Why do sea turtles garner such intense interest? The answer is visceral: they are widely loved! A cryptic life cycle spent mostly out of view lends a sense of mystery that makes them special. Yet, these large animals are highly accessible at an extremely vulnerable time, when females emerge on sandy beaches at night to lay eggs, before disappearing again into the oceans. Being nocturnal, they provide us the adventure of going out in the dark on secluded beaches to find them. Plus, the hatchlings are cute, and releasing them into the sea must be one of the most engaging activities that people can do with a protected species.
To mark World Sea Turtle Day on 16 June, we—conservation scientists working across the oceans on this small yet well-studied group of seven species—reflect on their conservation. Sea turtles have lived in the oceans, largely unchanged, for millions of years. They play important roles in their ecosystems, possibly even as ecosystem engineers, and serve as prey for other protected species (Veríssimo et al., Reference Veríssimo, Jones, Chaverri and Meyer2012). They have been a source of sustenance and useful products for people for millennia, and these needs persist (Hancock et al., Reference Hancock, Furtado, Merino, Godley and Nuno2017; Humber et al., Reference Humber, Godley, Nicolas, Raynaud, Pichon and Broderick2017; Delisle et al., Reference Delisle, Kiatkoski Kim, Stoeckl, Watkin Lui and Marsh2018; Sardeshpande & MacMillan, Reference Sardeshpande and MacMillan2019). Consequently, sea turtles are culturally important and the subject of myths and lore. They have also become economically important to many coastal communities through tourism (Waylen et al., Reference Waylen, McGowan and Milner-Gulland2009), although this can affect turtles or their habitats, if not correctly managed (Katselidis et al., Reference Katselidis, Schofield, Stamou, Dimopoulos and Pantis2013).
The complex life history of sea turtles, including their long life span and wide patterns of dispersal, generates multiple conservation challenges, and also draws curiosity and public interest. They serve extensively as flagship species and are useful for harnessing action for marine conservation, whether for coastal protection or in campaigns against single-use plastics. There has been an extensive, and growing, worldwide network of sea turtle conservation organizations for over 50 years. Arguably, there may be more dedicated professionals and volunteers per species than for any other marine animal group.
What are we doing well in sea turtle conservation? After centuries of decline, many sea turtle populations have stabilized or are increasing (Mazaris et al., Reference Mazaris, Schofield, Gkazinou, Almpanidou and Hays2017). Long-term monitoring and protection of nesting sites, in some locations exceeding 50 years, have been central to recovery, understanding trends and determining the importance of previously underestimated aggregations (Kelle et al., Reference Kelle, Gratiot and De Thoisy2009; Delcroix et al., Reference Delcroix, Bédel, Santelli and Girondot2014; Laloë et al., Reference Laloë, Cozens, Renom, Taxonera and Hays2019; Mortimer et al., Reference Mortimer, Esteban, Guzman and Hays2020). This allows researchers and management agencies to understand and mitigate the impacts of anthropogenic activities. Long-term monitoring projects further reinforce the value of protecting nesting and foraging habitats, and promote the engagement of local communities, volunteers, students and tourists, thus benefiting a wide range of stakeholders. Such projects are often showcased in Oryx (Godenger et al., Reference Godgenger, Bréheret, Bal, N'Damité, Girard and Girondot2009; Gaos et al., Reference Gaos, Abreu-Grobois, Alfaro-Shigueto, Amorocho, Arauz and Baquero2010; Garnier et al., Reference Garnier, Hill, Guissamulo, Silva, Witt and Godley2012; Kurz et al., Reference Kurz, Straley and DeGregorio2012; Rivas et al., Reference Rivas, Fernández and Marco2016; Olendo et al., Reference Olendo, Okemwa, Munga, Mulupi, Mwasi and Mohamed2019; Sardeshpande & MacMillan, Reference Sardeshpande and MacMillan2019). Control of predation by natural and introduced mesopredators (Engman et al., Reference Engeman, Addison and Griffin2016; Madden Hof et al., Reference Madden Hof, Shuster, Mclachlan, Mclachlan, Giudice, Limpus and Eguchi2019) and reduction of take through hatcheries, and other forms of ex situ protection (Revuelta et al., Reference Revuelta, León, Broderick, Feliz, Godley and Balbuena2015), have also been prominent.
Legislation in many countries protects turtles from large-scale commercial trade and/or manages local consumption, and CITES, together with in-country support and other international agreements, has halted legal large-scale international trade of sea turtles. Although accidental catch in fishing gear remains a serious threat, various solutions have reduced bycatch in commercial fisheries; e.g. many trawl fisheries now use turtle excluder devices, which allow individuals to escape from nets. Other measures include light-emitting diodes to illuminate gillnets and circle hooks in pelagic longline fisheries.
Sea turtle researchers are often quick to adopt new technologies. Tracking data and genetic analyses have helped reveal the spatial distribution and connectivity of populations across international borders (Metcalfe et al., Reference Metcalfe, Bréheret, Bal, Chauvet, Doherty and Formia2020) and have highlighted key inter-nesting habitats (Hart et al., Reference Hart, Zawada, Sartain and Fujisaki2016). These findings have led to the creation of international collaborative networks, the enhancement of regional conservation actions, and supported the creation of marine protected areas. Additional novel techniques showcased in Oryx range from the use of ultralight aircraft for turtle surveys (Jean et al., Reference Jean, Ciccione, Ballorain, Georges and Bourjea2010) to a radio call-in network for fishers, to support their activities and promote bycatch mitigation (Alfaro-Shiguetto et al., Reference Alfaro-Shigueto, Mangel, Dutton, Seminoff and Godley2012).
What should we do better for sea turtles? Rees et al. (Reference Rees, Alfaro-Shigueto, Barata, Bjorndal, Bolten and Bourjea2016) analysed a decade of publications and surmised that, although variable, progress was being made towards answering key questions identified by an international group of experts in 2010. A worrying finding was, however, that inclusion of social dimensions was still lacking in what is an arena dominated by biologists and ecologists. There has been slow progress to assess cultural, legal, and socioeconomic frameworks, hindering the application of research findings in supporting legislation and management, and in designing robust interventions. This lack of incorporation of social sciences is probably hindering our ability to understand threats and adopt sound management practices with relevant stakeholders. Nevertheless, some progress is being made, and increasing attention to interdisciplinary applications in sea turtle conservation is delivering insightful results (Hancock et al., Reference Hancock, Furtado, Merino, Godley and Nuno2017; Delisle et al., Reference Delisle, Kiatkoski Kim, Stoeckl, Watkin Lui and Marsh2018).
Given the magnitude of effort worldwide, there is great potential to improve our understanding of what works—or does not—in sea turtle conservation. However, monitoring and evaluation remain challenging and are often neglected despite their potential to provide much needed information. For example, assessments of the best incentives or disincentives for affecting compliance with management measures, of how to allocate efforts beneficially for outreach activities, and of how our efforts translate into behavioural change and ecological improvements, would be game changers.
Although over the last 50 years sea turtle conservation has taken a largely protectionist, non-consumptive approach, there is a clear need to adapt our conservation paradigms to be more inclusive and to consider alternative views, including sustainable use (Delisle et al., Reference Delisle, Kiatkoski Kim, Stoeckl, Watkin Lui and Marsh2018, Sardeshpande & MacMillan, Reference Sardeshpande and MacMillan2019). Lack of holistic population demographic data muddies the waters for the potential consumptive use of apparently recovering or recovered populations. Additionally, thresholds of sustainable use, even where exploitation is currently legal, are often poorly identified and lack strong scientific grounding. A key limitation relates to illegal wildlife trade, which often remains an unquantified threat because of the challenge of data collection.
There have been significant efforts to understand the compound, long-lasting effects of commercial fisheries bycatch, including direct and post-release mortality. However, research on bycatch assessments and reduction techniques for artisanal fleets and small-scale fisheries merit continued attention (Nada & Casale, Reference Nada and Casale2011; Mancini et al., Reference Mancini, Koch, Seminoff and Madon2012; Wildermann et al., Reference Wildermann, Sasso, Gredzens and Fuentes2018). As the majority of the life cycle of sea turtles is spent at sea, more needs to be done to monitor and protect all life stages, beyond the more accessible eggs, hatchlings and nesting females.
Climate change remains a pervasive threat to various sea turtle populations around the globe, with much attention focused on impacts related to temperature-dependent sex determination (Hamann et al., Reference Hamann, Fuentes, Ban, Mocellin, Wyneken, Lohmann and Musick2013). Studies of this mainly use indirect proxies that can generate significant error, and more work is needed to quantify this phenomenon more precisely. In addition, we know little about how a changing climate will influence turtle dispersal, growth, diet and other life history parameters. Studies of reproductive success vary across species and locations and this should be addressed for a better understanding of population viability, especially in relation to changes in climate.
Attributing a meaningful conservation status to sea turtles remains a challenge, as conventional categorization systems, such as the IUCN Red List of Threatened Species, are a poor fit at both national and global levels (Seminoff & Shanker, Reference Seminoff and Shanker2008). Current Red List categories can lead to flawed conclusions. For example, a small positive change (e.g. increasing abundance trends) as a result of conservation actions following decades of decline can be perceived as cause for reduced protection. In contrast, ill-used, the system can assign an inaccurate high risk of extinction to a species numbering in the millions per ocean basin. Because the IUCN Red List is the most comprehensive global inventory of species conservation status, and highly regarded by governments and funding bodies, assessments can impact support for conservation (Campbell, Reference Campbell2012). Assessments of subpopulations have alleviated some issues but there remains a clear need to shift from a threatened vs not threatened paradigm to more suitable processes of assessments, such as conservation dependent. Additionally, all current assessments focus exclusively on adult cohorts.
In summary, although our reflections reveal that sea turtle conservation could be further enhanced, the accomplishments of the sea turtle conservation community are cause for optimism. There is more to do, and much will be achieved, in no small part because sea turtles are widely loved!
This Editorial and the Oryx articles cited herein are freely available as a virtual issue of the journal at cambridge.org/core/journals/oryx/virtual-issues.
