[MARMAM] New publication - Short-beaked common dolphin (Delphinus delphis) total length estimation using laser photogrammetry off the southwest coast of Ireland

[Sean O'Callaghan]

Dear MARMAM community,

We are pleased to announce our recent publication on common dolphin laser
photogrammetry detailed below.

O'Callaghan, S.A., Daly, M. and Berrow, S. (2023). Short-beaked common
dolphin (Delphinus delphis) total length estimation using laser
photogrammetry off the southwest coast of Ireland. Journal of Cetacean
Research and Management 24(1):189-204.
https://doi.org/10.47536/jcrm.v24i1.395

Abstract
Measurements from 106 stranded short‐beaked common dolphins along the Irish
coast were taken between March 2017 and March 2023. Data were collected
from the Irish Necropsy Project and Irish Cetacean Stranding Scheme. Total
length measurements were gathered from 103 individuals where the tail
flukes were still attached. These ranged between 96–238cm, mean 185.7cm, SD
31.43cm. Males (n = 58) ranged from 96–238cm, averaging 189cm, SD 34.64cm.
Females (n = 40) measured 117.5–231cm, averaging 181cm, SD 25.80cm. Scaled
dorsal fin photos were taken from stranded dolphins to formulate an
equation to estimate the total length of live dolphins. The total lengths
of 29 live common dolphins were estimated off the southwest coast of
Ireland using laser photogrammetry and dorsal fin dimensions between March
2018–April 2019. Total lengths for three stranded dolphins with amputated
tail flukes were also estimated. Dorsal fin base lengths were the most
accurate predictor of total length R2 = 0.78. Total length estimates ranged
between 143.77–242.25cm, averaging 194.78cm, SD 20.05cm. The adoption of
laser photogrammetry as a measurement tool warrants further exploration as
a means to reduce potential disruption from aerial systems and enhance the
utility of behavioural and photo‐ID images. This study describes a
non‐invasive technique with a range of possible applications for
understanding pod size structure and seasonality due to this species’
approachable behaviour and inquisitive nature.

The study is freely available to download  in the below link but if you you
have any questions regarding this work feel free to get in touch with me on
seanocallaghan...@gmail.com

https://journal.iwc.int/index.php/jcrm/article/view/395?fbclid=IwAR3onplj0UeWtH725ZWdOhrBdzmJytHBnBVSzsKqx1ouQCmZ4cYMNVLxDgU

Kind regards and happy holidays,

Seán
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[MARMAM] New publication: Sowerby's beaked whale neonate and pregnant female strandings in Ireland

[Sean O'Callaghan]

Dear colleagues,



Our study documenting a live stranding of a neonate Sowerby’s beaked whale
in 2017 and a pregnant female in 2020 in the southwest of Ireland was
recently published.



O’Callaghan SA, Overy L, Hunt L, Foxall D, Collins M, O’Connell M (2022).
Strandings of a neonate and a pregnant Sowerby’s beaked whale (*Mesoplodon
bidens* (Sowerby, 1804)) in Ireland. *Journal of the Marine Biological
Association of the United Kingdom* 1–6.
https://doi.org/10.1017/S0025315422000492



Abstract

Sowerby’s beaked whale is a deep-diving cetacean species specialized to
live in the deep waters of the North Atlantic, including offshore Irish
waters. Sightings of Sowerby’s beaked whales in this area are infrequent
and a substantial increase in our knowledge of their presence comes from
recent static acoustic monitoring (SAM) and passive acoustic monitoring
(PAM). However, most information on this species has been derived from
stranding records, which provide opportunistic insights into this elusive
species’ cryptic life history. Here we report on the live stranding of a
1200mm long neonate and an adult 5m female Sowerby’s beaked whale in July
2015 and on the stranding of a 4.9m pregnant female in September 2020 with
a 495mm long male foetus in the south-west of Ireland. These stranding
events provide an important insight into the reproductive life history of
this species and provide further evidence that Sowerby’s beaked whales
calve in offshore Irish waters.



The article is available in the below link but feel free to contact me for
a copy if you are interested on seanocallaghan...@gmail.com



https://www.cambridge.org/core/journals/journal-of-the-marine-biological-association-of-the-united-kingdom/article/strandings-of-a-neonate-and-a-pregnant-sowerbys-beaked-whale-mesoplodon-bidens-sowerby-1804-in-ireland/6411828BAFA427F8E7C663DA017F9AEB



Regards,



Seán

PhD candidate, Atlantic Technological University


Twitter: @KerrysWildside
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