A female Risso’s dolphin (Grampus griseus) carcass was found stranded in fresh condition at Jeju Island of the Republic of Korea on February 18, 2018. Body surface lacerations, gross pathology and histology of the lung indicated the cause of death as drowning by fishing gear entanglement. The dolphin was a five-year-old mature female having ovaries with follicles and a corpus albican. This is the lowest recorded age thus far of a Risso’s dolphin with active ovaries. The stomach was filled with Japanese flying squid and based on their distribution, it is believed that the dolphin was foraging in the South Sea, which had not been known as their habitat before. Intestinal microbiome analysis revealed that the bacterial community predominantly comprised phylum Proteobacteria (92.8 per cent). To our knowledge, this is the first microbiome analysis and the first official necropsy report of stranding in Jeju Island of the Risso’s dolphin.
- fishing gear entanglement
- follicular maturation
- Grampus griseus
- sexual maturity age
- South sea
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BYK and SCP contributed equally.
Contributors SWK and SJH contributed equally to this paper. Correspondence: BYK and SCP. SWK and SJH conceived the original idea. BYK provided the Risso’s dolphin carcass. SWK, SJH, YRL and BYK carried out the field necropsy and sampling together. SWK and SJH did a gross pathological analysis and squid habitat data searching. SWK did the DNA sequencing for species confirmation and differential diagnosis list check-up, histopathological analysis and histological analysis of ovaries. SJH did microbiome analysis and related document investigation. SWK and SJH wrote the manuscript with help from SCP. BYK and SCP supervised the whole project.
Funding The authors have not declared a specific grant for this research from any funding agency in the public, commercial or not-for-profit sectors.
Competing interests None declared.
Provenance and peer review Not commissioned; externally peer reviewed.
Data availability statement Data are available upon request
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