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Sperm whales (Physeter macrocephalus) are the largest toothed whales and only living member of family Physeteridae. Present survey represents first report on cultivable faecal microbes and gastrointestinal helminths and protozoans infecting free-ranging sperm whales inhabiting Mediterranean Sea waters surrounding Balearic Archipelago, Spain. Twenty-five individual sperm whale scat samples, including one calf, were collected without disturbance of animals during the summer of 2016. Parasitological diagnostic methods, such as sodium acetate acetic formalin (SAF) method, carbol fuchsin-stained faecal smears, Giardia/Cryptosporidium coproantigen ELISAs and an Anisakis-specific PCR were applied for further identification. Five bacterial genera, i.e. Acinetobacter, Clostridium, Enterococcus, Staphylococcus and Streptococcus, and one fungus namely Cladosporium were identified. Parasitological infections included seven different parasite species with some of them bearing anthropozoonotic potential. Thus, four of these parasites were zoonotic, i.e. Anisakis, Balantidium, Diphyllobothriidae gen. sp. and Giardia. Additionally, Zalophotrema curilensis eggs, spirurid-like eggs and Cystoisospora-like oocysts were identified. Molecular characterization identified Anisakis physeteris as the species infecting these whales. This survey provides first records on occurrence of two zoonotic enteropathogenic protozoan parasites (Giardia and Balantidium) and of facultative pathogenic bacteria (Clostridium and Enterococcus) in sperm whales. Presented data should be considered as a baseline study for future monitoring surveys on anthropozoonotic pathogens affecting free-living sperm whale populations and enhance investigations on possible impact on public health as well as on isolated Mediterranean sperm whale subpopulation.

1. Sperm whales in the Mediterranean are classified as 'Endangered' by the IUCN. They are apparently isolated from adjacent Atlantic populations, and subject to anthropogenic pressures including interactions with illegal driftnet fisheries, ship strikes, ingestion of debris and underwater noise. 2. Photo-identification data opportunistically collected from the western Mediterranean basin show that individual sperm whales regularly move in excess of 500km across the western basin, suggesting that this area is occupied by a single population. 3. The best abundance estimate for this region is approximately 400 animals, with confidence intervals between 200 and 1000. 4. Given the mortality levels reported in the literature, this figure suggests that the conservation status of sperm whales in this region is very serious. Immediate priority should be placed both on conducting systematic surveys for abundance estimation and on measures to reduce the mortality associated with driftnet fishing. [ABSTRACT FROM AUTHOR]