Our Porpoise Photo ID project, funded by the Postcode Local Trust and the WCVA, takes advantage of Sea Trust’s photographic expertise provided by our volunteer photographer Ken Barnett, the high proportion of ‘marked’ porpoise seen locally and the concentration of porpoise around Strumble Head to carry out a study into the population dynamics, site fidelity and behaviour of porpoise in this area. Our porpoise photo ID volunteers who carry out these surveys 6 days a week, building up a large catalogue of images which have already produced individual porpoise matches with previous seasons. This project also aims to equip these volunteers with practical skills such as photographic techniques, as well as soft-skills, such as team-work and public speaking, which are highly desirable in the workplace.
What are we doing right now?
This field season, our primary aim is to develop our method for establishing this as an on-going research project. We also aim to collect data on individual porpoise that use Strumble Head and Fishguard Bay, mother and calf pair numbers, site fidelity and behaviours. By documenting individual animals that visit the Fishguard Bay and Strumble Head area, we aim to acquire a greater understanding of the harbour porpoise population residing in and around these areas. The data collected as part of this project will contribute towards answering questions regarding harbour porpoise site usage, behaviours, provide additional information of the range of the local population as well as the potential effects of human activities on their behaviour.
Photo-ID of dolphins has been widely used as a way of identifying individuals and monitoring population dynamics (i.e. size, social structure, population composition) since the late 1970s. This method involves photographing specific body parts that have particular physical characteristics unique to the individual. Individuals are often identified by permanent and semi-permanent marks on their dorsal fins – nicks, notches, scarring from teeth rakes and pigmentation patterns. Images collected over time can then be matched using these identifiable marks. There is some debate around the permanency of marks, however, nicks/ notches are considered to be permanent (Urian et al., 2016), and that is predominantly what we see around Strumble Head.
Photo-ID is one of the least invasive methods of monitoring individuals, as you never have to physically come in contact with the animals. Photo-ID methods have become more sophisticated, methodical and standardised. As the methods develop, they are increasingly being used for population abundance estimates, and monitoring of population composition and social structure.
Photo-identification (Photo-ID) of the local harbour porpoise population has never been done before, partly due to the restrictions of observing porpoise in this area, which are boat shy, meaning land-based surveys are the better option. Land-based surveys remove any bias from porpoise behaviour due to a boat’s varying presence/ absence, but it does bring increased photographic challenges. Camera technology has improved to the point where it is now possible to get usable images from Strumble Head, a known harbour porpoise and general cetacean hotspot.
We believe that North West Pembrokeshire is an important area for harbour porpoise, and particularly the Strumble Head area. This study will help us to explain the ways that porpoise use this and surrounding areas, and what environmental or other factors may make the area attractive to porpoise.
This project initially will monitor and collect data on
- Individuals that use Strumble Head and Fishguard Bay
- How often we see these individuals (site fidelity)
- Group size estimates
- Mother and calf pairs
Later stages of the project
Phase 2 of the project will look at the population structure (open/ closed…) and the home range of the marked individuals by expanding the project out to other groups surveying porpoise around the coast.
Phase 3 of the project will look at the environmental drivers (influencing factors) that can help to explain the importance of the areas, e.g. a factor influencing prey density, which in turn can help to predict what environmental features need most protection to maintain these populations.
For more information on the project, get in touch using the contact info on our Contact page.
Urian, K., Gorgone, A., Read, A., Balmer, B., Wells, R. S., Berggren, P., Durban, J., Eguchi, T., Rayment, W. and Hammond, P. S. (2015), Recommendations for photo-identification methods used in capture-recapture models with cetaceans. Marine Mammal Science, 31: 298–321. doi: 10.1111/mms.12141