A comparison of the number of grey seals (Halichoerus grypus) using two tidal haul-outs in Cornwall, UK. Luke F. Blakemore University of Plymouth, Cornwall College Campus, Falmouth, Cornwall, TR11 3QS This study investigated the abundance of grey seals at two tidal haul-outs in Cornwall. Land based surveys were carried out on twelve days at Gwennap Head and nine days at Pendennis Point within a six week period. A boat based survey took place on three separate days observing Black Rock, Falmouth. Observations took place one hour before, half an hour before, half an hour after, one hour after low tide and at low tide. At each period the number of seals, and whether they were hauled-out or no, were recorded. Where possible the age and sex of each seal were also recorded. Photographs were taken whenever possible and where used to create a photo identification database for grey seals within the Fal. Results showed that there was no significant difference in the number of seals sighted at Black Rock and Gwennap Head but they did indicate that sea state may affect grey seals hauling-out. The data collected may help future projects within this field. The photo identification database will help with future work and can be linked into and used by local and regional organisations and businesses to identify ‘local’ seals within Falmouth and to help track travelling patterns by individuals.
Keywords: numbers, grey seals, Cornwall, Falmouth, Porth Gwarra, Black Rock, Hella Point
INTRODUCTION The worlds grey seal populations can be split into three isolated populations – the East Atlantic, West Atlantic and the Baltic (Boskovic et al. 1996). Around 45% of the world’s population can be found around the British coast (SCOS, 2008), with 0.5% of this found around Cornwall and the Isles of Scilly (ibid). In 2007 it SCOS stated that the total UK population was increasing at around 2.5% per year. With almost half the world’s population of grey seals found around the UK, it is important to monitor numbers and distribution. Whilst spending most of their lives at sea, grey seals regularly ‘haul-out’ on beaches and rocky outcrops. Seals haul-out for a number of reasons including courting, breeding, bathing in sun to warm themselves, to rest and to allow food to digest. Haul-outs are therefore important for the survival of grey seals. Although an important aspect of seal
ecology, there is no true definition as to what classifies a seal haul-out (Sayer, 2010) Although there is no true definition of a haul-out, there are areas that can be identified in which seals often haul out, these are usually deemed to be seal ‘haul-outs’. These are usually areas that are inaccessible by land, such as coves, caves, rocky out-crops and small islands. Due to the need for seals to haul-out, it is therefore important to monitor the usage of haulouts to help indicate if there is a decline or increase in seal numbers. There has been a significant growth to marine mammal tourism worldwide due to their appeal and ease of access from coastal areas (Constantine, 1999) and within Cornish waters the grey seal is the most commonly seen marine mammal (Barnett & Wescott 1999). As such it becomes more important to monitor seal populations and the numerous threats to their well being, such as boating activities, habitat loss (Harwood, 2001), pollution (Wolkers et al, 2004) and fisheries (through by-catch, overfishing or culling).