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Lindsay SA, Fulham M, Caraguel CGB, Gray R. Mitigating disease risk in an endangered pinniped: early hookworm elimination optimizes the growth and health of Australian sea lion pups. Front Vet Sci 2023; 10:1161185. [PMID: 37180065 PMCID: PMC10168540 DOI: 10.3389/fvets.2023.1161185] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/10/2023] [Accepted: 04/04/2023] [Indexed: 05/15/2023] Open
Abstract
The Australian sea lion (Neophoca cinerea) experiences high pup mortality of seasonally alternating severity, partly attributed to endemic hookworm (Uncinaria sanguinis) infection. To further explore health outcomes of early hookworm elimination, a treatment trial was conducted at Seal Bay Conservation Park, South Australia, over consecutive lower and higher mortality breeding seasons (2019, 19.2%; 2020-1; 28.9%). Pups (n = 322) were stratified into two age cohorts (median 14 d and 24 d recruitment ages) and randomly assigned to treated (topical ivermectin 500 μg/kg) or control (untreated) groups. A younger prepatent cohort <14 d old (median 10 d) was identified a posteriori. A seasonally independent growth benefit resulted from hookworm elimination across all age cohorts. The greatest relative improvements (bodyweight + 34.2%, standard length + 42.1%; p ≤ 0.001) occurred in the month post-treatment, in the youngest prepatent cohort. A significant benefit of lesser magnitude (bodyweight + 8.6-11.6%, standard length + 9.5-18.4%; p ≤ 0.033) persisted up to 3 months across all age cohorts - greatest in the youngest pups. Treatment resulted in immediate improvement in hematological measures of health - decreased anemia and inflammation severity (p ≤ 0.012). These results enhance our understanding of host-parasite-environment interactions within the context of hematological ontogenesis, confirm the seasonally independent benefits of hookworm disease intervention, and further inform conservation recommendations for this endangered species.
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Affiliation(s)
- Scott A. Lindsay
- Faculty of Science, Sydney School of Veterinary Science, The University of Sydney, Camperdown, NSW, Australia
- Faculty of Science, School of Animal and Veterinary Sciences, The University of Adelaide, Roseworthy, SA, Australia
| | - Mariel Fulham
- Faculty of Science, Sydney School of Veterinary Science, The University of Sydney, Camperdown, NSW, Australia
| | - Charles G. B. Caraguel
- Faculty of Science, School of Animal and Veterinary Sciences, The University of Adelaide, Roseworthy, SA, Australia
| | - Rachael Gray
- Faculty of Science, Sydney School of Veterinary Science, The University of Sydney, Camperdown, NSW, Australia
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Lindsay SA, Caraguel CG, Gray R. Topical ivermectin is a highly effective seal 'spot-on': A randomised trial of hookworm and lice treatment in the endangered Australian sea lion ( Neophoca cinerea). Int J Parasitol Parasites Wildl 2021; 16:275-284. [PMID: 34877253 PMCID: PMC8633868 DOI: 10.1016/j.ijppaw.2021.11.002] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/29/2021] [Revised: 11/10/2021] [Accepted: 11/10/2021] [Indexed: 12/03/2022]
Abstract
The Australian sea lion (Neophoca cinerea) is an endangered and declining otariid species, with a high rate of pup mortality associated with endemic hookworm (Uncinaria sanguinis) infection a suspected contributor to this decline. Injected ivermectin is an effective treatment for Uncinaria sp. in otariids, with optimal outcomes achieved by the early treatment of pups prior to disease development. This randomised controlled trial evaluated the effectiveness of the novel use of a topical ivermectin formulation against hookworm infection and lice (Antarctophthirus microchir) infestation, in comparison with injected ivermectin. During the 2017 breeding season at Dangerous Reef, South Australia, pups ≤ 70 cm in standard length (≤ 2 weeks of age; n = 85) were randomised to single dose topical (500 μg/kg spot-on; n = 27) or injected (200 μg/kg subcutaneous; n = 29) ivermectin treatment groups, or to an untreated control group (n = 29). Topical ivermectin was highly effective for U. sanguinis elimination, and not significantly different to the injected formulation (estimated effectiveness 96.4% and 96.8%, respectively; P > 0.05). Its application resulted in an 81.6% reduction and 62.7% additional clearance for A. microchir infestation by 15-24 days post-treatment, compared with untreated control pups (also not significantly different to injected ivermectin; 83.1% and 59.4%, respectively; P > 0.05). Treatment with either ivermectin formulation significantly ameliorated increases in inflammatory markers detected in the blood of untreated control pups - peripheral blood eosinophil counts (persisting to 36-41 days post-recruitment P < 0.05) and increased plasma protein concentrations (15-24 days post-recruitment; P < 0.05). Further, an initial short-term decrease in body condition in the control group was not observed in either of the treatment groups. This study demonstrates that topical ivermectin is an effective antiparasitic treatment in N. cinerea. It offers an alternative administration method for ivermectin delivery to a young pup cohort in this species, and an alternative, minimally invasive management tool for species conservation.
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Affiliation(s)
- Scott A. Lindsay
- Sydney School of Veterinary Science, The University of Sydney, Camperdown, New South Wales, Australia
- School of Animal and Veterinary Sciences, The University of Adelaide, Roseworthy, South Australia, Australia
| | - Charles G.B. Caraguel
- School of Animal and Veterinary Sciences, The University of Adelaide, Roseworthy, South Australia, Australia
| | - Rachael Gray
- Sydney School of Veterinary Science, The University of Sydney, Camperdown, New South Wales, Australia
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Shaughnessy PD, Goldsworthy SD. Dispersion of long-nosed fur seals (Arctocephalus forsteri) determined by tagging. AUST J ZOOL 2019. [DOI: 10.1071/zo20032] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
Abstract
Long-nosed fur seals (Arctocephalus forsteri) were tagged as pups in colonies on Kangaroo Island, South Australia in eight consecutive pupping seasons from 1988–89 to 1995–96. Thirty-nine tagged animals were sighted on the southern Australian coast, being 0.89% of those tagged. They were aged from 9 months to 14 years 6 months, with half in their second and third years. Most records (88%) were of animals that moved eastwards. The most distant records were from Sydney in the east (1700 km), south of Tasmania in the south (1240 km) and Head of Bight in the west (700 km). One animal was seen twice, both times on the north coast of Kangaroo Island, once underwater and two years later ashore. Satellite telemetry studies of juvenile A. forsteri from Kangaroo Island showed that they typically forage in pelagic waters ~1000 km further south in association with the subtropical front. The study reported here shows that some animals tagged as pups disperse widely as juveniles around the southern Australian coast. The possibility of genetic interchange between breeding colonies is suggested by sightings of three tagged females aged 4 years and older at non-natal colonies.
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McIntosh RR, Kirkman SP, Thalmann S, Sutherland DR, Mitchell A, Arnould JPY, Salton M, Slip DJ, Dann P, Kirkwood R. Understanding meta-population trends of the Australian fur seal, with insights for adaptive monitoring. PLoS One 2018; 13:e0200253. [PMID: 30183713 PMCID: PMC6124711 DOI: 10.1371/journal.pone.0200253] [Citation(s) in RCA: 24] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/23/2017] [Accepted: 06/22/2018] [Indexed: 11/22/2022] Open
Abstract
Effective ecosystem-based management requires estimates of abundance and population trends of species of interest. Trend analyses are often limited due to sparse or short-term abundance estimates for populations that can be logistically difficult to monitor over time. Therefore it is critical to assess regularly the quality of the metrics in long-term monitoring programs. For a monitoring program to provide meaningful data and remain relevant, it needs to incorporate technological improvements and the changing requirements of stakeholders, while maintaining the integrity of the data. In this paper we critically examine the monitoring program for the Australian fur seal (AFS) Arctocephalus pusillus doriferus as an example of an ad-hoc monitoring program that was co-ordinated across multiple stakeholders as a range-wide census of live pups in the Austral summers of 2002, 2007 and 2013. This 5-yearly census, combined with historic counts at individual sites, successfully tracked increasing population trends as signs of population recovery up to 2007. The 2013 census identified the first reduction in AFS pup numbers (14,248 live pups, -4.2% change per annum since 2007), however we have limited information to understand this change. We analyse the trends at breeding colonies and perform a power analysis to critically examine the reliability of those trends. We then assess the gaps in the monitoring program and discuss how we may transition this surveillance style program to an adaptive monitoring program than can evolve over time and achieve its goals. The census results are used for ecosystem-based modelling for fisheries management and emergency response planning. The ultimate goal for this program is to obtain the data we need with minimal cost, effort and impact on the fur seals. In conclusion we identify the importance of power analyses for interpreting trends, the value of regularly assessing long-term monitoring programs and proper design so that adaptive monitoring principles can be applied.
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Affiliation(s)
- Rebecca R. McIntosh
- Research Department, Phillip Island Nature Parks, Cowes, Victoria, Australia
- * E-mail:
| | - Steve P. Kirkman
- Department of Environmental Affairs, Oceans and Coasts Research, Victoria and Alfred Waterfront, Cape Town, South Africa
- Animal Demography Unit, Department of Biological Sciences, University of Cape Town, Cape Town, South Africa
| | - Sam Thalmann
- Department of Primary Industries, Parks, Water and Environment, Hobart, Tasmania, Australia
| | | | - Anthony Mitchell
- Department of Environment, Land, Water and Planning, Orbost, Victoria, Australia
| | - John P. Y. Arnould
- School of Biological and Chemical Sciences, Deakin University, Burwood, Victoria, Australia
| | - Marcus Salton
- Research Department, Phillip Island Nature Parks, Cowes, Victoria, Australia
- Department of Biological Sciences, Macquarie University, North Ryde, New South Wales, Australia
| | - David J. Slip
- Department of Biological Sciences, Macquarie University, North Ryde, New South Wales, Australia
- Taronga Conservation Society Australia, Mosman, New South Wales, Australia
| | - Peter Dann
- Research Department, Phillip Island Nature Parks, Cowes, Victoria, Australia
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Shaughnessy PD, Bossley M, Nicholls AO. Fur seals and sea lions (family Otariidae) on the breakwaters at Adelaide. AUSTRALIAN MAMMALOGY 2018. [DOI: 10.1071/am17001] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
Abstract
Long-nosed fur seals (Arctocephalus forsteri) and Australian sea lions (Neophoca cinerea) on the breakwaters at the mouth of the Port River estuary at Adelaide’s Outer Harbor were counted from 2004 to 2015. Observed counts were modelled using a generalised linear model. Fur seal numbers have been increasing since 2011; for sea lions there was a small discernible annual trend in counts. Counts of fur seals varied seasonally; most annual maxima were in August or September with modelled peak numbers around 9–11 September. The maximum count of fur seals was 79 in September 2015. For sea lions, the model predicts annual peaks in the period 28 August to 19 September. The maximum count of sea lions was nine in September 2009. The haulout sites on the Outer Harbor breakwaters are easily accessible by boats, including pleasure craft. In particular, the seaward end of the outer breakwater is a popular spot with recreational anglers whose lines are often within a few metres of the seals. We propose that a management plan should be developed involving a study of the effect of boat approaches on seals utilising the Outer Harbor area followed by education coupled with enforcement.
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Marcus AD, Higgins DP, Gray R. Ivermectin treatment of free-ranging endangered Australian sea lion (Neophoca cinerea) pups: effect on hookworm and lice infection status, haematological parameters, growth, and survival. Parasitol Res 2015; 114:2743-55. [DOI: 10.1007/s00436-015-4481-4] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/27/2015] [Accepted: 04/09/2015] [Indexed: 02/03/2023]
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