Recovery of South American fur seals in the central South Atlantic Ocean

Abstract

Worldwide pinnipeds were extensively harvested for their oil and skin. This exploitation led to population declines or pushed several species to the brink of extinction (Bonner, 1982; Heckel & Schramm, 2021; Kovacs et al., 2012). Due to their intrinsic characteristics, such as large-bodied, low reproductive rates and long generation times, these species exhibit low resilience to exogenous perturbations and slow postharvesting recoveries (Gerber & Hilborn, 2001; McLaren & Smith, 1985). The South American fur seal (SAFS, Arctocephalus australis) is distributed along the southwestern Atlantic and the southeastern Pacific coasts of South America (Cárcamo et al., 2019; Cárdenas-Alayza et al., 2016). A recent estimated global population is 393,500 individuals (Crespo & Oliveira, 2021). This species was intensively exploited from the 18th century until the end of the 20th century (Arnould, 2008; Ponce de León, 2000; Vaz-Ferreira, 1982), resulting in extirpation from most of their former range (Crespo & Oliveira, 2021; Vales et al., 2017). After the cessation of sealing, local SAFS populations across the Southern Atlantic are recovering at different rates (Crespo & Oliveira, 2021; Crespo et al., 2015; Franco-Trecu et al., 2019), and the species is classified globally and regionally as Least Concern (Cárdenas-Alayza et al., 2016; Vales et al., 2019). In the Atlantic Ocean, SAFS have been recorded in southern Brazil (Procksch et al., 2020), Uruguay (Franco Trecu et al., 2019), Argentina (Crespo et al., 2015), and the Falkland Islands (Islas Malvinas; Baylis et al., 2019), at several breeding and nonbreeding colonies (Figure 1). Genetic studies indicate reproductive isolation between Peruvian and Uruguayan populations (Oliveira et al., 2008; Túnez et al., 2007), with gene flow connectivity between southern Chile and the Atlantic (Rodrigues et al., 2018). Movements of SAFS from Uruguay and the Falkland Islands to Patagonia have been demonstrated (Baylis et al., 2018; Crespo et al., 2015; Riaz et al., 2023). Onthe Atlantic coast, breeding colonies show a discontinuous distribution, with the greatest breeding activity in the northern and southern extremes of the region (Figure 1; Crespo & Oliveira, 2021; Túnez et al., 2008). For several years, Isla de Lobos, off the Uruguayan coast, was considered the world´s largest breeding colony (Crespo et al., 2015), with an estimated pup abundance of 31,160 pups in 2013 (Franco-Trecu et al., 2019). However, in recent years, the Falkland Islands reported a production of more than 36,000 pups, redefining SAFS abundance and the contribution of breeding locations in the Atlantic (Baylis et al., 2019).