Kia Ora MARMAMers, My co-authors and I are pleased to announce our recent publication of an international collaboration involving Massey University, Atlantic Technological University, Department of Conservation (DOC) and our iwi partners to offer first insights to the reproduction of female common dolphins in New Zealand waters. Palmer EI, Betty EL, Murphy S, Perrott MR, Smith ANH, and Stockin KA (2022). Reproductive biology of female common dolphins (Delphinus delphis) in New Zealand waters. Marine Biology 169, 158. https://doi.org/10.1007/s00227-022-04139-3 Abstract: Reproductive biology was assessed in 106 female common dolphins (Delphinus delphis) examined post-mortem from stranding and bycatch events along the New Zealand coastline between 1997 and 2019. The average age (ASM) and length (LSM) at sexual maturity was estimated at 7.5 years and 183.5 cm, respectively. The total number of corpora in mature individuals increased with age and appeared to persist throughout life. Ovarian asymmetry was apparent, with the left ovary displaying higher rates of ovulation, and a maximum of 19 corpora recorded for a 24-year-old female. The estimated ovulation and annual pregnancy rates for mature females were 0.39 year−1 and 30%, respectively. Conception and calving occurred year-round, with a weak seasonal increase observed in late austral spring and early austral summer. As these data did not clearly show whether seasonality was present, the gestation, lactation, and resting periods were calculated as either 12.6 or 12.8 months based on the presence/absence of seasonality, respectively. Similarly, calving interval ranged from 3.15 to 3.2 years, depending upon whether seasonality was considered. The estimated LSM of the New Zealand population aligns with other populations globally, although the estimated ASM is younger by approximately 6 months. Other reproductive parameters align with Northern Hemisphere populations, although demonstrate variation, which may reflect adaptations to local conditions such as water temperature and prey availability. As the species is subject to anthropogenic impacts including pollution and bycatch, we suggest our findings be used as a baseline with which to monitor trends in population parameters. Open Access the full research from here: https://doi.org/10.1007/s00227-022-04139-3 Thank you very much and ngā mihi nui, Emily
Emily Palmer PhD Candidate | Cetacean Ecology Research Group | School of Natural Sciences | Massey University https://www.cetaceanecology.org/
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