Southern right whale Eubalaena australis in Golfo San Matías (Patagonia, Argentina): Evidence of recolonisation

Abstract

Since the 1980s, the distribution range of the southern right whale (Eubalaena australis) in Argentina was mostly located in the winter calving grounds around Península Valdés. After the international moratorium that forbade the commercial hunting, southern right whales have shown signs of recovery during the last few decades. Nowadays, it is thought that the species is experiencing a density-dependent process while expanding its distribution range in Patagonia. From 2007 to 2016, data on right whale distribution, group composition and relative abundance were collected in Golfo San Matías, Patagonia through aerial surveys. Generalized linear models with a negative binomial error distribution were used to determine the population trend of right whales in this area. In addition, the group composition and the relative abundance of right whales among the northern Patagonian gulfs were compared. Finally, a literature review was conducted to assess the historical presence of right whales in Golfo San Matías, revealing the presence of right whales in Golfo San Matías during and after the commercial exploitation. During aerial surveys (2007–2016), right whales were observed from August to October in the area, with a peak in late August-early September. Our results suggested a geographic distribution change with a regular use of the northwest coast of the gulf in recent years and a positive trend in the population growth rate inside Golfo San Matías. This area was dominated by unaccompanied whales (solitary individuals and breeding groups) as opposed to Península Valdés where the dominant group type was the mother calf pairs. Therefore, Golfo San Matías appears to be important for socializing and mating but not as a nursery ground. In addition, the density of whales was four times greater in the gulfs of Península Valdés. Our findings contribute to a better understanding of the recovery of this species in Patagonia, Argentina and should be considered for the management measures for right whales in this region.

The Falkland Islands (Malvinas) as sub-Antarctic foraging, migratory and wintering habitat for southern right whales

“…The steady increase in SRW populations following the cessation of whaling, may lead to both recolonization of former grounds and expansion of range into previously less favoured areas adjacent to existing wintering grounds, potentially including the Falklands. For example, the high growth rates recently observed at Golfo San Matías (10% per year; Arias et al ., 2018) north of PV, are consistent with a redistribution of whales and may be linked to PV approaching its carrying capacity as an optimal habitat (Crespo et al ., 2019). Ongoing distribution and abundance monitoring is required to clarify the status of SRWs in the Falklands, in both the offshore summer feeding areas and in nearshore waters during the late autumn and winter.…”

“…Therefore it is unlikely that SRWs were giving birth or nursing in nearshore Falkland waters during 2017 or 2018. However, recolonizations of former grounds (or discovery of new ones) may begin with a predominance of solitary animals or mating groups (Carroll et al ., 2014; Arias et al ., 2018). Although most SRW calving areas are located north of 45°S, some do occur at higher latitudes.…”

Antofagasta Region in northern Chile, a potential nursing ground for the Southern right whale Eubalaena australis

“…Either some CPe SRW also have white blazes or, alternatively, the whale in Bahía Moreno may be of SW Atlantic origin and if so, may be 'recolonizing' the SE Pacific coastal habitat. Recolonization of pre-whaling historic habitats of SRW has been observed in the SW Atlantic population, thus we could expect this from the CPe subpopulation 4 (Arias et al, 2018). More comparative research (e.g.…”

A Potential Nursing Ground for the Southern Right Whale <i>Eubalaena australis </i>in Northern Chile

“…Either some CPe SRW also have white blazes or, alternatively, the whale in Bahía Moreno may be of SW Atlantic origin and if so, may be 'recolonizing' the SE Pacific coastal habitat. Recolonization of pre-whaling historic habitats of SRW has been observed in the SW Atlantic population, thus we could expect this from the CPe subpopulation (Arias et al, 2018;Crespo and Coscarella, 2020).…”