The Project

AIMS

Identify scientifically robust and potentially effective Management Units for harbour and grey seals in western European waters using genetic tools.
Assess trends in genetic diversity in harbour seals following large-scale epizootics in Europe.
Investigate harbour seal habitat use in chosen Irish protected areas (SACs) using genetic and photo-ID tracking techniques.

Grey seals hauled out at the Great Blasket Island, Ireland.

BACKGROUND

Grey seals and harbour seals are protected in Ireland under national and European legislation, including through the designation of Special Areas of Conservation (SACs) under the EU Habitats Directive, and via the Marine Strategy Framework Directive (MSFD) which proposes the identification of Management Units (MUs) for each species. Little is known about the genetic make-up of Irish seals and their vulnerability to environmental problems or human impacts. Due to large-scale mortality during past demographic events – such as PDV (Phocine Distemper Virus) outbreaks, levels of genetic diversity may have substantially been lowered in harbour seals as a result of population bottlenecks. A loss of genetic diversity could influence individual fitness, cause inbreeding depression and reduce the seal’s ability to adapt to changes in the environment. Furthermore, both seal species are at the outer limits of their ranges, which makes it important to understand if their marginal positions in the main distributional ranges of the populations have an effect on exchange rates of migrants to neighbouring aggregations. Effective management and conservation of protected species does not only require an understanding of distribution and population size at a specific point in time. It is rather crucial to understand how this changes with time as it might be impacted by both natural and human influences. It is therefore important to identify current as well as past demographic trends in data deficient marine populations which includes Irish seals.

DATA COLLECTION

Sample collection focuses on the main representative haul-outs for both species. Grey seals are sampled during the moult (February to April) and the breeding season (October to November) where sites include the Inishkea island group, Inishark, the Great Blasket, the Great Saltee, and Lambay Island. Harbour seals are sampled during the moult (August to September) where sites include Killala Bay, Galway Bay, Glengarriff, and Tern Island (Wexford). The Killala Bay and Galway Bay sites are surveyed for habitat use once a month.

The following data are collected at each of those sites:

Seal scat samples – We collect seal scat for both grey and harbour seals which is used to extract DNA and analyse population structure.
Seal hair samples – For grey seal pups (target are whitecoats, S3) during the breeding season, we collect hair as scat is mostly not available and would be fairly liquid. We also collect moulted hair of harbour seals as an additional and easily collectable source of DNA.
Seal carcasses – If carcasses are present at the site, we do collect further samples for genetic analysis, e.g. skin or bone.
Harbour seal DNA – All above mentioned sources of DNA are also used for habitat use of harbour seals. Using a number of nuclear markers, called microsatellites, it is possible to identify individuals and include the data in mark-recapture analyses.
Photographs – For habitat use of harbour seals we collect photographs. Harbour seals display a unique pelage pattern that can be used to identify individuals (see picture). Using these photographs, we can create sightings histories for each individual and investigate habitat use via mark-recapture techniques.

Additional samples/data are available from a number of Irish and European collaborators.