Disease risk analysis in sea turtles: A baseline study to inform conservation efforts

The impact of a range of different threats has resulted in the listing of six out of seven sea turtle species on the IUCN Red List of endangered species. Disease risk analysis (DRA) tools are designed to provide objective, repeatable and documented assessment of the disease risks for a population and measures to reduce these risks through management options. To the best of our knowledge, DRAs have not previously been published for sea turtles, although disease is reported to contribute to sea turtle population decline. Here, a comprehensive list of health hazards is provided for all seven species of sea turtles. The possible risk these hazards pose to the health of sea turtles were assessed and “One Health” aspects of interacting with sea turtles were also investigated. The risk assessment was undertaken in collaboration with more than 30 experts in the field including veterinarians, microbiologists, social scientists, epidemiologists and stakeholders, in the form of two international workshops and one local workshop. The general finding of the DRA was the distinct lack of knowledge regarding a link between the presence of pathogens and diseases manifestation in sea turtles. A higher rate of disease in immunocompromised individuals was repeatedly reported and a possible link between immunosuppression and environmental contaminants as a result of anthropogenic influences was suggested. Society based conservation initiatives and as a result the cultural and social aspect of interacting with sea turtles appeared to need more attention and research. A risk management workshop was carried out to acquire the insights of local policy makers about management options for the risks relevant to Queensland and the options were evaluated considering their feasibility and effectiveness. The sea turtle DRA presented here, is a structured guide for future risk assessments to be used in specific scenarios such as translocation and head-starting programs.

Introduction section. The authors highlight the difficulty of studying marine species such as sea turtles and their diseases. The authors should comment briefly on the potential of current and future advances to better facilitate such research, for example comment on the potential of emerging eDNA technologies to aid somewhat with the detection of sea turtles and their pathogens/parasites in the marine environment 1-4 .   Table 3. Gram positive bacteria 'Unfortunately there was not enough time to go through this list.'. While I appreciate that there may have been limited time at the workshops, could the authors arrange a virtual meeting (e.g. Zoom) or online poll of the relevant participants to go through and rank this list? I would recommend this, and the inclusion of the top 3 ranked gram positive bacteria in this table.
Also   Table 5, Section C. Although occurring after the time of the workshops, it would be worth noting here the extremely detrimental effect the current covid19 pandemic is having on the viability of ecotourism models. There is already a lot of anecdotal evidence in the media that the decline in travel is severely affecting programmes that are primarily supported through ecotourism.
Sections 3.4.2.1. and 3.4.2.2. might be better suited to the appendix/supplemental material. Although present as local case studies, they do not add as much to the overall global picture, therefore I would suggest moving them.

Appendix 7 page 53: 'Surgery is done in some areas but after rehabilitation and release, tumour regrowth may happen and low probability of success is reported in Southeastern parts of USA'
This sentence is misleading. Probability of success is proportional to severity of disease. For example, in Florida 44% of FP tumor score 1 sea turtles are successfully rehabilitated and released (Stage 2: 22%, and Stage 3: 6.4%) 10 . Many turtles stranding with FP have comorbidities (emaciation, entanglement, boat-strikes etc.), and these figures do not differentiate between when non-successful rehabilitation of FP-afflicted turtles was due to FP or these other non-FP factors. Furthermore, the ability to treat and rehabilitate FP-afflicted sea turtles continues to be refined, for example the introduction of laser surgery, and a number of studies demonstrating effectiveness of a variety of human anti-cancer therapeutics for the treatment of FP. The figures reported above cover the period from 2006-2016 and do not necessarily take account of the latest advances or their effect on rehabilitation success. Therefore, this sentence should be altered to more accurately reflect the success or otherwise of rehab, please change to: 'Surgery is conducted in some areas, in some cases after rehabilitation and release, tumour regrowth may occur and there is a varying probability of rehabilitation success reported in Southeastern parts of the USA'.
While comprehensive assessment is lacking, sea turtles previously rehabilitated for FP have subsequently been identified nesting (many years later). Conversely some rehabilitated turtles have re-stranded with FP regrowth. Appendix 7 page 54: 'The only sea turtle herpes virus successfully isolated in cell culture'. Do you mean that in this study when samples were used in cell culture that this was the only herpesvirus isolated, or that this is the only sea turtle herpesvirus ever isolated from cell culture? Please clarify. If the latter, ChHV5 has recently also been cultured using a cell culture model 11 .