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The shores of Cape Verde hosts one of the most important nesting populations of the loggerhead turtle Caretta caretta in the world, as well as important feeding grounds for hawksbill Eretmochelys imbricata and green turtles Chelonia mydas. In the past few years, a number of scientific studies have demonstrated the relevance of the waters and beaches of this archipelago for the conservation of these endangered marine megavertebrates. This article aims to bring together the most relevant scientific information published on the subject so far. In addition, we will provide an overview of the current situation of sea turtles in Cape Verde, their conservation status and their importance in an international context.
To actively protect sea turtles on their nesting beaches, it is essential to obtain knowledge about trends in abundance. The way sea turtles live makes it extremely difficult to identify how many individuals there are in a population at any point in time. Due to practical problems, given their entirely marine life with limited visibility and great oceanic dispersal, counting males or juveniles is currently quite difficult and imprecise. Counting females and nests on beaches during the nesting season is the best feasible but still imperfect method, since only an unknown portion of adult females nest every season. It is impossible to know the real number of females in the population by merely counting females and nests in a given year. The number of nesting females can vary greatly from year to year and it is therefore advisable to count them incessantly in subsequent years. Variations in nesting females between years can be independent of general population fluctuations and be due to chance or (unknown) environmental factors. Since the work has to be done at night and the majority of individuals must be marked and recaptured in order to be effective, carrying out censuses of females is complex. Yearly censuses of nests is suggested as the most effective method and the best way to obtain knowledge about the abundance of individuals in a population, their numerical development over time, the conservation status of the population and the effectiveness of conservation measures. The capture frequency of females and poached nests on beaches also requires counting the numbers involved.
On 12 July 2013, an adult female loggerhead sea turtle Caretta caretta with an almost complete longitudinal carapace fracture was observed nesting and returning to sea at João Barrosa beach, Boa Vista, Cape Verde Islands. Due to the evident fracture instability and the likelihood of subsequent system infection development, an intervention was planned to prevent further health decline and eventual death. Beach surveillance was increased to raise recapture possibilities, based on the most likely nesting days for this individual. After 53 days, the animal hauled out again and was allowed to lay eggs before taken away for wound cleaning, stabilization, medication administration and surgery. An orthopaedic surgical intervention for shell repair was performed under field injectable general anaesthesia. The fracture was stabilised in six places by means of four marine resistant stainless steel plates and two orthopaedic wires screwed to the carapace. Finally, all implanted material was covered and protected with epoxy resin to maintain a smooth carapace surface and prevent potential entanglement.
Em paralelo com a protecção activa de tartarugas marinhas nas praias de desova, é fundamental conhecer as tendências das suas abundâncias. A forma de vida das tartarugas marinhas dificulta enormemente o conhecimento do número de indivíduos existentes numa população num determinado momento. Dado o seu ciclo de vida ser totalmente marinho, com escassa visibilidade e grande dispersão oceânica, contar machos ou juvenis é um processo muito complexo e impreciso. É de maior utilidade contar fêmeas e ninhos nas praias durante a temporada de nidificação, apesar do método estar igualmente sujeito a imprecisões visto que apenas uma parte desconhecida de fêmeas adultas desova a cada temporada. É impossível conhecer o número de fêmeas de uma população através da mera contagem de fêmeas nidificantes e ninhos num ano. O número anual de fêmeas nidificantes e ninhos pode variar muito de ano para ano, sendo assim recomendável contá-los de forma contínua, ano após ano. As variações interanuais de fêmeas nidificantes podem ser independentes de flutuações na população e ficarem a dever-se ao acaso ou a factores ambientais desconhecidos. A contagem de fêmeas nidificantes é complexa, pois deve realizar-se de noite e a maioria dos indivíduos deve ser marcada e recapturada para que seja eficaz. Sugere-se a realização de censos contínuos (todos os anos) de ninhos como o método mais eficaz e a melhor forma de conhecer a abundância de tartarugas marinhas numa população, a sua evolução ao longo do tempo, o estado de conservação das populações e a eficácia das medidas de protecção. É também recomendada a monitorização da frequência de captura de fêmeas e de ninhos espoliados nas praias. Em cada ilha ou zona de estudo de Cabo Verde será nomeado um coordenador de investigação responsável pelas actividades e bases de dados. Para além disso, existirão vários técnicos encarregados da protecção, censos e obtenção de informação. Todo o pessoal técnico receberá formação específica antes do início do projecto. Na formação, deverá ser dado um ênfase especial ao manejo de fêmeas e ovos nas praias, à identificação de rastos de ninhos e à correcta recolha e registo de dados.
This is a summary of Elena Abella Pérez's doctoral thesis "Factores ambientales y de manejo que afectan al desarrollo embrionario de la tortuga marina Caretta caretta. Implicaciones en programas de incubación controlada", Estación Biológica de Doñana (CSIC) and Departamento de Biología, Universidad de Las Palmas de Gran Canaria, 29 October 2010.