Habitat and abundance of cetaceans in Atlantic Ocean continental slope waters off the eastern USA

Abstract

This study quantifies the abundance and spatial distribution of the cetacean community occupying continental shelf edge and inner continental slope waters along the US southeast Atlantic coast. A shipboard visual line-transect survey was conducted between June and August of 2004 that included effort in waters >50m deep encompassing the shelf break and inner continental slope off the US east coast between 28°N and 38°N latitude. The abundance of nine cetacean taxa was estimated using line-transect distance analysis and an independent observer approach to correct for visibility bias. Canonical correspondence analysis was used to examine the spatial distribution of the cetaceans encountered during the survey as a function of surface temperature, surface salinity, surface fluorescence, bottom depth, and bottom slope. The abundance estimates for most species were much higher than those from a study of the area conducted in 1998. This is primarily due to increased coverage of the shelf-break region and correction for visibility bias. The multivariate analysis indicated four distinct groups of cetaceans that partitioned habitat as a function of salinity, depth, and a latitudinal gradient. These groups were associated with specific water masses and hydrographic features including mid-Atlantic shelf waters (Group I), the shelf break (Group II), mid-Atlantic slope waters (Group III), and south Atlantic slope water (Group IV). Areas where water masses converge such as the continental shelf break along the mid-Atlantic and near Cape Hatteras, North Carolina are therefore areas of both high diversity and density of cetaceans.

Occurrence, distribution and abundance of cetaceans in Onslow Bay, North Carolina, USA

“…The species composition and distribution patterns observed were similar to those recorded during previous broad-scale surveys of the South Atlantic Bight and Mid-Atlantic shelf break (Mullin and Fulling, 2003;Garrison et al, 2010). Surveys did not extend far enough offshore to encounter deep-diving species, such as sperm and beaked whales, on a regular basis, although single sightings of both were recorded at the offshore limit of the study area.…”

“…Onslow Bay represents the southern limit of the range of common dolphins in the western North Atlantic (Waring et al, 2011); it is possible that this limit moves latitudinally in response to environmental variables, so that common dolphins are present in the study area during some years, but not others. Common dolphins were not observed in the broad-scale surveys of the South Atlantic Bight conducted in July and August 1998 by Mullin and Fulling (2003) but were recorded north of Cape Hatteras in June-August 2004 during the survey by Garrison et al (2010). The absence of spotted dolphins in the 1998-1999 surveys in Onslow Bay is puzzling.…”

“…In 2005, the US Navy proposed development of an Undersea Warfare Training Range (USWTR) in this area (Department of the Navy, 2009). Relatively little was known regarding the occurrence of cetaceans in the offshore waters of Onslow Bay because most previous surveys in the South Atlantic Bight had been conducted at a very coarse spatial scale (Mullin and Fulling 2003;Garrison et al 2010). To address this data limitation, an intensive survey programme was begun in June 2007.…”

“…1). A variety of cetaceans were known or believed to occur in this area, including shelf-associated species such as Atlantic spotted dolphins (Stenella frontalis) and common bottlenose dolphins (Tursiops truncatus) and pelagic species, such as short-finned pilot whales (Globicephala macrorhynchus) (Mullin and Fulling, 2003;Garrison et al, 2010). In addition, several mysticetes, such as endangered North Atlantic right whales (Eubalaena glacialis), likely use portions of Onslow Bay as a migratory corridor (Schick et al, 2009).…”

Short‐finned pilot whales in the South China Sea: Insights into regional distribution, movement pattern, and habitat characteristics

“…Short‐finned pilot whales, henceforth referred to as “pilot whales,” are well known as deep‐diving odontocetes because they can perform deep dives to common depths of 100–800 m for foraging, with maximum recorded dive depth of >1,000 m (Alves et al, 2013b; Quick et al, 2017; Shearer et al, 2022; Soto et al, 2008). Pilot whales typically inhabit continental shelf break (García Aguilar et al, 2021; Thorne et al, 2017), continental slope (Davis et al, 1998; Garrison et al, 2010), oceanic archipelago (Alves et al, 2013a; Hill et al, 2019; Servidio et al, 2019), and deep environments with high topographic relief (Abecassis et al, 2015; Kanaji et al, 2015). Such preference is usually due to enhanced primary productivity and abundant food resources such as squids and other cephalopods in the regions listed above (Boran & Heimlich, 2019; Stepanuk et al, 2018).…”