Wide dispersal of recently weaned grey seal pups in the Southern North Sea

Abstract

Grey seals have become an important part of the ecosystem in the southern North Sea over the last 50 years. However, little is known about their spatial utilization of the German North Sea, especially in relation to the dispersal and behaviour of grey seal pups after weaning. We investigated these little-known aspects by recording the movements of 11 grey seal pups born at the largest German colony for 1–9 months after leaving the colony between 2015 and 2017. The individuals moved widely throughout the southern North Sea, including some individuals that moved far along the Danish coast or to Dutch and UK waters. A point process modelling approach revealed that pups increased their distance to Helgoland during the first 70 d at sea. The frequency of inferred foraging behaviour increased until week 7 and decreased afterwards, whereas fast travelling behaviour increased throughout the whole study period. These findings reflect the transition from naive to more experienced pups, with gradual increases in foraging effort, range and efficiency to account for their increasing energy demands for survival and growth. This study provides the first characterization of the dispersal, behaviour, and spatial utilization of recently weaned grey seal pups in the southern North Sea, which profoundly extents our knowledge of an increasingly important top predator in that area.

Combining bioenergetics and movement models to improve understanding of the population consequences of disturbance

“…We assumed that GS offspring had the same probability of exposure to piling‐related noise as their mother. However, GS pups appear to disperse more widely than adults (Carter et al 2017, 2020, Peschko et al 2020). They are therefore likely to have a lower mean probability of disturbance at a particular location.…”

Post release monitoring of rehabilitated gray seal pups over large temporal and spatial scales

“…Gray seals have a predominantly solitary nature when at sea and have shown varied individualized movements (Huon et al, 2015; Matthiopoulos et al, 2004; Peschko et al, 2020; Sayer et al, 2019), indicating that each rehabilitated seal will likely differ in its range and movement patterns after release (Austin et al, 2004; Hall et al, 2001; Peschko et al, 2020). Gray seal pups are known to travel long distances during their first few weeks after weaning, exploring habitat in their search for profitable foraging areas (Peschko et al, 2020) and site fidelity is displayed in adulthood at least at some locations (Bjørge et al, 2002; Jenssen et al, 2010; Vincent et al, 2002). In this study, traced rehabbed postrelease seals moved up to 150 km from their release site.…”

“…Postrelease monitoring in pinnipeds may involve satellite telemetry, photo‐identification, and flipper tagging. Satellite telemetry provides more detailed data on movement and behavior, including when animals are not visible (Cooke, 2008; Costa et al, 2010; Gales et al, 2009; Kelly et al, 2010; Peschko et al, 2020; Vincent et al, 2016, 2017) for up to a maximum of a year's duration and limited to relatively small sample sizes (Karlsson et al, 2005). Noninvasive photo‐identification is used internationally to study the movements, behavior, and ecology of many pinnipeds and other marine species around the world (Baird et al, 2009; Constantine et al, 2012; Cordes & Thompson, 2014; Hiby et al, 2007; Langley et al, 2018; Vincent et al, 2001).…”

“…These act in addition to a range of other factors, including climate change, habitat loss, disturbance, toxic chemical pollutants, shooting, and culling (Bowen & Lidgard, 2013; Fietz et al, 2016; Nunny et al, 2018; Simmonds, 2017). While data describing the factors affecting the first‐year survival of wild gray seal pups (Hall et al, 2001; Peschko et al, 2020) and bycatch mortality of flipper‐tagged gray seals along the Norwegian coast exists, (Bjørge et al, 2002) little long‐term postrelease monitoring has been conducted on gray seals.…”

Insights obtained from a multidecadal citizen science scheme: grey seal (Halichoerus grypus) strandings in Cornwall and Isles of Scilly (2000–2020)

“…Whitecoat pups are generally born during autumn and winter with a non-waterproof, white lanugo coat, and are weaned at around 15–21 days before all maternal care ceases and they must learn to forage independently (Pomeroy et al ., 1999; Carter et al ., 2017). Following a post-weaning fast, during which they lose up to 25% of their body mass (Noren et al ., 2008), pups leave their natal site and move into an exploratory dispersal phase before settling, often a considerable distance from their place of birth (Carter et al ., 2020; Peschko et al ., 2020). Outside the breeding season, grey seals exhibit local redistributions and partial migration to foraging grounds – often several hundred kilometres offshore and are dispersed at much lower densities (Sayer et al ., 2021; Carter et al ., 2022).…”