[MARMAM] New Publication: Reproductive biology of male common dolphins (Delphinus delphis) in New Zealand waters

Emily Palmer emilyisobelpalmer at gmail.com
Sun Oct 8 13:35:03 PDT 2023

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 male common
dolphins in New Zealand waters.

Palmer EI, Betty EL, Murphy S, Perrott MR, Smith ANH, and Stockin KA
(2023). Reproductive biology of male common dolphins (*Delphinus delphis*)
in New Zealand waters. Marine Biology 170, 153.

Reproductive parameters were assessed in 64 male common dolphins (*Delphinus
delphis*) examined post-mortem from strandings and bycatch in New Zealand
between 1999 and 2020. The stages of male sexual maturation were assessed
using morphological measurements and histological examination of testicular
tissue. Age was determined via growth layer groups (GLGs) in teeth. The
average age (ASM) and length (LSM) at attainment of sexual maturity were
estimated to be 8.8 years and 198.3 cm, respectively. Individual variation
in ASM (7.5–10 years) and LSM (190–220 cm) was observed in New Zealand
common dolphins. However, on average, sexual maturity was attained at a
similar length but at a marginally younger age (< 1 year) in New Zealand
compared to populations in the Northern Hemisphere. All testicular
variables proved better predictors of sexual maturity compared to
demographic variables (age and total body length), with combined testes
weight the best outright predictor of sexual maturity. Reproductive
seasonality was observed in male common dolphins, with a significant
increase in combined testes weight in austral summer. This aligns with most
other studied populations, where seasonality in reproduction is typically
observed. Given the known anthropogenic impacts on New Zealand common
dolphins, we recommend that these findings be used as a baseline from which
to monitor population-level changes as part of conservation management

Open Access the full research from here:

Thank you very much and ngā mihi nui,

Emily Palmer

PhD Candidate | Cetacean Ecology Research Group | School of Natural
Sciences | Massey University

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