and the behaviour of divers may be causing an unacceptable disturbance of grey nurse sharks and specific research is required to identify such impacts, if any. For this project the use of rebreathing apparatus will be compared with divers using normal SCUBA gear, to explore possible differences in reactions by sharks to approaching divers. (UQ).

Funding received February 2004.

December 2004

Preparation of progress report

Progress report outlined the research progress to date (QPWS/UQ)

May 2004

Preparation of final report Final report will be presents project results (QPWS/UQ)

December 2004

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7.0 Work and Progress to date (December 2004) University of Queensland Animal Ethics Committee clearance for this project has been obtained: Biology, distribution, dispersal and conservation requirements of the grey nurse shark, Carcharias taurus (Rafinesque 1810). AEC Approval number: SBMS/196/04/DEH 7.1 Prior to the start of this project: Since 2001 QPWS has been involved in grey nurse shark research, monitoring and in working with QFS to develop management. In 2001, preliminary surveys were undertaken to begin to identify key aggregation sites in southeast Queensland. In 2002, QPWS was awarded funding from NHT Coast and Clean Seas Program to assist with a more detailed project to obtain data on the abundance and distribution of grey nurse sharks in southeast Queensland and to determine if grey nurse sharks in Queensland migrated between NSW and Queensland. Collaborative work was also undertaken with CSIRO Hobart to begin to understand the daily movement patterns of grey nurse sharks around the critical habitats. In 2003, effort was put in encouraging the diving community to report on sightings to QPWS and to put in place management to protect grey nurse sharks at the sites in Queensland were they are known to aggregate. In 2004, monitoring of key aggregation sites in SE Queensland were continued to increase knowledge on occurrence of grey nurse sharks at these sites year round. Photographs and video sequences were taken and collected from the volunteer diver network by C. Bansemer to facilitate long-term monitoring of the grey nurse shark population size, hooking incidence and recovery over time.

7.2 Progress on the Key Objectives of this project.

7.2.1. Determine the occurrence and distribution of grey nurse sharks in southeast Queensland.

7.2.1.1. Visual Surveys A significant part of this project was dedicated to conducting visual surveys (counts) of the grey nurse shark population in southeast Queensland. In order to survey a large number of sights as frequently as possible volunteer recreational scuba divers were called upon to conduct many of the surveys. To facilitate this, considerable effort was placed on training volunteers to identify grey nurse sharks and how to observe and record other important information about the shark. Emphasis was also placed on encouraging the recreational divers to forward photographic and video footage of grey nurse sharks for the purpose of identification and tracking individuals movements and duration at and between

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aggregations sites. To facilitate this, three large-scale workshops were held at Underwater World on the Sunshine Coast, Sea World on the Gold Coast and at the Queensland University of Technology, Brisbane. The abundances of grey nurse sharks in the survey were quantified using underwater visual counts of sharks throughout a dive. During the dive, divers recorded the total number of sharks present, and when present, the total length and sex (where possible) of each individual. Total lengths were recorded in three size classes: 1 - 2 m, 2 - 3 m, and over 3 m. In addition, the presence of mating scars, tags and fishing gear (hooks, wire traces, lines, etc.) was also noted. Where photos were provided these details were checked against these photos. The following data provide a brief analysis of all visual surveys (1991-2004) conducted at the four protected grey nurse shark aggregation sites (Flat Rock, Cherubs Cave, Henderson Rock and Wolf Rock), and at other sites where grey nurse sharks have been reported [some of the latter sites may warrant future protection, but are currently data deficient with respect to grey nurse shark occupancy]. Visual surveys were conducted at a total of 29 sites in Queensland, with grey nurse sharks observed at 19 of these. Grey nurse sharks were encountered, but on rare occasions and/or in small numbers, at the following sites:

o China Wall (details provided later); o Hutchison Shoal (details provided later); o Flinders Reef (3 sharks on 1 Feb 2003, 1 shark 15 February 2004 and 1 shark on

26 August 2004); o Dune Rocks (Point Lookout, North Stradbroke Island: 1 shark observed on 9

March 2002); o Gneering Shoals (off Mooloolaba: 1 shark observed on 26 September 2001); o Gotham City (near Flinders Reef off Moreton Island: 1 shark observed on 17 July

2004); o Jew Shoal (off Noosa: 1 shark observed on 26 November 2002, 1 shark observed

28 September 2003, 2 sharks observed regularly between May and July of 2004); o Mudjimba/Old Woman Island (off Mooloolaba: 1 shark observed 13 July 2003); o Off North Point Fraser Island (1 shark observed: 12 February 2004); o Sandy Cape Shoals (1 shark observed on 15 July 2004); o Yeppoon (2 sites off Yeppoon: 1 shark caught and released about 70 km offshore

on 6 October 2002, 2 sharks caught and released about 40 km offshore in 40 m water on 16 May 2004);

o St Paul Wreck (off Nth Moreton Island: 1 shark observed on 10 August 2003); o Shag Rock (off Nth Stradbroke Island: 1 shark observed on 3 August 2002, 20 July

2003, 29 June 2004 and 2 sharks were observed on 26 July 2004); o Smith’s Rock (off Moreton Island:1 shark observed on 2 August 2004).

The following sites are aggregation sites (both protected and not protected) where grey nurse sharks have been recorded relatively consistently over time:

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Flat Rock (protected)

Flat Rock is located 4.1 km off the northeastern tip of North Stradbroke Island. Depths around Flat Rock vary from 10 to 35 m. Two rock formations break the surface at the site; the smaller of the two is known as Little Flat. Flat Rock is characterised by a sandy bottom from which steep walls of granite arise to form several distinctive gullies. One of the gullies is located off the rock’s northern tip and the other runs the length of the broader southern edge. The gully on the southeastern side is an area known as the Shark Gutter, named because grey nurse sharks aggregate in the area. Table 2 shows the total number of surveys/dives conducted per month from 1991 to 2004. It is important to note that prior to 2001 surveys were conducted infrequently, or not at all, in many months of the year. These data should be used in the interpretation of Figures 2, 3 and 4). Table 2. Total number of surveys/dives conducted by C. Bansemer, QPWS and recreational divers at Flat Rock per month.

1991 1992 1993 2000 2001 2002 2003 2004 Jan 0 0 0 0 0 0 0 0 Feb 0 0 0 0 0 0 0 3 Mar 0 0 0 0 0 1 3 0 Apr 0 0 0 0 0 0 4 0 May 0 0 0 0 0 2 4 0 Jun 2 3 0 2 1 16 2 6 Jul 2 4 0 0 3 17 28 15 Aug 0 1 1 1 6 6 9 9 Sep 0 0 0 0 3 4 6 8 Oct 0 0 0 0 4 2 2 5 Nov 0 0 0 0 0 1 5 8 Dec 0 0 0 0 0 0 1 0

Figure 2 shows that grey nurse shark numbers at Flat Rock generally peak during July, although in recent years, there has been a tendency for grey nurse sharks to be observed from June through to late November.

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Month

Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec

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of sh

arks

0

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30 19911992199320002001200220032004

Flat Rock

Month

Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec

Num

ber

of sh

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0

5

10

15

20

25Flat Rock1991

1992199320002001200220032004

Figure 2. The maximum number of sharks observed on a single survey dive for each month.

Figure 3. Average number of sharks observed per survey dive for a given month.

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Comparison of Figure 2 with Figure 3 demonstrates that the average number of sharks observed across all surveys in a given month is considerably less (usually les than half) of the maximum number of sharks observed in a single dive in any given month. Fluctuations in observed numbers suggests that grey nurse sharks may be moving between recognised aggregation sites or, while still in the general vicinity, are not being seen by divers. This may be due to their use of other parts of the aggregation site due to disturbance or other, unknown, factors. Figure 4 is included to demonstrate more clearly that the maximum numbers of grey nurse sharks observed in the months from July to November 2004 was considerably greater than in previous years.

Month

Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec

Num

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of sh

arks

0

5

10

15

20

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30 2001200220032004

Flat Rock

Figure 4. Maximum number of sharks observed at Wolf Rock during any single survey divefor given months over the period 2001 - 2004.

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Wolf Rock (protected)

Wolf Rock is located 6 km northeast of Rainbow Beach. The formation consists of four major pinnacles that line up in a northeasterly direction. Two of the pinnacles are submerged. Between the two exposed pinnacles there is a 10 m deep and 2 m wide trench. Wolf Rock is characterised by steep walls on all of the pinnacles. There is a fifth pinnacle on the southwest side rising to a depth of approximately 19 m. A series of gutters, followed by a rock formation rising to a depth of 22 m can be observed northwest of the main rock. Table 3 shows the total number of surveys/dives conducted per month from 1997 to 2004. These data are necessary for interpretation of the maximum and average number of sharks (Figures 5, 6 and 7) observed during any month. Note: no dive survey data are available prior to 1997, in contrast to the Flat Rock data that include surveys from 1991. Table 3. Total number of survey dives per month at Wolf Rock.

1997 1998 2000 2001 2002 2003 2004 Jan 0 0 1 1 12 2 2 Feb 0 2 0 0 7 9 7 Mar 0 0 0 0 7 9 0 Apr 0 0 0 0 11 10 0 May 0 0 0 1 10 3 6 Jun 0 0 0 0 7 3 9 Jul 0 0 0 3 13 1 10 Aug 0 0 0 2 5 0 8 Sep 0 0 0 0 8 1 11 Oct 0 0 0 8 3 0 9 Nov 0 0 0 6 5 1 11 Dec 1 0 0 13 9 5 1

Figure 5 shows that in more recent years (2001 to 2004) grey nurse sharks have been observed almost throughout the year at Wolf Rock. The largest numbers of grey nurse sharks being observed in April 2003. The month in which the greatest number of sharks is seen at one time varies between years. In 2001, for which there are survey data for most months, numbers peaked in December; for 2002, in January; for 2003, in April and; for 2004, in February.

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Month

Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec

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of sh

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0

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30 1997199820002001200220032004

Wolf Rock

Month

Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec

Num

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0

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30 1997199820002001200220032004

Wolf Rock

Figure 5. The maximum number of sharks observed on a single survey dive for each month.

Figure 6. Average number of sharks observed per survey dive for a given month.

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When comparing Figure 5 and Figure 6, in general the average number of sharks observed (across all surveys in a given month) is considerably less than the maximum number of sharks observed in a single dive across all dives for the same given month. This demonstrates that the numbers of grey nurse sharks present and visible to divers vary considerably across a given month. Figure 7 shows that in 2001, the first year where there were fairly comprehensive surveys, grey nurse sharks were observed in lower numbers and less frequently than in later years. No sharks were observed between February and June. In 2002, grey nurse sharks were in every month of the year. In 2003, grey nurse sharks were observed in all months with the exception of August and October. In 2004, sharks were observed in all months except March and April. It is interesting that in each year where sharks were not present in one or more months that the months varied in each year.

Month

Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec

Num

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of sh

arks

0

5

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252001200220032004

Wolf Rock

Figure 7. Maximum number of sharks observed at Wolf Rock during any single survey divefor given months over the period 2001 - 2004.

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Henderson Rock (protected) Henderson Rock is located 4.5 km off the eastern side of Moreton Island. The ‘rock’ consists of several extensive granite outcrops. From the top of the pinnacle, which lies at about 12 m, the rock slopes gradually at first, then more steeply to about 24 m. Before the 24 m mark there are several ledges, overhangs, and caves whose entrances are often obscured by thick kelp (Elkonia sp.). The area is characterised by kelp beds on the western side leading into bare rock on the top of the site, which then leads to several 2 m high walls with hidden swim-throughs. There are also large caverns located further away from the site, at a depth of around 25 m. To the south and east of the base of the pinnacle there is a long deep gutter that leads roughly south to about 22 m. Table 4 shows the total number of surveys/dives conducted per month from 1992 to 2004. These data are important for the interpretation of Figures 8 and 9 as, for example, no surveys were conducted between December and May of any year prior to 2004. The occurrence of grey nurse sharks at this site during these months is effectively unknown. Table 4. Total number of survey dives per month at Henderson Rock.

1992 2000 2001 2002 2003 2004 Jan 1 Feb 1 Mar Apr May 1 1 Jun 3 1 1 Jul 1 1 1 1 Aug 4 1 2 Sep 2 2 Oct 1 Nov 1 3 1 1 Dec

Grey nurse sharks are commonly seen in the later months of the year at Henderson Rock, with the highest number (nine) being recorded in August 2004 (Figure 8). These data have a similar trend to those for Flat Rock, but it must be noted that there have only been three survey dives in the December to May period in total, and the apparent absence of sharks should be interpreted as a deficiency in data collection.

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Month

Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec

Num

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of sh

arks

0

2

4

6

8

10

199220002001200220032004

Henderson Rock

Figure 8. Maximum number of sharks observed at Henderson Rock during any single surveydive for given months over the period 1992 - 2004.

The average number of sharks observed on dives conducted in each month shows a similar pattern, reflecting the relatively few survey dives conducted at this site. Only six individual months over the whole survey period (1992-2004) contained multiple survey dives. In those months where repeat surveys were conducted the number of sharks observed generally varied by approximately two-fold, suggesting that a greater number of survey dives is required at this site to generate more robust resident population estimates.

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Month

Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec

Num

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0

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4

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8

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199220002001200220032004

Henderson Rock

Figure 9. Mean number of sharks observed at Henderson Rock during all survey dives for anygiven month over the period 1992 - 2004.

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Cherubs Cave (protected)

Cherubs Cave is located 4.1 km off the eastern side of Moreton Island, near Henderson Rock. The depth at the site varies from 30 m to around 14 m on the main bommie. The main bommie consists of a single characteristic rock that extends out in a northerly direction. The area between this main bommie and others located around the site is abundantly covered with kelp (Elkonia sp.). Cherubs Cave is named after a cave system located under a large circular shaped bommie on the northwest side of the main bommie. The cave has four entrances that are difficult to find as they are covered with kelp. Thirty-five survey dives were conducted at Cherubs Cave over the period from 2000 to 2004, with approximately half occurring in 2002. The relative lack or absence of surveys in the months of December to May, and the relative low level of sampling overall should recognised in the interpretation of Figures 10 and 11. Table 5. Total number of survey dives per month at Cherubs Cave. 2000 2001 2002 2003 2004

Jan 0 0 0 0 1 Feb 0 0 0 0 0 Mar 0 0 0 0 0 Apr 0 0 0 0 0 May 0 0 3 0 0 Jun 0 0 2 1 0 Jul 1 3 0 0 1 Aug 0 3 1 0 1 Sep 1 1 2 2 2 Oct 0 0 0 1 0 Nov 0 1 6 0 1 Dec 0 0 0 1 0

Figure 10 shows a similar trend to that observed at Henderson Rock and as with Henderson Rock most surveys were undertaken at Cherubs Cave during the months when sharks were present. One point of interest is that the maximum number of sharks observed at this site was in 2002.

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Month

Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec

Num

ber

of sh

arks

0

2

4

6

8

10

20002001200220032004

Cherubs Cave

Figure 10. Maximum number of sharks observed at Cherubs Cave during any single survey dive for given months over the period 2000 - 2004.

As with the other Queensland sites, the mean number of grey nurse sharks seen across all surveys within a given month (where there are repeat surveys) is less than the maximum number observed. This suggests that sharks are constantly moving out of/between the critical habitat sites being monitored. The true dynamic nature of these movements is not very well known, although application of the non-invasive shark recognition protocol (see Section 7.2.2) should enable shark movements between sites to be quantified.

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Month

Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec

Num

ber

of sh

arks

0

1

2

3

4

5

20002001200220032004

Cherubs Cave

Figure 11. Mean number of sharks observed at Cherubs Cave during all survey dives for anygiven month over the period 2000 - 2004.

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China Wall (not protected)

China Wall is located 3.5 km off the eastern side of Moreton Island. As its name suggests, China Wall consists of an extensive granite wall rising from a depth of 32 m up to 16 m on the western side. Along the wall are several 3 m deep and 2 m wide gullies. On the northern side of the wall there is a granite arch that is 3 m high and 6 m wide. A similar arch 2 m high and 4 m wide can be found on the southern extent. At the midpoint of the site a granite plate rises out of the wall at a 28 m depth on an almost vertical angle. In the top part of the plate at about 22 m there is a 2 m wide swim-through known as the keyhole. Surrounding this site are many granite boulders with various caverns and overhangs. Most of the granite is covered in kelp. Table 6 shows that relatively few surveys (14) have been undertaken at China Wall over the last four years. However, all months except March, April and December have been surveyed at some time. Anecdotal accounts suggest that aggregations of more than five individuals have occurred historically at China Wall, but it was not until 2004 that an aggregation of five sharks was positively observed at this site. As with the other known aggregation sites, this table demonstrates the need to conduct year round surveys at each of the aggregation sites to determine the presence/absence of grey nurse sharks throughout the year. Table 6. Total number of survey dives per month at China Wall.

2001 2002 2003 2004 Jan 0 0 0 1 Feb 0 0 0 1 Mar 0 0 0 0 Apr 0 0 0 0 May 0 1 0 0 Jun 0 1 0 1 Jul 0 0 0 1 Aug 1 0 0 1 Sep 1 1 0 0 Oct 0 0 1 1 Nov 0 0 1 1 Dec 0 0 0 0

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Table 6 and Figure 12 demonstrate that while data are fragmentary there appears to be a similar trend to that observed at the other sites located off North Moreton Island (Cherubs Cave and Henderson Rock), with sharks commonly observed in the latter six months of the year. As only one survey was undertaken in any given month the average number of grey nurse sharks for this site is the same as the maximum number observed.

Month

Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec

Num

ber

of sh

arks

0

1

2

3

4

5

6

2001200220032004

China Wall

Figure 12. Maximum number of sharks observed at China Wall during any single survey dive for given months over the period 2001 - 2004.

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Hutchison Shoal (not protected)

Hutchison Shoal is the northernmost of a chain of shoals which runs south through Flinders Reef, Smith Rock, Brennan Shoal to Roberts Shoal, east of the Cape Moreton lighthouse. It lies 3.7 km north of Flinders Reef and comprises an extensive series of granite outcrops, narrow caves and ledges, overhangs and sharp, craggy pinnacles in depths from 12 to 30 metres. There have been many anecdotal records of grey nurse sharks at Hutchison Shoal over recent years. Data from these sites have typically only been submitted if sharks are sighted. During 2002, two surveys were conducted and sharks were recorded on both. The first was in September when 2 sharks were recorded, and the second in December when 7 sharks were recorded during a single dive. More comprehensive surveys are needed at Hutchinson Shoal year-round to confirm the presence/absence of sharks at this site and to confirm that it is a key aggregation site for grey nurse sharks in southeast Queensland. Table 7 shows that only twelve surveys have occurred at Hutchison Shoal over the last five years. Six of these surveys were conducted in 2004. There are no survey data for the months of January, March, April, May and August for any year. It was not until 2004 that an aggregation of five sharks was positively observed at this site. Similarly to all of the other aggregation site data, this table demonstrates the need to conduct year round surveys at each of the aggregation sites to determine the presence/absence of grey nurse sharks throughout the year. Table 7. Total number of survey dives per month at Hutchison Shoal.

2000 2001 2002 2003 2004 Jan 0 0 0 0 0 Feb 1 0 0 0 0 Mar 0 0 0 0 0 Apr 0 0 0 0 0 May 0 0 0 0 0 Jun 0 0 0 1 0 Jul 0 1 0 0 3 Aug 0 0 0 0 0 Sep 0 0 0 0 1 Oct 0 0 1 0 0 Nov 0 0 1 0 2 Dec 0 0 1 0 0

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Hutchison Shoal again shows a similar trend (Figure 13) with sharks more commonly observed in the latter six months of the year. However, an observation of four grey nurse sharks February 2000 highlights the need to undertake surveys throughout the year at these sites.

Month

Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec

Num

ber

of sh

arks

0

2

4

6

8

20002001200220032004

Hutchison Shoal

Figure 13. Maximum number of sharks observed at Hutchison Shoal during any single surveydive for given months over the period 2000 - 2004.

Summary There is a considerable quantity of data on the occupancy of these six sites stretching back, in some cases, to 1991. While these data are important to show seasonal trends in critical habitat use, the lack of uninterrupted monthly surveys is a problem. Also, the general lack of individual shark recognition introduces uncertainties into data interpretation, namely, “how many of the recorded sharks have been counted two or more times at the same or at different sites?”

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While these six sites are undoubtedly important habitats for grey nurse sharks, particularly utilised in the latter half of the year, we still lack good data on their use of these sites over the whole yearly cycle. 7.2.2. Determine if video/photo identification techniques are a reliable non-invasive method to monitor the grey nurse shark populations and dynamics. Background A recent ‘Review of Grey Nurse Shark Tagging Research’ convened by Environment Australia (now Department of Environment and Heritage, DEH) concluded that information on movement patterns and an ability to monitor the population status of grey nurse sharks is critical for their conservation. It is of the highest priority to ensure that this information is collected without impacting adversely on the sharks. Subsequently, a grey nurse shark-tagging program using standard fin tags was initiated. This provided much needed information about movements of 24 individual sharks and facilitated population estimates. Unfortunately, some tags were seen to be causing skin abrasions and other damage to the sharks and an independent review panel examined the issue of management of the tagged animals and produced guidelines for future tagging-based research. The panel strongly recommended that tagging programs be allowed to continue, but the use of less invasive procedures should be explored. Ideally, a non-invasive method needs to be developed to monitor the stability, recovery or continued decline of this population. One such method is individual identification based on surface features unique to individuals, and it forms an important method of study in animal behaviour, ecology and population biology (19, 38). This method enables individuals to be tracked through time to help define their range, site fidelity and to quantify habitat use. Studying social interactions, group composition and cohesion requires measurements of rates of these interactions or behaviours to enable accurate and replicated behavioural data to be obtained (38). This form of non-invasive monitoring of grey nurse sharks has not been investigated prior to this project. If adopted, this approach could allow individuals to be tracked through time, making it possible to determine such features as critical habitat use (previous section), pupping intervals, survivorship, rate of hooking incidence and life span. In combination, such individual measures can provide population level vital rates, including birth rates, mortality rates, and recruitment (39). Successful, individual photographic identification will fulfil the required management action to monitor the population’s status, movements and demography; a high priority for their conservation and recovery. Additionally, this method will enable regular opportunities to involve the community and engage volunteers to the project and educate the wider public about grey nurse sharks.

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Despite some skepticism about the potential use of visual census to identify and quantify grey nurse shark populations (based on concerns that natural markings change regularly on grey nurse sharks), preliminary studies have indicated that individual identification of this species is possible through natural markings and scars. Methodology Two approaches have been adopted: Firstly, in collaboration with Underwater World, Mooloolaba, we have been able to photograph their seven captive grey nurse sharks (4 females and 3 males) on a routine and fairly regular basis. The sharks are held under natural photoperiod and water temperature and exhibit behaviours (including mating) that appear to be similar to those displayed in the natural environment. The sharks are all mature individuals and are of a similar size to those routinely encountered by divers at aggregation sites. Photographs are taken of each of the sharks at regular intervals. Variations in skin pigmentation appear as either very dark, and usually small ‘spots’ or larger patches of grey, only slightly darker than the general body surface. Both types of pigment patch are visible in the photographs and have allowed the mapping of the unique patch pattern for each shark. A schematic outline of a shark has been developed to allow us to plot the size and pattern of patches on a temporal basis, and results indicate that the patterning has not changed during the study period so far. This preliminary result suggests that patch patterns could have use in the monitoring of wild populations. What is evident is that lighting conditions and/or the type of flash or camera system used does influence the number and darkness of spots observed. Our data suggest that the best results may be achieved by concentrating on a specific body region for analysis. The logical part of body to use would be around the pelvic region, as the gender can be easily determined, and which appears to be commonly pigmented. Using the pelvic region allows photographs of sharks in their natural habitat to be divided immediately into two groups – of males and females, which will reduce the time spent in analysing spot patterns and searching any future database. Future analysis will be undertaken to determine how many spots are needed to positively identify an individual, together with some indication of the degree of confidence of such identifications. Secondly, grey nurse sharks in the wild are also subject to visual, diver-mediated census at specific known aggregation sites at specific times of the year. Unique identifiers should allow gross movements of individuals to be determined between census dates. To encourage divers from the community to supply their photos and video of grey nurse sharks free workshops and competitions with prizes provided by Underwater World and Sea World are undertaken on a regular basis. To date, five public awareness/information events have been held to educate the diving fraternity about diving with grey nurse sharks to recruit underwater photographers/videographers to the project. Currently, there is a ‘grey nurse shark e-mail address’ where people can submit their survey data, photographs and video clips.

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This is an ambitious study that involves the collection and organisation of the photo/video database and regular maintenance to enable individuals to be recognised and tracked. The use of a web/email-based submission process to enable the diving fraternity to download images, video, monitor sightings and movements of identified grey nurse sharks is in the process of being developed. Design & Data Analysis Images of sharks are sorted and saved according to geographical locality, date, sex, left- or right-hand view of the shark. A schematic outline of a shark has been developed to plot the size and pattern of patches on a temporal basis. For photos taken in Underwater World, individual skin markings are measured (size and relative position) to determine how they change over time. Spot areas, inter-spot distances and distances to body features (e.g. fin bases) are measured and used to determine if ‘spot area’ or ‘spot position’ change significantly over time. The results define the ‘time-envelope’ over which unique identifiers could be used successfully in identifying an individual shark in the wild. To explore the effect of camera position relative to the target shark and possible confounding effects of lighting, photographic images of a specific body region (e.g. pelvic fin base area) are being taken under controlled conditions at Underwater World. Each of the six sharks (three female, three male) are photographed from the following angles -30°, 0°, +30° on a horizontal plane and repeated from 30° above and 30° below the shark. The nine images will be ranked as to their clarity of visualising a group of spots to determine which angles of photographing the fish produce usable data. Images of wild sharks will also be analysed for unique identifiers that allow gross movements of a few individuals to be determined between census dates. These individuals will be added to the Web page with information of where and when that photo was taken and any future photos identifying that particular individual will be added with similar information. Photographs of her entire body (both sides) have been taken, however, for the purpose of this review comment is restricted to one group of spots above the pelvic fin. The images show that spot patterning at this location is essentially unchanged and is visible even though there is considerable variation in photographic image quality, angle of the fish to the camera, lighting conditions, etc. Results to date: Five public awareness/information events have been organised to involve the diving community in this aspect of the project. The workshops were held at the end of May 2004: Two at Sea World (Gold Coast), two at Underwater World (Sunshine Coast) and one at the Queensland University of Technology (Brisbane). Each workshop ran for about three hours and was used to educate the diving public about diving with grey nurse sharks, and their current plight (see the following “workshop advertisement”). The workshops were also an avenue for recruiting underwater photographers to the project.

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A substantial photographic and video archive of over 1000 images of grey nurse sharks at various aggregation sites, taken over the last few years, is being catalogued. This resource is being examined to explore which images (taken by, for example, recreational divers) can be used to identify individual animals. 7.2.2.1 Sharks in the Wild An example of the effectiveness of photographic identification is that for two surveys, one undertaken on 31st July and one undertaken on 1st August 2004, the following information was provided: A total of three sharks were observed trailing various fishing tackle: One female, one male and one shark of unknown sex. Two individuals had jaw deformities (one male and one female), one male had two scars in both dorsal fins possible where Roto tags were once attached, and one male had a scar around his caudal peduncle probably as a result of tail rope once being attached. One male had a section of his second dorsal fin missing. A minimum of seven different females was observed between the 31st July 2004 and 1st August 2004. A maximum of 13 may have been observed (visual survey data). Of these three were observed on both days. With the males a total of 23 different males were identified over the two days. Of these four were observed on both days. As photographs are split into the sex of the shark and the side the photo was taken it is usually not possible to determine if a left and right photo is the same shark. Hence for each site and each survey the maximum number identified of either sex and either side is used for the minimum total number of different individuals of each sex identified. Photographic examples of sharks observed on both days.

35

Females: 1 August 2004 Right Hand Side

31 July 2004 Right Hand Side

36

1 August 2004 Left Hand Side

31 July 2004 Left Hand Side

37

Males: 1 August 2004 Right Hand Side

31 July 2004 Right Hand Side

38

1 August 2004 Left Hand Side

31 July 2004 Left Hand Side

39

The following photographs of the right hand side of a male shark at Flat Rock were taken on the 1 August 2004, 31 July 2004 and 6 June 2004 respectively. 1 August 2004 Male Right Hand Side

40

31 July 2004 Male Right Hand Side

6 June 2004 Male Right Hand Side

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7.2.2.2 Sharks in Captivity The grey nurse sharks at Underwater World have been photographed on a recurring basis over most of 2004. The following images are of Juliet, a large female shark and of Uncle Ray, a large male shark. The months in which the photographs were taken is indicated on each image. Juliet The four images of the left flank of Juliet show a clear spot pattern extending from just posterior to the pectoral fin to the level of the caudal peduncle. Twelve spots are indicated and numbered in image A. The same spots are identified in the other images (B – D). There are a number of important observations to be made from this study.

1. The twelve, arrowed, spots that were identified in February 2004 are still present and clearly identifiable ten months later (November 2004).

2. A total of fifty spots could be clearly identified on Juliet’s left side on each occasion indicating that a majority of spots do not undergo any marked change in this timeframe.

3. The lighting conditions do affect one’s ability to resolve spots, but as these images show, it is possible to identify unique patterns even if certain spots are not visible do to shadowing or overexposure of parts of the body.

4. The apparent position of the spots relative to each other and to parts of the body (e.g. fin bases) can change depending on whether the body is flexed and/or incident camera angle. However, these effects can be accommodated if the individual examining the images is aware of the possibility of parallax error.

Uncle Ray The two images of the left side of Uncle Ray illustrate that spot pattern recognition is possible even when the spots are not highly pronounced. Eighteen spots were identified in February 2004 and were still visible in December 2004 (white arrows). Interestingly, there were two additional spots visible in December 2004. Both of the ‘new spots’ were small and deeply pigmented, suggestive of a surface wound. These ‘spots’ may be the result of shark-shark interactions during the mating season. The fate of these spots will be monitored to see how long they persist. Summary Unique individual spot patterning can be used reliably to identify sharks in the wild, if the photographic images are of sufficient quality.

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43

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7.2.3. Determine whether the activities of divers affect the behaviour of grey nurse sharks. Background The National Recovery Plan for grey nurse sharks identified divers as a potential key threat to grey nurse sharks through impacting on their natural behaviour at key aggregation sites (8). In December 2003, QPWS put in place legislation to manage diver behaviour at grey nurse shark protection areas in Queensland. This legislation came about from a recommended Code of Conduct for divers as part of the National Recovery Plan. However, this code of conduct was not based on field trials and no data exists to demonstrate its effectiveness in removing impacts of divers to grey nurse sharks. The 2004 Annual Grey Nurse Shark Progress Report (required by and provided to DEH) states that a review should be undertaken within two years of the Code of Conduct for Diving with grey nurse sharks being introduced to determine its effectiveness in achieving its purpose. Methodology and Technique The aspect of the project that is examining whether diver activity affects grey nurse shark behaviour progressed according to plan. To date there have been four fieldtrips to conduct research. The population of sharks at Wolf Rock has been used as the experimental group. All shark-diver “interactions” during the experimental periods were recorded on digital videotape for subsequent analysis. The major focus has been to examine whether sharks exhibit specific behaviours, such as avoidance actions when in the proximity of divers using standard scuba gear (breathing compressed air and releasing exhaled air to the environment, = bubble-release) compared to divers using rebreathing apparatus (no bubble release or slight bubble release in a semi-enclosed rebreather is used). Wolf Rock Fieldtrips: Trip 1 – 1st February

Trip 2 – 26th February Trip 3 – 15th April

Trip 4 – (no experiments undertaken due to severe weather conditions and lack of sharks).

Results As a general observation, if a group of divers move towards a group of sharks, the sharks veer away, but if divers move singly towards a group of sharks, and then form themselves into a group of up to five divers the sharks do not display this avoidance behaviour. Over the three trips completed so far, there were no noticeable differences in the reaction of sharks to a diver’s ‘head-on’ approach compared to a ‘tail-on’ approach. All

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approaches where repeated three times on three different occasions, using both semi-closed and open circuit diver systems. A single diver, remaining stationary in the middle of an aggregation of grey nurse sharks did not induce any measurable response from the sharks, irrespective of the gear used (open circuit and semi-closed systems). This aggregation experiment has been conducted once each of the three trips with the diver remaining in the aggregation for 3 - 10 minutes. Diver-shark interactions were also examined at South West Rocks (NSW), although there was no facility for a rebreather versus normal SCUBA comparison (data to be analysed). The results were similar to those generated at Wolf Rock. With three replicates of swimming towards the head of same shark from approximately 6 - 8 metres away the shark did not change course until approximately 75 cm away. The experiments above showed no direct impact of a single diver approaching a shark. However, general observations (not quantified) suggested that the number of sharks in the immediate area diminished over the duration of a dive, presumably in response to diver presence. Summary These preliminary data suggest that the current rules for diver behaviour appear appropriate. Approaching sharks as a ‘formed group of divers’ may result in shark avoidance behaviour that may be avoided by divers approaching either singly or in pairs. It must be noted that the low number of replicates of shark-diver interactions to date do not allow for definitive recommendations. The ability to determine any differences between natural shark abundance and distribution, compared with when divers are present is important to manage any impacts of divers. During 2005, methodology that will more definitively assess the impact of divers has been developed (see below): 7.2.3.1 Possible Future Experimentation Three possible experimental approaches are being developed test whether changes in grey nurse shark behaviour are related to the number and duration of diver presence at aggregation sites.

Methodology & Technique All shark behaviours and shark-diver “interactions” are recorded on digital videotape for subsequent analysis. Distances are calculated by reference to objects of known dimensions or by underwater laser rangefinder. It is intended that population of sharks at Flat and Wolf Rock will be the core experimental groups for this study however as opportunity arises this study will also be repeated at other locations.

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Experiment 1: Explores the possible relationships between the distances of grey nurse sharks from a pair of stationary divers over time.

[Addresses whether sharks activity distance themselves from divers] Experiment 2: Expands on Experiment 1, to explore the effect of larger numbers of divers on shark behaviour. [Addresses whether diver number influences a possible ‘distancing-behaviour’ of sharks]

Experiment 3: Explores the effect of diver presence per se on shark behaviour using a remote operated vehicle.

[Examines how the behaviour of sharks is altered by the arrival of divers in their immediate locality]

Potential Significance This research will provide a scientific basis to managers for protocol development that can be adopted as a ‘Code of Conduct’, or legislation that will remove or minimise disturbance to grey nurse sharks by divers as it is imperative to ensure that divers do not negatively impact on grey nurse shark populations, particularly during critical times such as pupping and mating.

Acknowledgements:

We are indebted to Underwater World, Mooloolaba, Queensland for their generous support for this project in providing crucial assistance in fieldwork at Wolf Rock and access to their marine aquarium housing grey nurse sharks. We also wish to thank QPWS for their continuing commitment to grey nurse shark projects.

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