Long‐term photo‐id and satellite tracking reveal sex‐biased survival linked to movements in an endangered species

Schofield, Gail; Klaassen, Marcel; Papafitsoros, Kostas; Lilley, Martin K. S.; Katselidis, Kostas A.; Hays, Graeme C.

doi:10.1002/ecy.3027

Cited by 37 publications

(51 citation statements)

References 59 publications

(103 reference statements)

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“…Direct counts of turtles using unmanned autonomous vehicles indicated the presence of up to 90 unique males and 240 unique females in the breeding area in one season (Schofield et al, 2017), falling within the range predicted for previous years based on nest counts by Schofield et al (2015). Tracking of male and female sea turtles from Zakynthos (n = 20 females, Zbinden et al, 2011; n = 55 males and females, Schofield et al, 2020) has demonstrated that females migrate to other areas of the Mediterranean following breeding, whereas around 30% of males remain resident. This information has been corroborated with longterm photo-identification records of over 1000 unique adult male and females, as well as immature turtles (Schofield et al, 2008(Schofield et al, , 2020.…”

Section: Study Site and Speciesmentioning

confidence: 78%

“…The loggerhead sea turtle population of the Mediterranean is currently listed in the category of Least Concern in the International Union for Conservation of Nature (IUCN) Red List of Threatened Species (IUCN, 2020), with its current status considered conservation dependent, as a result of long-term conservation efforts (Casale, 2015). Adult turtles migrate into Laganas Bay to mate as early as March, with most adult males departing in late May, whereas females typically remain to nest from mid-May to early August, at which point they depart for foraging grounds up to 1000 km away (Schofield et al, 2013(Schofield et al, , 2020. Direct counts of turtles using unmanned autonomous vehicles indicated the presence of up to 90 unique males and 240 unique females in the breeding area in one season (Schofield et al, 2017), falling within the range predicted for previous years based on nest counts by Schofield et al (2015).…”

Section: Study Site and Speciesmentioning

confidence: 99%

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Social media reveals consistently disproportionate tourism pressure on a threatened marine vertebrate

Papafitsoros

Panagopoulou²,

Schofield

2020

Animal Conservation

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Establishing how wildlife viewing pressure is distributed across individual animals within a population can inform the management of this activity, and ensure targeted individuals or groups are sufficiently protected. Here, we used social media data to quantify whether tourism pressure varies in a loggerhead sea turtle Caretta caretta population and elucidate the potential implications. Laganas Bay (Zakynthos, Greece) supports both breeding (migratory, and hence transient) and foraging (resident) turtles, with turtle viewing representing a major component of the tourism industry. Social media entries spanning two seasons (April to November, 2018 and 2019) were evaluated, and turtles were identified via photo‐identification. For the 2 years, 1684 and 2105 entries of 139 and 122 unique turtles were obtained from viewings, respectively (boats and underwater combined). However, while residents represented less than one‐third of uniquely identified turtles, they represented 81.9 and 87.9% of all entries. Even when the seasonal breeding population was present (May to July), residents represented more than 60% of entries. Notably, the same small number of residents (<10), mostly males, were consistently viewed in both years; however, different individuals were targeted by boats versus underwater. Thus, turtles appear to remain in the area despite high viewing intensity, possibly indicating low disturbance. However, photo‐identification records revealed a high risk of propeller and boat strike to residents (30%) leading to trauma and mortality. To reduce this threat, we recommend the compulsory use of propeller guards for all boats, compliance with speed regulations and the creation of temporary ‘refuge’ zones for resident animals at viewing hotspots, with these suggestions likely being relevant for other wildlife with similar population dynamics. In conclusion, social media represents a useful tool for monitoring individuals at a population scale, evaluating the pressure under which they are placed, and providing sufficient data to refine wildlife viewing guidelines and/or zoning.

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Section: Study Site and Speciesmentioning

confidence: 78%

Section: Study Site and Speciesmentioning

confidence: 99%

Social media reveals consistently disproportionate tourism pressure on a threatened marine vertebrate

Papafitsoros

Panagopoulou²,

Schofield

2020

Animal Conservation

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“…Using a combination of photo-identification and satellite tracking technology in the Mediterranean, Schofield et al . [ 35 ] found an annual mortality rate of 0.11 for female and 0.27 for male loggerheads. Bentivegna et al .…”

Section: Discussionmentioning

confidence: 99%

Satellite tracking of rehabilitated sea turtles suggests a high rate of short-term survival following release

Robinson

Hyland²,

Beukes

et al. 2021

PLoS ONE

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The rehabilitation of wildlife can contribute directly to the conservation of threatened species by helping to maintain wild populations. This study focused on determining the post-rehabilitation survival and spatial ecology of sea turtles and on comparing the movements of individuals with flipper amputations (amputees) to non-amputee animals. Our aims were to assess whether rehabilitated sea turtles survive after release, to compare and contrast the movement characteristics of the different species of sea turtles we tracked, and to examine whether amputees and non-amputees within species behaved similarly post-release. Twenty-six rehabilitated sea turtles from four species, including hawksbill Eretmochelys imbricata (n = 12), loggerhead Caretta caretta (n = 11), green Chelonia mydas (n = 2), and olive ridley Lepidochelys olivacea (n = 1) sea turtles from the United Arab Emirates were fitted with satellite tags before release. Rehabilitation times ranged from 89 to 817 days (mean 353 ± 237 days). Post-release movements and survival were monitored for 8 to 387 days (mean 155 ± 95 days) through satellite tracking. Tag data suggested that three tracked sea turtles died within four days of release, one after 27 days, and one after 192 days from what are thought to be anthropogenic factors unrelated to their pre-rehabilitation ailments. We then compared habitat use and movement characteristics among the different sea turtle species. Although half of all turtles crossed one or more international boundaries, dispersal varied among species. Loggerhead turtles had a high dispersal, with 80% crossing an international boundary, while hawksbill turtles displayed higher post-release residency, with 66% remaining within UAE territorial waters. Amputee turtles moved similarly to non-amputee animals of the same species. Loggerhead turtles travelled faster (mean ± sd = 15.3 ± 8 km/day) than hawksbill turtles (9 ± 7 km/day). Both amputee and non-amputee sea turtles within a species moved similarly. Our tracking results highlight that rehabilitated sea turtles, including amputees, can successfully survive in the wild following release for up to our ~one-year monitoring time therefore supporting the suitability for release of sea turtles that have recovered from major injuries such as amputations. However, more broadly, the high mortality from anthropogenic factors in the Arabian Gulf region is clearly a serious issue and conservation challenge.

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“…Importantly, whether there are sex-specific differential mortalities across age classes requires further investigation. For instance, male leatherback turtle Dermochelys coriacea hatchlings may exhibit higher fitness than females (Rivas et al 2019), while adult loggerhead females might exhibit higher annual survival rates than males (Schofield et al 2020).…”

Section: Reconstructing Past and Future Nest Temperaturementioning

confidence: 99%

Climate change and marine turtles: recent advances and future directions

Patrício

Hawkes

Monsinjon

et al. 2021

Endang. Species. Res.

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Climate change is a threat to marine turtles that is expected to affect all of their life stages. To guide future research, we conducted a review of the most recent literature on this topic, highlighting knowledge gains and research gaps since a similar previous review in 2009. Most research has been focussed on the terrestrial life history phase, where expected impacts will range from habitat loss and decreased reproductive success to feminization of populations, but changes in reproductive periodicity, shifts in latitudinal ranges, and changes in foraging success are all expected in the marine life history phase. Models have been proposed to improve estimates of primary sex ratios, while technological advances promise a better understanding of how climate can influence different life stages and habitats. We suggest a number of research priorities for an improved understanding of how climate change may impact marine turtles, including: improved estimates of primary sex ratios, assessments of the implications of female-biased sex ratios and reduced male production, assessments of the variability in upper thermal limits of clutches, models of beach sediment movement under sea level rise, and assessments of impacts on foraging grounds. Lastly, we suggest that it is not yet possible to recommend manipulating aspects of turtle nesting ecology, as the evidence base with which to understand the results of such interventions is not robust enough, but that strategies for mitigation of stressors should be helpful, providing they consider the synergistic effects of climate change and other anthropogenic-induced threats to marine turtles, and focus on increasing resilience.

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Long‐term photo‐id and satellite tracking reveal sex‐biased survival linked to movements in an endangered species

Abstract: GC (2020). Long-term photo-id and satellite tracking reveal sex-biased survival linked to movements in an endangered species. Ecology.

Cited by 37 publications

References 59 publications

Social media reveals consistently disproportionate tourism pressure on a threatened marine vertebrate

Social media reveals consistently disproportionate tourism pressure on a threatened marine vertebrate

Satellite tracking of rehabilitated sea turtles suggests a high rate of short-term survival following release

Climate change and marine turtles: recent advances and future directions

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