Marine wildlife stranding and mortality database annual report 2011 lii. Marine Turtle

Transcription

1 Marine wildlife stranding and mortality database annual report 2011 lii. Marine Turtle

2 Prepared by: Threatened Species Unit, Department of Environment and Heritage Protection The State of Queensland (Department of Environment and Heritage Protection) 2012 Copyright inquiries should be addressed to or the Department of Environment and Heritage Protection, 41 George Street, Brisbane QLD 4000 ISSN X Disclaimer This document has been prepared with all due diligence and care, based on the best available information at the time of publication. The department holds no responsibility for any errors or omissions within this document. Any decisions made by other parties based on this document are solely the responsibility of those parties. Information contained in this document is from a number of sources and, as such, does not necessarily represent government or departmental policy. If you need to access this document in a language other than English, please call the Translating and Interpreting Service (TIS National) on and ask them to telephone Library Services on This publication can be made available in an alternative format (e.g. large print or audiotape) on request for people with vision impairment; phone or <library@ehp.qld.gov.au>. Citation Meager, J.J. and Limpus, C.J. (2012) Marine wildlife stranding and mortality database annual report III. Marine Turtle. Conservation Technical and Data Report 2012 (3):1-46. Cover photo QA Green turtle found in a crab pot in Moreton Bay. StrandNet. ( [accessed: January 2012]). Photo taken by Michael Savige. Reviewers Dr Mark Read, Great Barrier Reef Marine Park Authority Dr Mark Flint, the University of Queensland, Vet-MARTI Acknowledgements The authors would like to thank Jaylene Flint and Michael Savige for constructive comments on the report, and everyone who contributed to the StrandNet program in

3 Foreword The Department of Environment and Heritage Protection (EHP) monitors marine turtle mortality along the Queensland coast via StrandNet, the marine wildlife strandings and mortality database. StrandNet records injured, moribund and dead marine wildlife in Queensland from reports received by the Department of National Parks, Recreation, Sport and Racing (NPRSR), EHP, the Great Barrier Reef Marine Park Authority (GBRMPA) and the Department of Agriculture, Fisheries and Forestry (DAFF), in addition to those received directly from the public and rehabilitation facilities. EHP has managed StrandNet since March 2012, when the Department of Environment and Resource Management (DERM) was divided into five new departments. The previous departmental names are used in the current report, because the data were collected prior to the restructure. This annual report has been published as part of EHP s Conservation Technical and Data Report series. Any request to access these data for research purposes should be made in writing to the StrandNet Coordinator, strand.data@ehp.qld.gov.au. 3

4 Contents Foreword...3 List of acronyms and abbreviations...6 Summary...7 Introduction...8 Methods...9 Results...10 Number and distribution of marine turtles...10 Causes of stranding and mortality...10 Strandings and mortality from natural causes...10 Anthropogenic causes of strandings and mortality...10 Stranded turtles that escaped unaided or were rescued and/or rehabilitated...11 Necropsies...12 Size, sex and life-history stage of stranded/dead marine turtles...12 Marine Protected Areas (MPAs)...12 Gladstone: region of special interest...13 Natural mortalities in the Gladstone region...13 Anthropogenic mortalities in the Gladstone region...13 Activities associated with development: dredging and land reclamation...14 Discussion...15 Spatial and temporal distribution of stranding and mortality records...15 Anthropogenic causes of mortality...16 Table 1. Summary of sick, injured or dead marine turtles by geographical location around the Queensland coast, January 1999 to December Table 2. Summary of marine turtles by geographical location and species in Queensland, 2011 (n = 1793 confirmed records and 34 unconfirmed records)...19 Table 3. Summary of marine turtles by year and identified sources of mortality for Queensland, Table 4. Summary of green turtles (Chelonia mydas) by month and identified sources of mortality/current status for Table 5. Summary of hawksbill turtles (Eretmochyles imbricata) by month and identified sources of mortality/current status for Table 6. Summary of loggerhead turtles (Caretta caretta) by month and identified sources of mortality/current status for Table 7. Summary of olive ridleys (Lepidochelys olivacea) by month and identified sources of mortality/current status for Table 8. Summary of flatback turtles (Natator depressus) by month and identified sources of mortality/current status for Table 9. Summary of Pacific green turtles (Chelonia mydas agassizi) by month and identified sources of mortality/current status for Table 10. Examinations and necropsies of green turtles (Chelonia mydas) in 2011 by carcass condition. Also shown are the number of carcasses with an identifiable cause of death (COD)

5 Table 11. Examinations and necropsies of hawksbill turtles (Eretmochyles imbricata) in 2011 by carcass condition Table 12. Examinations and necropsies of loggerhead turtles (Caretta caretta) in 2011 by carcass condition Table 13. Examinations and necropsies of olive ridley turtles (Lepidochelys olivacea) in 2011 by carcass condition Table 14. Examinations and necropsies of flatback turtles (Natator depressus) in 2011 by carcass condition Table 15. Examinations and necropsies of Pacific green turtles (Chelonia mydas agassizi) in 2011 by carcass condition...32 Table 16. Sex and life-history stage of green turtles, Chelonia mydas Table 17. Sex and life-history stage of hawksbill turtles, Eretmochelys imbricata...33 Table 18. Sex and life-history stage of loggerhead turtles, Caretta caretta Table 19. Sex and life-history stage of flatback turtles, Natator depressus Table 20. Sex and life-history stage of olive ridley turtles, Lepidochelys olivacea...34 Table 21. Sex and life-history stage of Pacific green turtles, Chelonia mydas agassizi Table 22. Marine turtle strandings and mortalities in Marine Parks Figure 1. Monthly cumulative number of marine turtles stranded or dead by year for the Queensland East Coast, from January 1998 to December Figure 2. Monthly cumulative marine turtles by species, Figure 3. Species composition of marine turtle strandings and mortalities in Queensland, 2011, compared to aggregated records between 1996 and Figure 4. Queensland map showing latitudinal and longitudinal grids...39 Figure 5. Distribution of marine turtle strandings and mortalities in Figure 6. Relative distribution of marine turtles in Queensland in 2011, compared to historical data ( )...41 Figure 7. Monthly marine turtle strandings and mortalities in 2011 by latitudinal block (as shown on Figure 4)...42 Figure 8. Length-frequency histogram of green turtles in 2011 compared to aggregated records for green turtles between 1996 and Figure 9. Distribution of marine turtle strandings and mortalities in the Gladstone region in 2011, within (a) the Port of Gladstone (coloured areas are the port limits) and (b) the Gladstone metropolitan area and associated waterways...44 Figure 10. Observed locations of marine turtles killed by vessel interactions (excluding dredges): red symbols. (a) within the Port of Gladstone (grey areas are the port limits) and (b) the Gladstone metropolitan area and associated waterways Figure 11. Annual mortalities of marine turtles from interactions with vessels (impact injuries from hull strike, propeller cuts and skeg damage) since

6 List of acronyms and abbreviations COD Cause of death CCL Curved carapace length Cwlth Commonwealth DEEDI Department of Employment, Economic Development and Innovation DERM Department of Environment and Heritage Protection DAFF Department of Agriculture, Fisheries and Forestry DPA Dugong Protection Area ECIFFF East Coast Inshore Fin Fish Fishery EHP Department of Environment and Heritage Protection GBRMPA Great Barrier Reef Marine Park Authority ICO Interim Conservation Order JCU James Cook University MPA Marine Protected Area NPRSR Department of National Parks, Recreation, Sport and Racing Qld Queensland SCP Queensland Shark Control Program SOCI Species of Conservation Interest UQ University of Queensland UQSVS School of Veterinary Science, University of Queensland 6

7 Summary In 2011, 1793 marine turtles were recorded in StrandNet, Queensland s database of sick, injured, debilitated or dead marine wildlife. This represents the largest annual number recorded by StrandNet in the 16 years for which comprehensive data have been recorded. An additional 34 reports of marine turtles could not be confirmed by a trained expert. Of the 1793 confirmed records, 1408 were mortalities and the remaining 385 were stranded (sick, injured or incapacitated) and escaped unaided, were released after rehabilitation or were released in situ without rehabilitation. The overwhelming majority of records were for green turtles (Chelonia mydas, 73 per cent). Hawksbills (Eretmochyles imbricata, 6 per cent), loggerheads (Caretta caretta, 2 per cent), flatbacks (Natator depressus, 0.3 per cent) and olive ridleys (Lepidochelys olivacea, 0.5 per cent) were also recorded. Additionally, two individuals of the subspecies, Chelonia mydas agassizi were recorded (0.1 per cent). The remaining turtles were unidentified. The region between the Gold Coast and Hervey Bay (28 to 25ºS) accounted for 41 per cent of records (n = 728). The Mackay-Cardwell region (21 S to 18 S) accounted for 30 per cent of records (n = 534). In comparison to previous years, proportionally more records were received for the Gladstone (23 S) and Townsville regions (19 S). Where a cause of death was identifiable (n = 458), more than half (i.e. 55 per cent, n= 254) were found to have died from natural causes. The majority (63 per cent, n= 161) of these turtles were presumed to have died naturally after a protracted period of ill health. As a primarily herbivorous species, it is likely that disturbance of seagrass meadows by the extreme weather events of late 2010 and early 2011 was the main reason for elevated green turtle mortalities in Human activities accounted for 45 per cent (n= 204) of the 458 cases where a cause of death was identifiable. Over half of these anthropogenic mortalities were caused by interactions with vessels. Recreational or commercial fishing (including ghost nets) accounted for 57 mortalities and 35 strandings in 2011, an additional three mortalities and two strandings were attributed to entanglement in ghost nets. Other anthropogenic causes included ingestion of synthetic material (11 mortalities), indigenous hunting (four mortalities), the Queensland Shark Control Program (three mortalities) and dredging (two mortalities). 7

8 Introduction Six species of marine turtles occur in Queensland, five chelonids (loggerhead turtle, Caretta caretta; green turtle Chelonia mydas; hawksbill turtle, Eretmochelys imbricata; olive ridley turtle, Lepidochelys olivacea and the flatback turtle, Natator depressus) and one dermochelyid (leatherback turtle, Dermochelys coriacea). All six species are listed under the Nature Conservation Act 1992 (Qld) and the Environment Protection and Biodiversity Conservation Act 1999 (Cwlth). The Nature Conservation (Wildlife) Regulation 2006 (Qld) classifies the flatback, green and hawksbill turtles as vulnerable, and the loggerhead, leatherback and olive ridley turtles as endangered. Within State and Commonwealth waters, the Marine Parks Act 2004 (Qld) and the Great Barrier Reef Marine Park Act 1975 (Cwlth) provide the capacity to protect marine wildlife within a system of marine parks. State marine parks include the Moreton Bay Marine Park and the Great Sandy Marine Park in southern Queensland. The Great Barrier Reef is protected by both the Great Barrier Reef Marine Park (Commonwealth) and the Great Barrier Reef Coast Marine Park (State), and was rezoned in 2004, greatly increasing protection of marine turtle habitats (Fernandes et al. 2005). Protection from gill netting in Queensland waters is also provided by the two-tiered Dugong Protection Area (DPA) system that was declared under the Fisheries Act 1994 (Qld) by the Fisheries Amendment Regulation (No. 11) 1997 (Qld) and by a series of management arrangements specific for the East Coast Inshore Fin Fish Fishery (ECIFFF). Monitoring the incidence of marine turtles that are sick, injured, incapacitated or dead provides a measure of the effectiveness of the above legislation for maintaining sustainable marine turtle populations. StrandNet is the database where these data are recorded in Queensland. This report presents a summary of the marine turtle data recorded in Data for the marine mammals in 2011 are presented elsewhere (Meager and Limpus 2012; Meager et al. 2012). 8

9 Methods StrandNet is an Oracle database that summarises all records of sick, injured, incapacitated or dead marine wildlife reported to the Department of Environment and Heritage Protection (EHP). EHP has managed StrandNet since March 2012, when the Department of Environment and Resource Management (DERM) was divided into five new departments. The previous departmental names are used in the current report, because the data were collected prior to the restructure. The term stranding is used in the current report to include sick, injured, incapacitated or dead marine turtles that were washed ashore or encountered at sea; in addition to marine turtles which were entangled in fishing nets/synthetic debris or rescued from a situation where they would have died had they not been rescued (Geraci and Loundsbury 1993). In 2011, most marine turtle strandings were reported by staff from DERM or the Great Barrier Reef Marine Park Authority (GBRMPA). Other records were received directly from the public, including records reported via the state-wide stranding telephone hotline ( ). Records of marine turtle mortalities from the Queensland Shark Control Program (SCP) were received from the Department of Employment, Economic Development and Innovation (DEEDI, now the Department of Agriculture, Fisheries and Forestry). Officers from DERM, GBRMPA or DEEDI inspected carcasses that were accessible. Records were lodged in StrandNet by registered users via a web-based interface and each stranding record was assigned a unique identification number, prefixed by Z for marine turtles, unless the animal had been assigned a pre-existing tag number. A record that could not be confirmed as a marine turtle, or where there was insufficient evidence to establish whether the stranding occurred at the time and location reported, was entered into StrandNet as an unconfirmed record (coded as??? ). Additional details that were recorded include the coordinates, location details and date of the report; the sex, life-history stage, size and condition of the animal, and the fate of the animal or carcass. Where available, photos were attached to the record. Records were then verified by a regional Stranding Coordinator. This process was overseen by the statewide Stranding Coordinator to ensure that records were accurate, complete and consistent. The cause of death was established by trained staff examining the carcass and/or photographic records, or by necropsy. Only carcasses that were readily accessible to DERM staff and that were not showing signs of advanced decomposition were necropsied, either by a regional veterinary surgeon, at the University of Queensland s School of Veterinary Science (UQSVS) or James Cook University (JCU). Necropsy records were then uploaded to StrandNet. For those marine turtles not adequately examined, the cause of death was recorded as unknown. It is recognised that StrandNet represents only a proportion of sick, injured or dead marine turtles occurring in Queensland. The number of carcasses or debilitated animals that reach the shoreline depends on factors such as currents, wind and carcass buoyancy, and losses to scavengers (Peltier et al. 2012). This also means that a carcass or debilitated marine turtle may drift substantial distances before stranding. Substantial natural mortality of adult female green turtles has long been a feature of the rookeries at Raine Island and Moulter Cay (Limpus 2009). The majority of these deaths are because of overheating of females that conduct their nesting activities during daylight hours. Data from these turtles are recorded in the EHP Turtle Database and are not reported here, as in earlier StrandNet reports (Haines et al. 2000; Greenland et al. 2003). Similarly, data of marine turtles caught and released alive in the SCP are entered in the EHP Turtle Database and not recorded in StrandNet. Although StrandNet has systematically recorded marine turtle strandings and mortalities from Cairns to the Queensland New South Wales border since 1996, coverage is less comprehensive in sparsely populated areas of the Gulf of Carpentaria, Torres Strait and eastern Cape York Peninsula. It is acknowledged that most hunting of marine turtles is not reported to StrandNet. There are very few records of hunting in the Torres Strait, for example, where a high level of hunting occurs. Illegal hunting (poaching) in Queensland is only generally reported when encountered by DERM or GBRMPA staff. Legal hunting refers to hunting by Aboriginal or Torres Strait Islander people which is allowed under various State or Commonwealth laws, and is reported voluntarily. It is also acknowledged that fisheries bycatch records in StrandNet may be incomplete. Marine turtles can incidentally caught as bycatch in nets or other fisheries gear. Since 2002, it has been a Commonwealth and State obligation for commercial fishers to report interactions with all protected species including marine turtles, in their Species of Conservation Interest (SOCI) logbook. Where available, bycatch records in the Fisheries Queensland annual fisheries updates ( ) were checked against records in StrandNet. 9

10 Results Number and distribution of marine turtles In total, 1827 marine turtle records were received by StrandNet for Of these records, 34 could not be confirmed as marine turtles by DERM staff or a trained expert. These cases are not analysed further. The number of confirmed records in 2011 (n = 1793) represents the largest number recorded by the StrandNet project since comprehensive recording began in 1996 (Figures 1-2). Of the 1793 confirmed records, 385 were presumed to be alive after they: (a) were released in situ, (b) were released after rehabilitation or (c) escaped unaided. Of the 458 turtles where a cause of death was identifiable, 55 per cent (n = 254) were attributed to natural causes, and 45 per cent (n = 204) were attributed to human activities. Five species were recorded: green turtles (Chelonia mydas), hawksbill turtles (Eretmochelys imbricata), loggerhead turtles (Chelonia mydas), flatback turtles (Natator depressus) and olive ridley turtles (Lepidochelys olivacea). Additionally, two records were received for the subspecies, Chelonia mydas agassizi (Pacific green turtle). Green turtles represented 73 per cent of records (n = 1311), hawksbills represented 6 per cent (n = 107) and the remaining species together accounted for 3 per cent of records (Figure 3). The species of 18 per cent of turtles (n = 319) was unidentified. In southern Queensland, the Gold Coast-Hervey Bay region (28 to 25ºS) accounted for 41 per cent of all StrandNet records in 2011 (n = 728) (Tables 1-2; Figures 4-5). The Mackay-Cardwell region (21 S to 18 S) in northern Queensland accounted for 30 per cent of records (or 534 of 1793). Compared to previous years, proportionally more records were received for the Gladstone (23 S) and Townsville (19 S) regions (Figure 6). In contrast, proportionally fewer records were received for the Moreton Bay region (27 S). Temporal trends within each region are summarised by Figure 7. Causes of stranding and mortality The overall identified cause of stranding or mortality of marine turtles is presented in Table 3 and summarised below. Strandings and mortalities by identified cause, species and month are summarised in Tables 4-9. Strandings and mortality from natural causes Natural mortalities of turtles in 2011 (Table 3) can be summarised as follows: 233 died of disease or ill health: o Presumed protracted ill health: 161 o Unidentified disease: 46 o Spirorchiidiasis (spirorchiid parasite infection ): 10 o Blocked gut (not attributable to any particular cause): 8 o Anaemia: 2 o Septicaemia: 2 o Gut parasites: 1 o Gut trauma: 1 o Liver malfunction: 1 o Pneumonia: 1 Predation: 7 cases o Shark: 4 o Crocodile: 2 o Unidentified: 1 Trapped by a natural event: 2 Unidentified natural causes: 12 cases Anthropogenic causes of strandings and mortality Indigenous hunting Only four cases of indigenous hunting of green turtles were reported to StrandNet in All of these cases were believed to be legal hunting by Traditional Owners. 10

11 Interactions with vessels In total, 126 marine turtles were recorded as killed or injured by vessels in 2011, this included propeller cuts, skeg damage and impact injuries from hull strikes. Of these 126 cases: 116 were mortalities. 10 were injured turtles which were either rehabilitated or left to natural processes. Most were recorded in the Moreton Bay (n = 51), Gladstone (n = 36) and Townsville (n = 13) latitudinal regions. Seven were recorded in the Sunshine Coast region, four were recorded in the Hervey Bay/Great Sandy Marine Park region, two were recorded in the Hinchinbrook Island area (18ºS) and three were recorded in the Mackay-Bowen Region (20 to 22ºS). Green turtles accounted for 85 per cent of mortalities attributed to vessel interactions. Vessel interactions occurred in all months, but tended to be more frequent in late winter/early spring, with 41 per cent of records occurring between August and October. Fisheries-related activities (excluding vessel interactions) 32 turtles were recorded as entangled in nets or injured on board a vessel: o 13 of these turtles were released alive, o 19 of these cases were mortalities. Five turtles were recorded as entangled in ghost nets: o two of these turtles were released alive, o three turtles were recorded to have died because of ghost-net entanglement. 37 turtles were recorded as entangled or caught in crab pots or associated gear: o 13 of these turtles were released alive o 24 of these cases were mortalities: 15 were caught inside pots, nine were entangled in float lines. 23 turtles were recorded as entangled in fishing line, entangled in ropes associated with fishing, or killed or injured by other activities associated with fishing (other than those listed above): o 9 turtles were released alive o 14 of these cases were mortalities: nine were entangled in fishing line, one had ingested a fishing hook, four were entangled in rope presumed to be associated with fishing. Queensland Shark Control Program The Shark Control Program (SCP) accounted for three marine turtle deaths in 2011: o two records were received from DEEDI for turtles entangled in nets on the Sunshine Coast (one loggerhead and one green turtle), o one record of a green turtle entangled in a SCP net in the Cairns region was received from a life guard. Ingestion of synthetic material 11 turtles were confirmed (n = 8) or suspected (n = 3) to have died after ingestion of synthetic material: these records occurred between Cairns and Moreton Bay, and from February to December. Other mortalities associated with human activities two mortalities were attributed to dredging one turtle was believed to have been run over by a vehicle while basking ashore. Stranded turtles that escaped unaided or were rescued and/or rehabilitated Green turtles: o 94 rescued, o 124 released after rehabilitation, o 31 escaped unaided. Hawksbill turtles: 11

12 o five rescued, o nine released after rehabilitation, o one escaped unaided. Loggerhead turtles: o three rescued, o five released after rehabilitation, o three escaped unaided. Olive ridley turtles: o one rescued, o two released after rehabilitation. Flatback turtles: o one rescued, o two released after rehabilitation, o two escaped unaided. The species was not recorded for two turtles that were rehabilitated. Most turtle rehabilitation occurred in south-east Queensland between Moreton Bay and the Sunshine Coast, where 62 turtles were recorded to have been rehabilitated and released in The Townsville region recorded 30 successful rehabilitations, the Gladstone region recorded 14 successful rehabilitations, 13 were recorded in the Hervey Bay/Great Sandy Marine Park region, and 12 were recorded in the Cairns/Innisfail region. All other regions accounted for the remaining 12 turtles. Necropsies In total, 183 green turtles (Table 10), 22 hawksbills (Table 11), five loggerheads (Table 12), three olive ridleys (Table 13), one flatback (Table 14) and one Pacific green turtle (Table 15) were necropsied in Histopathology samples were analysed in 36 marine turtles. Size, sex and life-history stage of stranded/dead marine turtles Green turtles: Most green turtles were juveniles [Table 16, see also the cm curved carapace length (CCL) cohort on Figure 8]. Proportionally more juvenile green turtles were recorded in 2011 than during an average year in the StrandNet program (i.e. compared to the overall size-frequency distribution from 1996 to 2010, Figure 8). The opposite was true for small adults/large subadults ( CCL), which were proportionally less frequent in 2011 than in previous years (Figure 8). Adult females were recorded more frequently than adult males. There was close to twice the number of adult females (n = 120) than adult males (n = 65) in Hawksbill turtles: Loggerheads: Other species: Of the 104 turtles where life-history stage was determined, 98 per cent were juveniles. No hatchlings or post-hatchlings were recorded (Table 17). More than half were adult sized (53 per cent of 38 loggerheads where size data were recorded, Table 18): o 11 adults were males and one was a female, o Sex was undetermined for the remaining eight turtles. Sex and life-history stages of species with fewer than ten records are summarised by Tables Marine Protected Areas (MPAs) Strandings and mortalities within each MPA are summarised in Table 22. Overall, the Great Barrier Marine Park region (Great Barrier Reef Coast Marine Park and Great Barrier Reef Marine Park) accounted for 28 per cent of records in The Great Sandy Marine Park accounted for 10 per cent of records and the Morton Bay Marine Park accounted for 21 per cent of records. 12

13 Gladstone: region of special interest Gladstone was the focus of considerable media attention in 2011 because of elevated rates of strandings and mortalities, and concerns from the public in relation to possible impacts of the development activities of the Port of Gladstone on marine wildlife. For consistency with previous reports, the Gladstone Region is defined as the 23ºS block which includes the area from Rodds Bay in the south to north of Yeppoon (Figure 4), but the locations and species of marine turtle strandings and mortalities within this region are given in Figure 9. In total, 323 marine turtles were recorded in StrandNet for the Gladstone region in 2011, compared to 60 records in 2010, 51 records in 2009 and 55 records in This represents a disproportionate increase in the relative number of records for the Gladstone region in 2011 compared to most other regions in Queensland (Figure 6). A similar temporal trend was evident for the Townsville region (i.e. the 19ºS latitudinal block). Of the 256 mortalities of turtles in the Gladstone region in 2011, 55 were attributed to anthropogenic activities and 43 were attributed to natural causes. This compares to seven anthropogenic and five natural mortalities in 2010, and four anthropogenic and two natural mortalities in Natural mortalities in the Gladstone region Of 43 natural mortalities in the Gladstone region in 2011: 20 deaths (46 per cent) were attributed to unknown disease (six confirmed and 14 suspected), 17 deaths (39 per cent) were attributed to protracted ill health (three confirmed and 14 suspected), four deaths were attributed to unidentified natural causes (two confirmed and two suspected), two died while ashore to nest (one was impaled on log and the other died of presumed natural causes). Anthropogenic mortalities in the Gladstone region Suspected fisheries interactions in the Boyne River estuary For the purposes of this report, the Boyne River estuary was defined by a polygon that extended for 1 km from the estuary. In total, 51 marine turtle records were received for the Boyne River estuary in 2011: 49 green turtles, one hawksbill and one unidentified turtle. Of these, 37 died and 14 escaped unaided, were released after rehabilitation or were released in situ without rehabilitation. Other than cases attributed to net entanglement, other sources of mortality were identified: vessel strikes (two suspected), fishing line entanglement (two confirmed), blunt-force trauma (one suspected), protracted ill health (two suspected and one confirmed) and unidentified natural disease (one suspected and one confirmed). Background of incident and management response: A sudden spike in green turtle mortalities occurred in April Data available at the time suggested that 20 green turtles died at the mouth of the Boyne River estuary between 10 and 27 April. All turtles appeared to be in healthy condition with no obvious signs of cause of death. This coincided with an increase in commercial netting in response to ~30,000 barramundi washing over the Awooga Dam spillway following heavy rainfall, and reports of fishers capturing and releasing turtles in the area from the public and staff from the Queensland Parks and Wildlife Service and the Queensland Boating and Fisheries Patrol. On May 1, an Interim Conservation Order (ICO, Part 6, Section 102, Nature Conservation Act 1992 Qld) was enacted to prohibit commercial net fishing in the Boyne River east of the Awoonga Dam spillway seaward to a 1 km radius from the fisheries board on the north bank of the Boyne River on Boyne Island. This was in place for 60 days while management plans were implemented. No marine-turtle mortalities were recorded in the Boyne River estuary in the following month. While the ICO was in place, o nine mortalities were recorded (7-30 June) none of these were attributed to commercial fishing activities, one mortality was attributed to fishing line entanglement and two were attributed to unidentified disease. Subsequently, rangers attended the recovery of set nets in the area and released two green turtles from nets alive in July. A third green turtle died after becoming entangled in set net in August. 13

14 Interactions between turtles and vessels In total, there were 36 mortalities that were either suspected or confirmed to have been the result of vessel interactions (Figure 10). This represents a sharp increase in the annual rate of vessel interactions in the area (Figure 11). Five turtles in the region had vessel-related injuries (propeller damage or blunt-force fractures) and were released alive. StrandNet does not distinguish between turtles that are killed by commercial or recreational vessels. Activities associated with development: dredging and land reclamation Two turtles were recorded to have been killed by dredging operations in the Gladstone region during 2011: one juvenile green turtle (Z228242, 13/12/2011) and one juvenile olive ridley (Z228709, 30/08/2011). Six turtles were trapped inside bundwalls during land reclamation and were rescued and released back into their natural habitat. 14

15 Discussion Strandings and mortalities of marine turtles in 2011 were the highest recorded in Queensland since the commencement of a comprehensive strandings program in Close to twice the number of confirmed records of marine turtle strandings and mortalities were received in 2011 (n = 1793), compared to the previous record year, 2009 (n = 932). As in previous years (Haines et al. 2000; Haines and Limpus 2001; Greenland et al. 2003; Greenland and Limpus 2004; Greenland et al. 2004; Greenland et al. 2005; Biddle and Limpus 2011), the overwhelming majority were green turtles, which represent the most abundant marine turtle species in coastal waters of eastern Australia (Limpus 2007). Natural processes such as disease, predation and starvation were associated with the deaths of 56 per cent of the 453 turtles where a cause of death was identifiable. Most (92 per cent) of these natural mortalities were because of presumed protracted ill health, as indicated by poor to very poor body condition and/or by internal examination during a necropsy. Human activities accounted for 44 per cent of the 453 cases where a cause of death was identifiable, and over half of these anthropogenic mortalities were caused by interactions with vessels. The most plausible explanation for the high rate of strandings and mortalities of green turtles in 2011 was that the extreme weather events (floods and a cyclone) of late 2010 and early 2011 impacted on their seagrass foraging areas. This interpretation is based on three observations: (1) Most mortalities were attributed to protracted ill health/poor body condition in green turtles, a species that primarily forages on seagrass (Limpus 2009 and references therein). (2) Seagrass pastures in Queensland were impacted by elevated rainfall, flooding and a cyclone during summer 2010 to (3) Elevated rates of turtle mortalities have followed similar weather events in the past (Marsh and Kwan 2008; C.J. Limpus, unpublished data). A strong La Niña event in 2010 resulted in elevated rainfall across the Queensland coast and severe floods in southern and central Queensland from December 2010-January Seagrasses within Moreton and Hervey Bay were impacted upon by flooding and/or high levels of river discharge in the Burnett, Mary and Brisbane Rivers (DERM data, unpublished). Elevated river discharge results in increased export of nutrients and suspended sediments into coastal waters, which impacts on seagrasses by reducing the availability of photosynthetic light, and possibly, by modifying sediment characteristics (Campbell and McKenzie 2004). Shortly afterwards, in February 2011, Cyclone Yasi crossed the northern Queensland coast near Cardwell and resulted in extensive seagrass loss in the Missionary Bay/Hinchinbrook area (near Cardwell) and in Cleveland Bay (off Townsville). Spatial and temporal distribution of stranding and mortality records Even in cases where the cause of death is not identifiable, much can be learnt from analysing spatial and temporal clustering of stranding records (Norman et al. 2012). Compared to the spatial distribution of records in an average year, proportionally more records were received for the Gladstone and Townsville regions in The number of records in each of these regions exceeded the previous maximum number of records in a given year. In both regions, the number of records in 2011 was more than three times the previous annual maximum, which occurred in 2010 for Townsville and in 2003 for Gladstone. In contrast, the number of records received in 2011 for the Moreton Bay region was 12 per cent less than the previous annual maximum, which occurred in In the 16 years for which quantitative data have been collected (since 1996), the Moreton Bay region has always had the highest number of annual records in Queensland. Whether this is because of higher stranding and mortality rates and/or higher reporting rates is not known. In the Gladstone region, the number of marine turtles recorded in StrandNet in 2011 represented a more than fivefold increase from The data suggest that the main reasons for this were likely to be because of: (1) suspected fisheries-related interactions in the Boyne estuary during April 2011, (2) an overall elevated rate of strandings and mortalities of marine turtles across eastern Queensland in relation to the extreme weather events of , and (3) an increase in vessel activity associated with development in the Port of Gladstone. In the Townsville region, 308 marine turtles were recorded in 2011, again representing a considerable increase from 2010 (n = 96), and from previous years (e.g. 44 records in 2009; 35 records in 2008). Of the 238 turtle mortalities in the region in 2011, the majority of identifiable cases (i.e. 77 of 95 cases) were 15

16 attributed to natural causes. Eighteen mortalities were attributed to anthropogenic activities. The cause of death in the remaining cases was unidentified. The monthly number of marine turtles peaked in mid-late winter in most regions, and continued to be elevated until the end of the year (Figure 7). Historical trends indicate that elevated mortality and stranding rates of marine turtles generally occur five to eight months after significant loss of seagrass (C. Limpus, unpublished data). Additionally, stranding and mortality rates of marine turtles typically increase during late winter, possibly because of winter temperatures and/or seasonal changes in seagrass production. Anthropogenic causes of mortality Overall, vessel interactions were the main cause of anthropogenic mortality to marine turtles in Interactions largely caused hull/skeg fractures and propeller cuts to carapaces. Injuries presumed to have been associated with large vessels, based on the depth, width and spacing of propeller cuts, were observed predominantly in the Gladstone and Moreton Bay areas, but this information was not recorded systematically in StrandNet. It was also difficult to determine exactly where mortalities from vessel interactions occurred because turtles can float away from the site of impact, and this drift is controlled by both surface currents and wind. Compared to 2010, increased rates of turtle-vessel interactions were evident across Queensland, but there was a sharp increase in the Moreton Bay and Gladstone regions. The number of vessel strikes in the Gladstone area was far in excess of previous records in the area. This was likely to be because of activities associated with developing the Port of Gladstone, and an increase in vessel traffic associated with the accompanying increase in population. Accidental mortalities from fishing or fishing-related activities continue to be a major a source of anthropogenic mortality for marine turtles in Queensland. Of fisheries-related activities, crab pots and float lines associated with crab pots accounted for most records. Evaluating the impact of fisheries-related activities on a stock-by-stock basis depends on having accurate records of bycatch and a comprehensive vessel observer program. Since 2002, it has been a Commonwealth and State obligation for commercial fishers to report interactions with all protected species including marine turtles in their Species of Conservation Interest (SOCI) logbook. At the time of writing, the Fisheries Queensland Annual Status reports were not available for An important point is that the likelihood of identifying net entanglement as the cause of death is less than that of vessel collisions, because the latter human activity usually produces very obvious external damage to the carapace (i.e. cuts from propellers/skegs or blunt-force fractures), whereas the former is much harder to identify externally and can only be confirmed when the turtle is observed to be caught in the net or in a detailed necropsy. Further, natural processes may make turtles more susceptible to human impacts or vice versa. For example, it is possible that turtles range further in search of food when food is limited, and thereby increase the likelihood that they encounter nets or vessels, or that poor condition makes them less able to escape net entanglement or evade vessels. Only four records of indigenous hunting were received in This is less than in other years in the StrandNet program. However, not all incidents are recorded to StrandNet and hunting continues to be arguably the largest source of uncertainty in estimating anthropogenic mortality of marine turtles in Queensland. 16

17 References Biddle, T.M. and Limpus, C.J. (2011) Marine wildlife stranding and mortality database annual report III. Marine turtles. Conservation Technical and Data Report 2010, Campbell, S.J. and McKenzie, L.J. (2004) Flood related loss and recovery of intertidal seagrass meadows in southern Queensland, Australia. Estuarine Coastal and Shelf Science 60, Fernandes, L., Day, J.O.N., Lewis, A., Slegers, S., Kerrigan, B., Breen, D.A.N., Cameron, D., Jago, B., Hall, J., Lowe, D., Innes, J., Tanzer, J., Chadwick, V., Thompson, L., Gorman, K., Simmons, M., Barnett, B., Sampson, K., De'Ath, G., Mapstone, B., Marsh, H., Possingham, H., Ball, I.A.N., Ward, T., Dobbs, K., Aumend, J., Slater, D.E.B. and Stapleton, K. (2005) Establishing representative no-take areas in the great barrier reef: Large-scale implementation of theory on marine protected areas. Conservation Biology 19, Geraci, J.R. and Loundsbury, V.J. (1993) Marine mammals ashore: a field guide for strandings. Texas A&M Sea Grant Publications, Galveston Texas. Greenland, J.A. and Limpus, C.J. (2004) Marine wildlife stranding and mortality database annual report III. Marine turtles. Conservation Technical and Data Report 2004, Greenland, J.A., Limpus, C.J. and Currie, K.J. (2003) Marine wildlife stranding and mortality database annual report III. Marine turtles. Conservation Technical and Data Report 2002, Greenland, J.A., Limpus, C.J. and Brieze, I. (2005) Marine wildlife stranding and mortality database annual report III. Marine turtles. Conservation Technical and Data Report 2002, Greenland, J.A., Limpus, C.J., Currie, K.J. and Brieze, I. (2004) Marine wildlife stranding and mortality database annual report III. Marine turtles. Conservation Technical and Data Report 2003, Haines, J.A. and Limpus, C.J. (2001) Marine wildlife stranding and mortality database annual report III. Marine turtles. Conservation Technical and Data Report 2000, Haines, J.E., Limpus, C.J. and Flakus, S. (2000) Marine wildlife stranding and mortality database annual report III. Marine turtles. Conservation Technical and Data Report 2000, Limpus, C.J. (2007) Marine turtles. In: Tzioumis, V., Keable, S. (Eds.), Description of key species groups in the East Marine Region. Australian Museum, pp. Limpus, C.J. (2009) A biological review of Australian marine turtle species. Queensland Environmental Protection Agency, Brisbane, pp Marsh, H. and Kwan, D. (2008) Temporal variability in the life history and reproductive biology of female dugongs in Torres Strait: The likely role of sea grass dieback. Continental Shelf Research 28, Meager, J.J. and Limpus, C.J. (2012) Marine wildlife stranding and mortality database annual report I. Dugong. Conservation Technical and Data Report 2012, Meager, J.J., Winter, K.M., Biddle, T.M. and Limpus, C.J. (2012) Marine wildlife stranding and mortality database annual report II. Cetacean and Pinniped. Conservation Technical and Data Report 2012, Norman, S.A., Huggins, J., Carpenter, T.E., Case, J.T., Lambourn, D.M., Rice, J., Calambokidis, J., Gaydos, J.K., Hanson, M.B., Duffield, D.A., Dubpernell, S., Berta, S. and Klope, M. (2012) The application of GIS and spatiotemporal analyses to investigations of unusual marine mammal strandings and mortality events. Marine Mammal Science 28,

18 Table 1. Summary of sick, injured or dead marine turtles by geographical location around the Queensland coast, January 1999 to December Year GOC Qld (east coast in 1 o latitude blocks) Total 1999* * * * * 6+ 11? 3 5+1? ? 8+1? ? 212+5? ? 2004* ? ? 59+2? ? ? 2005* ? 6+ 2? ? ? ? ? 2006* ? 24+ 7? ? 69+1? ? ? 2007* ? 11 +1? 39 +2? 23 +4? 25 +1? ? ? ? ? 2008* ? 26+ 1? ? 69+ 1? ? ? 2009* ? ? ? 2010* ? 16+1? ? 147+3? 37+2? ? 73+5? ? ? ? 35+ 1? 66+ 1? ? 76+2? r + 1? ? 5+1? ? * data taken from Biddle and Limpus (2011),? unconfirmed marine turtle report (not validated by an expert); GOC, Gulf of Carpentaria. See Figure 4 for location of latitudinal blocks. r two of these records were turtles that had re-stranded (i.e. were recorded in an earlier instance). 18

19 Table 2. Summary of marine turtles by geographical location and species in Queensland, 2011 (n = 1793 confirmed records and 34 unconfirmed records). Species GOC Qld (east coast in 1 o latitude blocks) Total Chelonia mydas Eretmochyles imbricata ? ? Caretta caretta Natator depressus Lepidochelys olivacea Chelonia mydas agassizi Unidentified ? 5+1? 19+1? 64+16? 31+2? ? ? 1+1? 352 Total ? 35+1? 66+1? ? 76+2? r +1? ? 5+1? ?? unconfirmed marine turtle report (not validated by an expert); r two of the records were turtles that stranded a second time. 19

20 Table 3. Summary of marine turtles by year and identified sources of mortality for Queensland, Cause of Year stranding or mortality 2000* 2001* 2002* 2003* 2004* 2005* 2006* 2007* 2008* 2009* 2010* 2011 Natural mortality Disease and ill health R 233 Predation Other R 2 R 2+3 R 1 14 Anthropogenic Boat strike/ Fractures R R Netting/ on deck damage R 3+1 R 2 4 R 1 R R Ghost nets R 11+1 R 22+1 R R 3+2 R Dredging Shark Control Program Rope entangl/ fishing line/ other fisheries Entanglement in float line/ crab pot R R 4+7 R 6+6 R 10+6 R 7+4 R 6+8 R 15+9 R R 24+2 R R 36+11R R R R Ingestion of foreign mat R 13+4 R 9+2 R 9+3 R 4+2 R 11 Nonpermitted hunting Permitted indigenous hunting Undetermined hunting Other/ undetermined R 6+7 R R 7+7 R Undetermined R 74 R 113 R 112 R 147 R +108 R 331 R Total R 79 R 87 R 137 R 37?+143 R 143 R +204 R * data taken from Biddle and Limpus,? unconfirmed marine turtle report (not validated by an expert). R Rescued or released via natural escape. 20

21 Table 4. Summary of green turtles (Chelonia mydas) by month and identified sources of mortality/current status for Within each column, the italicised numbers to the right denote the total number of suspected cases in each category, the numbers to the left denote cases that have been confirmed (i.e. strong supporting evidence). r a turtle re-stranded. Month Total for month Disease/ ill health Natural causes Human related causes Predation Other Boat strike/ fractures Nets (fishing) Ghost nets Dredging Qld shark control Entangle. Entangle. float line crab pot Ingestion of synthetic Permitted hunting program material rope / fish line / other fisheries activities Other / un determined Rescued or Released Unidentified causes Assumed Rescued Rescue via Rehabilitation Assumed Rescue via Rehab. Release via natural escape Assumed Release via natural escape January February March April May June July August September October r November December r Total Undetermined 21

22 Table 5. Summary of hawksbill turtles (Eretmochyles imbricata) by month and identified sources of mortality/current status for Within each column, the italicised numbers to the right denote the total number of suspected cases in each category, the numbers to the left denote cases that have been confirmed (i.e. strong supporting evidence). Month Total for month Disease/ ill health Natural causes Human related causes Unidentified causes Predation Other Boat strike/ fractures Nets (fishing) Ghost nets Dredging Qld shark control program Entangle. rope / fish line Entangle. float line crab pot Hunting Other / un determined January February 1 1 March 0 April 1 1 May June July August September October November December Total Ingestion of synthetic material Undetermined Rescued or Released Assumed Rescued Rescue via Rehabilitation Assumed Rescue via Rehab. Release via natural escape Assumed Release via natural escape 22