Google Haul Out: Earth Observation Imagery and Digital Aerial Surveys in Coastal Wildlife Management and Abundance Estimation

Abstract

As the sampling frequency and resolution of Earth observation imagery increase, there are growing opportunities for novel applications in population monitoring. New methods are required to apply established analytical approaches to data collected from new observation platforms (e.g., satellites and unmanned aerial vehicles). Here, we present a method that estimates regional seasonal abundances for an understudied and growing population of gray seals (Halichoerus grypus) in southeastern Massachusetts, using opportunistic observations in Google Earth imagery. Abundance estimates are derived from digital aerial survey counts by adapting established correction-based analyses with telemetry behavioral observation to quantify survey biases. The result is a first regional understanding of gray seal abundance in the northeast US through opportunistic Earth observation imagery and repurposed animal telemetry data. As species observation data from Earth observation imagery become more ubiquitous, such methods provide a robust, adaptable, and cost-effective solution to monitoring animal colonies and understanding species abundances.

Marine top predators as climate and ecosystem sentinels

“…For instance, satellite imagery has been used to document both the recovery of gray seal ( Halichoerus grypus ) populations in New England (Moxley et al . ) and an 88% decline in the world's largest king penguin ( Aptenodytes patagonicus ) colony (Weimerskirch et al . ).…”

“…Increases in remote-sensing capacity also have major implications for sentinel science. For instance, satellite imagery has been used to document both the recovery of gray seal (Halichoerus grypus) populations in New England (Moxley et al 2017) and an 88% decline in the world's largest king penguin (Aptenodytes patagonicus) colony (Weimerskirch et al 2018). Consequently, population estimates of animals in remote locales can be obtained more frequently and more broadly than is possible through traditional survey methods.…”

Genomic signatures of population bottleneck and recovery in Northwest Atlantic pinnipeds

“…States, estimates of harbor seal population size have grown from 5,000 in the early 1970s (Richardson, 1976) to over 75,000 today (Waring et al, 2016), and gray seals have returned from essentially absent until the early 1990s (Gilbert et al, 2005) to 30,000-50,000 today (Moxley et al, 2017).…”

“…Following the cessation of bounties, enactment of local protection (Lelli & Harris, 2006), and passing of the US Marine Mammal Protection Act of 1972, population surveys have documented the rapid return of these seals over the past several decades (Bowen, den Heyer, McMillan, & Hammill, 2011; Gilbert, Waring, Wynne, & Guldager, 2005; Waring, Josephson, Maze‐Foley, & Rosel, 2016). In the Northeast United States, estimates of harbor seal population size have grown from 5,000 in the early 1970s (Richardson, 1976) to over 75,000 today (Waring et al., 2016), and gray seals have returned from essentially absent until the early 1990s (Gilbert et al., 2005) to 30,000–50,000 today (Moxley et al., 2017). …”

Will Culling the Northwest Atlantic Gray Seal Population, Halichoerus grypus (Fabricius, 1791) (Carnivora: Phocidae) on Cape Cod, Massachusetts, USA Reduce the Risk of Human-White Shark Encounters?

“…A tagging and tracking study of the white shark has been undertaken by the Massachusetts Marine Fisheries Service and the University of Massachusetts (Skomal et al 2017). Gray seals are being studied and tracked to learn more about their migratory behavior and role in local ecosystems (Moxley et al 2017). Towns on the Outer Cape along with the Atlantic White Shark Conservancy and the Cape Cod National Seashore have recently commissioned a study on options for mitigating the risk of human-shark encounter in local waters 20 .…”