Remote Camera Technology and its Role in Grey Seal Haul-out Assessment

Abstract

Remote cameras can permit non-invasive monitoring of marine species and habitats. Using automated time-lapse cameras in combination with human observations and an infrared visitor counter, this project collected data on the daily maximum number of grey seals (Halichoerus grypus) hauled-out and daily numbers of visitors at a major grey seal haul-out location in Cornwall, south west England between August 2013 and December 2017. This project assesses the uses of data captured by time-lapse cameras to quantify seasonal patterns of grey seal haul-out abundance and how haul-out patterns might be influenced by environmental conditions, as well as quantifying counts of pups (as pup positive days) during the grey seal pupping season (Chapter 1). Using this knowledge, the project combines data from human-led surveys with time-lapse cameras to quantify the effects of human disturbance at a grey seal haul-out (Chapter 2). The peak in grey seal haul-out abundance occurred in March and April with median daily maximum grey seal haul-out counts of 103 seals (± 52.00 IQR, range 52 to 188) and 83 seals (± 46.00 IQR, range 25 to 239) respectively. The largest range in daily visitor numbers occurred in April (range 23 to 743) coinciding within the peak period in grey seal abundance but the peak period for visitor numbers at the site occurred in August in 2014 and 2015 with median daily visitor counts of 381 (± 102.00 IQR, range 77-471). Grey seal white-coated pups were observed on a total of 99 days during three seasons of monitoring (2013, 2014, 2017) with the highest number of pup positive days occurring in September (median 15 ± pup positive days 4.00 IQR) and October (median 13 pup positive days ± 2.50 IQR) each year. ‘People on cliff’ disturbances were more likely to disturb grey seals into the sea than other stimuli and as such, reduced the number of grey seals hauled-out on the beach during a disturbance event. This project concludes with a discussion of the potential impacts of disturbance at the haul-out site, with the findings highlighting the value of using time-lapse camera technology in effectively monitoring a pinniped population for a prolonged period and the implications of disturbance and the need for management action.