Abstract
North Atlantic right whalesEubalaena glacialisare most commonly observed along the eastern seaboard of North America; however, their distribution and occupancy patterns have become less predictable in the last decade. This study explored the individual right whales captured photographically from both dedicated and opportunistic sources from 2015 to 2019 in the Gulf of St. Lawrence (GSL), an area previously understudied for right whale presence. A total of 187 individuals, including reproductive females, were identified from all sources over this period. In years when more substantial survey effort occurred (2017-2019), similar numbers of individuals were sighted (mean = 133, SD = 1.5), and dedicated mark-recapture aerial surveys were highly effective at capturing almost all of the whales estimated in the region (2019:N= 137, 95% CI = 135-147). A high rate of inter-annual return was observed between all 5 study years, with 95% of the animals seen in 2019 sighted previously. Capture rates indicated potential residencies as long as 5 mo, and observed behaviors included feeding and socializing. Individuals were observed in the northern and southern GSL, regions divided by a major shipping corridor. Analyses suggest that individuals mostly moved less than 9.1 km d-1, although rates of up to 79.8 km d-1were also calculated. The GSL is currently an important habitat for 40% of this Critically Endangered species, which underscores how crucial protection measures are in this area.
Highlights
While the habitat range for the Critically Endangered North Atlantic right whale Eubalaena glacialis spans across the entire North Atlantic (IUCN 2012, Cooke 2020), they are predominately sighted and studied alongPublisher: Inter-Research · www.int-res.comEndang Species Res 46: 227–251, 20212004, Silva et al 2012)
Sightings data of right whales captured in photographs or video from 2015 to 2019 in the Gulf of St. Lawrence (GSL) were used in this study
The earliest photographed sightings occurred in mid-May (2017− 2019), and the latest was in early December in 2017
Summary
While the habitat range for the Critically Endangered North Atlantic right whale Eubalaena glacialis (hereafter referred to as ‘right whale’) spans across the entire North Atlantic (IUCN 2012, Cooke 2020), they are predominately sighted and studied alongPublisher: Inter-Research · www.int-res.comEndang Species Res 46: 227–251, 20212004, Silva et al 2012). In the USA, right whale critical habitat designation under the Endangered Species Act primarily delineates areas of importance for right whales, including for feeding and calving (NMFS 2016). Designation alone does not directly provide protection from the 2 leading causes of right whale mortality in either country: entanglement in commercial fishing gear and vessel strikes (Vanderlaan & Taggart 2009, Vanderlaan et al 2011, Sharp et al 2019). These pressures have been shown to inhibit population growth of this species (Robbins et al 2015, Corkeron et al 2018), and they occur throughout their range (Sharp et al 2019)
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