South Atlantic Bight IMMA
Size in Square Kilometres
104 848 km2
Qualifying Species and Criteria
North Atlantic Right Whale – Eubalaena glacialis
Criterion A; Criterion B (2); Criterion C (1)
Common Bottlenose Dolphin- Tursiops truncatus
Criterion B (2)
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Summary
The South Atlantic Bight is located along the southeast coast of the United States. It covers the upper continental shelf from Cape Lookout, North Carolina to the eastern tip of Florida. The area spans the shoreline to the 150 m isobath, beyond which the Gulf Stream flows. It includes the Gray’s Reef National Marine Sanctuary, and importantly, also includes the Southeastern U.S. Calving Area Critical Habitat for North Atlantic right whales (Eubalaena glacialis), which encompasses the only known calving ground of this critically endangered species. North Atlantic right whales reliably aggregate here every year to give birth and socialize, with peak presence occurring from December through March. Small numbers of humpback whales (Megaptera novaeangliae) have also been observed overwintering during the same months since 2008, and large numbers of common bottlenose dolphins (Tursiops truncatus) and Atlantic spotted dolphins (Stenella frontalis) are found here throughout the year.
Description of Qualifying Criteria
Criterion A: Species or Population Vulnerability
The North Atlantic right whale (Eubalaena glacialis) is listed on the IUCN Red List as Critically Endangered (Cook 2020), with a median population estimate of 356 (+7/-10) individuals remaining in the population in 2022 (Linden 2023, Pettis and Hamilton 2024).
Criterion B: Distribution and Abundance
Sub-criterion B2: Aggregations
In the post-whaling era, the North Atlantic right whale population peaked around 2011 and has declined since that time (Pace et al. 2017; Pettis and Hamilton 2024). Before that 2011 peak, a substantial fraction of the population migrated to the calving ground every winter, including both adult and juvenile right whales of both sexes. This aggregation likely peaked in the winter of 2009/2010, during which the total population was estimated at 482 (Pettis and Hamilton 2024) and 220 individuals were observed at the calving ground, south of Cape Fear, North Carolina (Krzystan et al. 2018). During that year, 39 calves were recorded (Pettis and Hamilton 2024), but observations suggested even larger numbers of other demographic groups were present, including both non-calf juveniles and adult males (Krzystan et al. 2018). Thus, when the right whale population was growing, this calving ground represented an aggregation area not just for pregnant females and their calves, but for all segments of the population. For the period 1992–2001, Parks et al. (2007) documented 191 “surface active groups” in the area, during which right whales were probably engaged in mating, mating practice, play, or maintenance of social bonds. Since the population entered decline, the numbers of whale migrating to the calving ground has decreased (Gowan et al. 2019).
The IMMA also hosts aggregations of coastal bottlenose dolphins (Tursiops truncatus). These include the following stocks recognised by NOAA Fisheries: the western North Atlantic northern Florida coastal stock, the western North Atlantic central Florida coastal stock, and the western North Atlantic northern South Carolina/Georgia coastal stock (NOAA Fisheries). The best available abundance estimate for the Northern Florida Coastal Stock of common bottlenose dolphins in the western North Atlantic is 877 (CV=0.49), 1,218 (CV=0.35) for the central Florida coastal stock, and 6,027 (CV=0.34) for the South Carolina/Georgia Coastal Stock (Garrison et al., 2017). Estimates were inferred from aerial surveys conducted from New Jersey to Florida during the summer of 2016. While common bottlenose dolphins do exhibit significant site fidelity, it is unlikely this stock contains multiple demographically independent populations because the habitat used by the stock is relatively homogeneous, it does not cross any known biogeographic breaks nor cover multiple marine ecoregions (Spalding et al. 2007).
Criterion C: Key Life Cycle Activities
Sub-criterion C1: Reproductive Areas
The South Atlantic Bight IMMA contains the only known major calving ground for the North Atlantic right whale. It has been regularly monitored by aerial surveys since the 1990s and new calves have been observed every year except 2018 (Pettis and Hamilton 2024). Peak presence of mother/calf pairs occurs from December through March (Gowan et al. 2014; Krzystan et al. 2018; Gowan et al. 2019; Roberts et al. 2024). From 2009-2023, annual calf counts ranged from a low of 0 calves observed in 2018 to a high of 39 in 2009 (Pettis and Hamilton 2024). The low in 2018 followed an Unusual Mortality Event in 2017, in which 17 whales were documented to have died, with an estimate of over 40 actual deaths (Kenney 2018, Linden 2023). Calving has since rebounded to a post-2018 peak of 18 documented calves in 2021 (Pettis and Hamilton 2024). On the calving grounds, right whales are most likely to be sighted between northern Florida and Georgia, in cooler (12-16 °C) waters and intermediate (10-25 m) depths relatively close (<25 km) to shore (Gowan et al. 2014), but birth has been observed as far as 63 km from shore (Foley et al. 2011).
Supporting Information
Blanton, B.O., Aretxabaleta, A., Werner, F.E. and Seim, H.E., 2003. Monthly climatology of the continental shelf waters of the South Atlantic Bight. Journal of Geophysical Research: Oceans, 108(C8).
Cooke, J.G. 2020. Eubalaena glacialis (errata version published in 2020). The IUCN Red List of Threatened Species 2020: e.T41712A178589687. https://dx.doi.org/10.2305/IUCN.UK.2020-2.RLTS.T41712A178589687.en
Foley, H.J., Holt, R.C., Hardee, R.E., Nilsson, P.B., Jackson, K.A., Read, A.J., Pabst, D.A., McLellan, W.A., 2011. Observations of a western North Atlantic right whale (Eubalaena glacialis) birth offshore of the protected southeast U.S. critical habitat. Marine Mammal Science 27, E234–E240. https://doi.org/10.1111/j.1748-7692.2010.00452.x
Garrison, L.P., K. Barry and W. Hoggard. 2017. The abundance of coastal morphotype bottlenose dolphins on the U.S. east coast: 2002-2016. Southeast Fisheries Science Center, Protected Resources and Biodiversity Division, 75 Virginia Beach Dr., Miami, FL 33140. PRBD Contribution # PRBD-2017-01.
Gowan, T.A., Ortega-Ortiz, J.G., 2014. Wintering habitat model for the North Atlantic right whale (Eubalaena glacialis) in the southeastern United States. PLoS ONE 9, e95126. https://doi.org/10.1371/journal.pone.0095126
Gowan, T.A., Ortega-Ortiz, J.G., Hostetler, J.A., Hamilton, P.K., Knowlton, A.R., Jackson, K.A., George, R.C., Taylor, C.R., Naessig, P.J., 2019. Temporal and demographic variation in partial migration of the North Atlantic right whale. Sci Rep 9, 353. https://doi.org/10.1038/s41598-018-36723-3
Kenney, R.D., 2018. What if there were no fishing? North Atlantic right whale population trajectories without entanglement mortality. Endang. Species. Res. 37, 233–237. https://doi.org/10.3354/esr00926
Krzystan, A., Gowan, T., Kendall, W., Martin, J., Ortega-Ortiz, J., Jackson, K., Knowlton, A., Naessig, P., Zani, M., Schulte, D., Taylor, C., 2018. Characterizing residence patterns of North Atlantic right whales in the southeastern USA with a multistate open robust design model. Endangered Species Research 36, 279–295. https://doi.org/10.3354/esr00902
Linden, D. 2023. Population size estimation of North Atlantic right whales from 1990-2022. US Dept Commer Northeast Fish Sci Cent Tech Memo 314. 14 p.
Pace, R.M., III, Corkeron, P.J., Kraus, S.D., 2017. State-space mark-recapture estimates reveal a recent decline in abundance of North Atlantic right whales. Ecol Evol 7, 8730–8741. https://doi.org/10.1002/ece3.3406
Parks, S.E., Brown, M.W., Conger, L.A., Hamilton, P.K., Knowlton, A.R., Kraus, S.D., Slay, C.K., Tyack, P.L., 2007. Occurrence, Composition, and Potential Functions of North Atlantic Right Whale (Eubalaena Glacialis) Surface Active Groups. Marine Mammal Sci 23, 868–887. https://doi.org/10.1111/j.1748-7692.2007.00154.x
Pettis, H.M., Hamilton, P.K., 2024. North Atlantic Right Whale Consortium 2023 Annual Report Card. North Atlantic Right Whale Consortium, Boston, MA.
Roarty, H., Glenn, S., Brodie, J., Nazzaro, L., Smith, M., Handel, E., Kohut, J., Updyke, T., Atkinson, L., Boicourt, W., Brown, W., Seim, H., Muglia, M., Wang, H., Gong, D., 2020. Annual and seasonal surface circulation over the Mid-Atlantic Bight Continental Shelf derived from a decade of High Frequency Radar observations. J. Geophys. Res. Oceans 125, e2020JC016368. https://doi.org/10.1029/2020JC016368
Schick, R., Halpin, P., Read, A., Urban, D., Best, B., Good, C., Roberts, J., LaBrecque, E., Dunn, C., Garrison, L., Hyrenbach, K., McLellan, W., Pabst, D., Palka, D., Stevick, P., 2011. Community structure in pelagic marine mammals at large spatial scales. Mar Ecol Prog Ser 434, 165–181. https://doi.org/10.3354/meps09183
Roberts, J.J., Yack, T.M., Fujioka, E., Halpin, P.N., Baumgartner, M.F., Boisseau, O., Chavez-Rosales, S., Cole, T.V.N., Cotter, M.P., Davis, G.E., DiGiovanni Jr., R.A., Ganley, L.C., Garrison, L.P., Good, C.P., Gowan, T.A., Jackson, K.A., Kenney, R.D., Khan, C.B., Knowlton, A.R., Kraus, S.D., Lockhart, G.G., Lomac-MacNair, K.S., Mayo, C.A., McKenna, B.E., McLellan, W.A., Nowacek, D.P., O’Brien, O., Pabst, D.A., Palka, D.L., Patterson, E.M., Pendleton, D.E., Quintana-Rizzo, E., Record, N.R., Redfern, J.V., Rickard, M.E., White, M., Whitt, A.D., Zoidis, A.M., 2024. North Atlantic right whale density surface model for the U.S. Atlantic evaluated with passive acoustic monitoring. Mar Ecol Prog Ser 732, 167–192. https://doi.org/10.3354/meps14547
Spalding, M.D., H.E. Fox, G.R. Allen, N. Davidson, Z.A. Ferdaña, M. Finlayson, B.S. Halpern, M.A. Jorge, A. Lombana and S.A. Lourie. 2007. Marine ecoregions of the world: A bioregionalization of coastal and shelf areas. BioScience 57(7):573–583.
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