Grey and Harbour Seals Along the West Coast of Ireland: Implications for Management & Conservation

Student Spotlight - María Pérez Tadeo

PhD Research at the Marine & Freshwater Research Centre (Galway-Mayo Institute of Technology) 

Email: maria.pereztadeo@research.gmit.ie   Twitter: @mariaptadeo   Website: https://mfrc-gmit.ie/meet-the-team/maria-perez-tadeo/

Background

Grey seals (Halichoerus grypus) and harbour seals (Phoca vitulina) are protected species in Ireland, listed under Annex II of the EU Habitats Directive (92/43/EEC). This means that their populations are subject to monitoring programs and their important habitats must be considered as Special Areas of Conservation (SACs).

However, still today, pinnipeds face a range of threats. Anthropogenic activities such as tourism lead to an increase in human-wildlife interactions and consequently, to disturbances. Disturbances have shown to trigger changes in the behaviour of pinnipeds, increasing the display of vigilance and flushing behaviours and hence reducing resting and nursing times. This might lead to increased stress levels, heart rates, and energetic expenditure which can affect the animal's fitness. In some cases, disturbances could also lead to habitat displacement, forcing individuals to search for areas that might present a lower productivity or be less suitable for resting and breeding.

Inhabiting both terrestrial and marine environments, and due to their colonial terrestrial breeding, pinnipeds are highly vulnerable to habitat degradation due to industrial coastal development and pollution.

Another significant threat to pinnipeds is the interaction with commercial fishing, leading to bycatch and entanglements in fishing gear. Furthermore, as seals might compete for the same resources, this leads to a reduction in prey availability.

Fieldwork

Fieldwork was the most challenging and rewarding part of my PhD project. During a two-year period, I spent several months collecting grey and harbour seals’ behavioural and acoustic data in the Blasket Islands SAC and at different locations around Galway Bay.

Assessment of anthropogenic disturbances

Ecotourism

One of the chapters of the project focused on the assessment of anthropogenic disturbances due to ecotourism on a grey seal colony in the Blasket Islands Special Area of Conservation (SAC), in the southwest of Ireland (Pérez Tadeo et al., 2021).

The Blaskets Islands (Co. Kerry) host one of the most important grey seal colonies in Ireland, where the breeding season partially overlaps with the tourist season. Disturbances caused by ecotourism activities were evaluated. An increase of vigilance behaviour and seals entering the water were observed in the presence of ferries within a distance of 500 m from the colony and tourists on the beach where seals were hauled-out also had a very significant effect. Based on our results, which show that a strict code of conduct for tourists and vessels is needed, we devised recommendations on best practices for ecotourism with the aim of reducing disturbances of grey seals in the Blasket Islands.

Drones

The effect of disturbances due to the use of drones on the haul-out behaviour of harbour seals was assessed at two different colonies in Galway Bay, west coast of Ireland.

After disturbance thresholds were identified we provided recommendations on best practices for the use of drones with the aim of reducing disturbances of harbour seals in future research studies.

Baseline Behaviours

The abundance and haul-out behaviour of harbour seals were studied at two colonies located in Galway Bay. This study will shed light on the baseline behaviour and the potential movements of harbour seals within the bay, providing monitoring information that could be used in the design of conservation and habitat management plans for this species at a local scale.

Underwater Vocalisations

A recording device was deployed to record grey seal underwater acoustic vocalisations from a colony located in the Blasket Islands SAC. We will try to identify some characteristics, assess differences in parameters between day and night as well as between times when anthropogenic disturbances were present.

Final Messages

The increase in anthropogenic activities in coastal areas such as aquaculture, construction, renewable energy, tourism, and pollution should take into account the presence of pinnipeds, to avoid adverse effects on these protected species.

More site-specific research and monitoring programs are needed to assess human disturbances to wildlife in general and to these species in particular, as well as the implementation of regulations, guidelines, codes of conduct, etc.

It is hoped these results will help inform policy regarding the conservation and management of these protected species, therefore helping Ireland to fulfil its responsibilities, as required under the Habitats Directive and the Marine Strategy Framework Directive.

References

Anderwald, P., Brandecker, A., Coleman, M., Collins, C., Denniston, H., Haberlin, M. D., O’Donovan, M., Pinfield, R., Visser, F., & Walshe, L. (2013). Displacement responses of a mysticete, an odontocete, and a phocid seal to construction-related vessel traffic. Endangered Species Research, 21(3), 231-240.

Back, J. J., Hoskins, A. J., Kirkwood, R., & Arnould, J. P. (2018). Behavioral responses of Australian fur seals to boat approaches at a breeding colony. Nature Conservation, 31, 35-52.

Blundell, G. M., & Pendleton, G. W. (2015). Factors Affecting Haul-Out Behavior of Harbor Seals (Phoca vitulina) in Tidewater Glacier Inlets in Alaska: Can Tourism Vessels and Seals Coexist? PLoS ONE, 10(5), e0125486. https://doi.org/10.1371/journal.pone.0125486

Blundell, G. M., Womble, J. N., Pendleton, G. W., Karpovich, S. A., Gende, S. M., & Herreman, J. K. (2011). Use of glacial and terrestrial habitats by harbor seals in Glacier Bay, Alaska: costs and benefits. Marine Ecology Progress Series, 429, 277–290. https://doi.org/10.3354/meps09073

Cosgrove, R., Gosch, M., Reid, D., Sheridan, M., Chopin, N., Jessopp, M., & Cronin, M. (2016). Seal bycatch in gillnet and entangling net fisheries in Irish waters. Fisheries Research, 183, 192-199.

Cowling, M., Kirkwood, R., Boren, L., Sutherland, D., & Scarpaci, C. (2015). The effects of vessel approaches on the New Zealand fur seal (Arctocephalus forsteri) in the Bay of Plenty, New Zealand. Marine Mammal Science, 31(2), 501-519. https://doi.org/10.1111/mms.12171

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Pérez Tadeo, M., Gammell, M., & O’Brien, J. (2021). Assessment of anthropogenic disturbances due to ecotourism on a Grey Seal (Halichoerus grypus) colony in the Blasket Islands SAC, SW Ireland and recommendations on best practices. Aquatic Mammals, 47(3). https://doi.org/10.1578/AM.47.3.2021.268

Pomeroy, P. P., Fedak, M. A., Rothery, P., & Anderson, S. (1999). Consequences of maternal size for reproductive expenditure and pupping success of grey seals at North Rona, Scotland. Journal of Animal Ecology, 68(2), 235- 253. https://doi.org/10.1046/j.1365-2656.1999.00281.x

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Supervisors:

Dr. Joanne O’Brien¹ and Dr. Martin Gammell¹

¹ Marine and Freshwater Research Centre, Galway-Mayo Institute of Technology, Galway