Population trends of harbour and grey seals in the Greater Thames Estuary

Abstract

In this paper, results from two decades of seal population data for the Greater Thames Estuary between 2003 to 2019 are presented, together with the results of two harbour seal pup surveys conducted in 2011 and 2018. Counts of hauled out harbour and grey seals were conducted during aerial surveys and these have been scaled up to estimate population sizes. Most recent population estimates suggest ~900 harbour and ~3,200 grey seals reside in the Greater Thames Estuary. Both species have shown an upward population trend since surveys began in 2003. The wide distribution and growing number of seals across the Greater Thames Estuary over the last two decades shows the importance of this region for both species. It also highlights the value of long-term monitoring data to compliment seal surveys taking place elsewhere in the UK.