Long‐term patterns in harbour seal site‐use and the consequences for managing protected areas

Abstract

There have been marked declines of UK harbour seal populations over at least the last decade. Protected areas, such as Special Areas of Conservation (SACs), provide one tool to improve the conservation status of these populations. However, the design and management of SACs is often limited by a lack of information on long-term patterns in the use of seal haul-out sites and foraging areas. The Moray Firth is the only UK region where long-term harbour seal population studies have been conducted in parallel with detailed studies of foraging ecology. We used this opportunity to investigate changes in the use of haul-out sites and foraging areas within two adjacent estuaries, where annual haulout counts were made over a 20-year period. In 1988, 499% of seals and all mother-pup pairs were located at haul-out sites within an area that was subsequently designated as a SAC to protect harbour seals. In addition to previously reported declines in this area, we detected a shift in haul-out distribution resulting from the development of a new pupping site that, by 2008, held 37% of mother pup pairs in the area. Foraging areas of breeding females were compared in 1989 and 2009 using a combination of VHF and GPS-GSM telemetry, confirming that females foraged in broadly similar areas in both periods. This suggests that the development of this new pupping site was not driven by the need to forage further offshore, but instead was more likely due to local variation in haul-out site characteristics. These results are discussed in relation to potential drivers of haulout site choice and the need to develop a broader suite of measures for managing habitat quality within this and other SACs for harbour seals.

Variation in breeding phenology provides insights into drivers of long-term population change in harbour seals

“…The study was carried out in the Loch Fleet National Nature Reserve in the Moray Firth, northeast Scotland [31], where individual harbour seals hauling-out onto the main sandbank in the estuary could be recognized using photo-identification techniques [27]. Data were collected daily during the pupping season (1 June to ca 22 July) from 2006 to 2011, with fewer regular surveys in late May and late July.…”

“…Prior to the development of Loch Fleet as a breeding site in the late 1990s [31], the Cromarty Firth had been the most accessible regional breeding site for behavioural observations and counts of mothers and pups [36,37], therefore providing the best time series of counts to investigate longterm variation in the timing of pupping. Regular counts of adults and pups were made using a telescope from shorebased vantage points during the breeding season (1 June -31 July) as described in Thompson et al [35].…”

“…Variations in the timing of pupping were related to local population size by using the annual mean count of adults at all sites within the inner Moray Firth [35,38]. Estimates of local population size since 2006 have been collected using aerial surveys by the Natural Environment Research Council Sea Mammal Research Unit and are taken from Cordes et al [31] and the 2011 Special Committee on Seals report [39].…”

Ontogeny in marine tagging and tracking science: technologies and data gaps

“…As the Global Positioning System (GPS) has a higher accuracy than ARGOS (km for ARGOS, m for GPS; Hazel 2009, Costa et al 2010a) GPS receivers are often inserted in ARGOS tags. Alternatively, GPS data can be stored on-board for retrieval upon tag recovery for animals with regular surfacing bouts (Phalan et al 2007, Cordes et al 2011. Fastloc GPS receivers have revolutionized the potential for GPS technology use in marine animals, as they gather positioning data in less than a second and therefore allow positioning even during short surfacing events (Sims et al 2009, Costa et al 2010a, Witt et al 2010a.…”

Seals, salmon and stakeholders: integrating knowledge to reduce biodiversity conflict

“…1a). In marked contrast, no other seals caught and tagged in the Moray Firth have been detected in rivers (Thompson et al, 1996;Sharples et al, 2008;Cordes et al, 2011). These data are extremely limited and inconclusive; nevertheless, they do support the case presented in Graham et al (2011).…”