Section 7 Species Presence Information: Giant Manta Rays in the Greater Atlantic Region
Information on giant manta ray presence in the New England/Mid-Atlantic area for Section 7 consultations.
Note: Due to their rare occurrence mainly offshore within the Greater Atlantic Region, the giant manta ray is not included in our Species Tables or Section 7 Mapper. When considering whether to include an analysis of manta rays in your consultation request, please see the giant manta ray information below and also the Southeast Region’s Consultation Framework.
Giant manta rays (Mobula birostris) inhabit tropical, subtropical, and temperate bodies of water and are commonly found offshore in oceanic waters and near productive coastlines (i.e., surface thermal fronts, bathymetric slope, shelf-edge upwelling zones, and high chlorophyll-a concentration) (Marshall et al. 2009; Kashiwagi et al. 2011). The giant manta ray is considered to be a migratory species, with estimated distances of up to 1,500 kilometers traveled (Miller and Klimovich 2017). However, there is some evidence that giant manta rays may exist as well-structured subpopulations that exhibit a high degree of residency (Stewart et al. 2016b). Giant manta rays exhibit a high degree of variability in terms of their use of depths within their habitat, with tagging studies evidencing night descents of 200-450 meters (Rubin and Kumli 2008; Stewart et al. 2016a) and occasional dives to depths exceeding 1,000 meters (Miller and Klimovich 2017).
In terms of range in the eastern United States, the species has been documented as far north as offshore around the Hudson Canyon region near Long Island, New York (Gudger 1922; Kashiwagi et al. 2010; CITES 2013; Normandeau Associates and APEM Ltd 2017; as cited in 84 FR 66652). Farmer et al. (2022) integrated decades of sightings and survey effort data from multiple sources in a comprehensive species distribution-modeling framework to evaluate the distribution of giant manta rays off the U.S. east coast. The highest concentration of the over 5,000 sightings from 1925 to 2020 was in nearshore to shelf-edge waters off Florida and Georgia and nearshore and shelf-edge waters from Cape Hatteras north to New York (Farmer et al. 2022; Table 1). In New York, despite comprehensive coast to shelf survey coverage, manta sightings were exclusively in August on the continental shelf edge. While the modeling done by Farmer et al. 2022 predicted high numbers of manta rays in the Chesapeake and Delaware Bays due to the favorable habitat there (high chlorophyll-a concentrations associated with terrestrial outflow), there have been no reported sightings in these areas.
Farmer et al. (2022) determined that manta ray occurrence in the eastern US is influenced primarily by temperature, with a clear expansion to the north during warmer months and within this thermal range. They can be found in cool water, as low as 19 °C, although temperature preference appears to vary by region (approximately 20-30°C) (Duffy and Abbott 2003; Marshall et al. 2009; Freedman and Roy 2012; Graham et al. 2012). Models predicted highest nearshore occurrence off northeastern Florida during April, with the distribution extending northward along the shelf-edge as temperatures warm, leading to higher occurrences north of Cape Hatteras, North Carolina from June to October, and then south of Savannah, Georgia from November to March as temperatures cool. The vast majority (82%) of sightings north of 35° N were recorded from June to September.
Bycatch of giant manta rays in the northwest Atlantic Ocean has been observed in purse-seine, trawl, gillnet, and longline fisheries. However, as noted in a study by Oliver et al. (2015), as cited in Miller and Klimovich (2017), giant manta rays do not appear to be a significant component of the fisheries bycatch.
To view the full references, see Citations and References for All Species.