Short-beaked common dolphin (Delphinus delphis) total length estimation using laser photogrammetry off the southwest coast of Ireland
Main Article Content
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.
Article Details
This work is licensed under a Creative Commons Attribution-NonCommercial 4.0 International License.
You are free to:
- Share copy and redistribute the material in any medium or format
- Adapt remix, transform, and build upon the material
- The licensor cannot revoke these freedoms as long as you follow the license terms.
Under the following terms:
- Attribution You must give appropriate credit, provide a link to the license, and indicate if changes were made. You may do so in any reasonable manner, but not in any way that suggests the licensor endorses you or your use.
- NonCommercial You may not use the material for commercial purposes.
- No additional restrictions You may not apply legal terms or technological measures that legally restrict others from doing anything the license permits.