Carnegie Ridge, Galapagos to Mainland IMMA

Size in Square Kilometres

459 869 km2

Qualifying Species and Criteria

Blue whale – Balaenoptera musculus

Criterion A; C (2, 3)

Sperm Whale – Physeter macrocephalus

Criterion A; C (2, 3)

Marine Mammal Diversity 

Balaenoptera edeni, Delphinus delphis, Megaptera novaeangliae, Mesoplodon peruvianus, Orcinus orca, Pseudorca crassidens, Stenella attenuata

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The Carnegie Ridge forms a natural seaway between the eastern Galapagos Archipelago and the coasts of Ecuador (0°) and Peru (5°S), including the Gulf of Guayaquil. Geologically, the Carnegie Ridge structure comprises an area approximately 1,350 km long and 300 km wide. It was created by the passage of the Nazca Continental Plate over the Galapagos hotspot subducted beneath the Ecuador Andes. This area is permanently influenced by the Equatorial Front between the equator and 5°S, a shallow oceanographic feature that further fluctuates seasonally, probably controlled by winds, that increases regional productivity between the Galapagos and the mainland. The Carnegie Ridge serves as a migratory route between feeding and calving areas for various species of large whales. Most notably by Endangered blue whales (Balaenoptera musculus) and Vulnerable sperm whales (Physeter macrocephalus). The IMMA encompasses highly productive coastal and oceanic upwelling areas adjacent to the Galapagos archipelago and the Gulf of Guayaquil. These productive waters comprise important feeding habitat for blue, sperm, Bryde’s (Balaenoptera edeni), and humpback whales (Megaptera novaeangliae), as well as the pygmy beaked whale (Mesoplodon peruvianus).

Description of Qualifying Criteria

Criterion A – Species or Population Vulnerability

Blue whales are currently listed as Endangered on the IUCN Red List of Threatened Species (Cooke, 2018). Blue whales were once abundant in the Southern Hemisphere but were intensely exploited by industrial whaling that began in 1904 (Branch et al., 2004). In the South Pacific there were widespread catches along the west coast of South America north of 44°S off Chile, Peru, and Ecuador, and from Peru to the Galapagos Islands but no other catches north of 59°S in the waters stretching west to 180° (Branch et al., 2007). Pre-whaling abundance of southeast Pacific blue whales has been estimated at 1,500-5,000 individuals but the abundance in 1998 was estimated to be just above 12% of pre-whaling levels, based on minimum abundance estimates (Williams et al., 2011, 2017). Recent abundance estimates for Chilean blue whales in Chile and for the northern Chilean Patagonia feeding ground, provide remarkably similar results: 303 whales (95% CI 176–625) (Williams et al., 2011) and 373 whales (95% CI 191–652) (Bedriñana‐Romano et al., 2018), respectively. A third study based on different photo-id data sets yielded higher estimates, ranging between 569 (95% CI = 455-683), and 761 (95% CI = 614-908) (Galletti-Vernazzani et al., 2017). Uncertainty envelopes overlap across all recent studies and are indicative of a population ranging from low to mid hundreds. Due to the low population size of this blue whale subspecies/population, for which estimated potential biological removal (PBR) should not exceed 0.548 individuals per year, or one human-caused death in every 1.8 years (Bedriñana-Romano et al., 2018).

Sperm whales are currently listed as Vulnerable on the IUCN Red List of Threatened Species (Taylor et al., 2019).The current global estimated abundance of 360,000 individual whales represents an estimated 67% reduction from the initial pre-whaling population size (Whitehead, 2002). Historic whaling in the 19th century in the southeast Pacific including within the coastal waters of Peru and Ecuador caused severe declines of sperm whales in the region (Eguiguren et al., 2020). The eastern Pacific population was estimated to include 22,666-26,053 individuals (Wade and Gerrodette, 1993; Whitehead, 2002). There is no evidence that population has increased in recent years (Taylor et al., 2019). Sperm whales have been regularly documented in the Carnegie Ridge area, and from the Galapagos Archipelago to the Gulf of Guayaquil (Whitehead et al., 1997; Hamilton et al., 2008; Whitehead, 2011).

Criterion C: Key Life Cycle Activities

Sub-criterion C2: Feeding Areas

Although blue whales typically migrate between tropical breeding grounds and high latitude feeding grounds, some individuals may reside year-round in habitats of high productivity feeding on zooplankton, while others may stop to feed in areas of high productivity on route (Cooke, 2018). Multiple sightings of blue whales in this IMMA (Hamilton et al., 2008; CPPS/PNUD, 2012; Guzman pers. obser.) indicate that the area is used by blue whales, and data on productivity and whale behaviour during the time of observations indicate that the Carnegie Ridge encompasses feeding areas off the coast of mainland Ecuador (Gulf of Guayaquil) as well around the eastern Galapagos islands (CPPS/PNUD, 2012). In particular, Southern Hemisphere blue whales that occur off Ecuador and the Galapagos Islands, mostly during the austral winter, seem to be foraging in the area (Palacios, 1999; Busquete-Vass et al., 2021). Similarly to blue whales, Sperm whales have been reported feeding along the Carnegie Ridge, from the Galapagos Islands and mainland Ecuador (Whitehead, 1989; Whitehead, 2011; CPPS/PNUD, 2012; Eguiguren et al., 2021).

Sub-criterion C3: Migration Routes

At the global level there is evidence that most blue whales migrate between separate  wintering and summering areas (Hucke-Gaete et al., 2004; Cooke, 2018; Torres et al., 2015). Blue whale populations in the northeast Pacific and the eastern tropical pacific seem to be largely spatially and temporally separated (Reilly and Thayer, 1990; Ballance et al., 2006; Hamilton et al., 2009; Busquets-Vass et al., 2021).  There is evidence that blue whales that use the eastern tropical pacific further migrate north from Chile to the Galapagos and close to the mainland in and around the Gulf of Guayaquil (CPPS/PNUD, 2012; Hucke-Gaete et al., 2018). Recent data on sperm whale distribution and habitat use around the Galapagos suggest that whales use the Carnegie Ridge as migratory corridor from offshore areas to mainland areas between Northern Peru to Panama (CPPS/PNUD, 2012; Whitehead et al., 2008; Eguiguren et al., 2021). Movements determined by focal follows and re-sightings of photo-identified individuals indicate that movement patterns vary with gender and age, ranging from 2,000 to 5,000 km, with no reports of transoceanic movements between the eastern and western Pacific (Whitehead et al., 2008).

Supporting Information

Acuerdo Ministerial. 2017. Crea la Red de Areas Protegidas y Costeras Protegidas de Ecuador. Acuerdo Presidensial No. 30, 6 p.

Bedriñana-Romano, L., Hucke-Gaete, R., Viddi F.A., Morales, J., Williams, R., Ashe, E., Garcés-Vargas, J., Torres-Florez, J.P. and Ruiz, J. 2018. Integrating multiple data sources for assessing blue whale abundance and distribution in Chilean Northern Patagonia. Diversity & Distributions 2018; 00:1–14. 

Branch, T.A., Matsuoka, K. and Miyashita, T. 2004. Evidence for increases in Antarctic blue whales based on Bayesian modelling. Marine Mammal Science, 20, 726–754.

Branch, T.A., Stafford, K.M., Palacios, D.M., Allison, C., Bannister, J.L., Burton, C.L.K., Cabrera, E., Carlson, C., Galletti Vernazzani, B., Gill, P.C., Hucke-Gaete, R., Jenner, K.C.S., Jenner, M-N.M., Matsuoka, K., Mikhalev, Y.A., Miyashita, T., Morrice, M.G., Nishiwaki, S., Sturrock, V.J., Tormosov, D., Anderson, R.C., Baker, A.N., Best, P.B., Borsa, P., Brownell Jr., R.L., Childerhouse, S., Findlay, K.P., Gerrodette, T., Ilangakoon, A.D., Joergensen, M., Kahn, B., Ljunglad, D.K., Maughn, B., McCauley, R.D., McKay, S., Norris, T.F., Oman Whale And Dolphin Research Group,  Rankin, S., Samaran, F., Thiele, D., Van Waerebeek, K. and Warneke, R.M. 2007. Past and present distribution, densities and movements of blue whales Balaenoptera musculus in the Southern Hemisphere and northern Indian Ocean. Mammal Review 37: 116-175. 

Bourgois, J., 2013. A review on tectonic record of strain buildup and stress release across the Andean forearc along the Gulf of Guayaquil-Tumbes basin (GGTB) near Ecuador-Peru border. International Journal of Geosciences, 4, pp.618-635.

Busquets-Vass, G., Newsome, S.D., Pardo, M.A., Calambokidis, J., Aguíñiga-García, S., Páez-Rosas, D., Gómez-Gutiérrez, J., Enríquez-Paredes, L.M. and Gendron, D., 2021. Isotope-based inferences of the seasonal foraging and migratory strategies of blue whales in the eastern Pacific Ocean. Marine Environmental Research, 163, p.105201.

Chavez, F.P. and Brusca, R.C., 1991. The Galapagos Islands and their relation to oceanographic processes in the tropical Pacific. In Galapagos marine invertebrates (pp. 9-33). Springer, Boston, MA.

Cooke, J.G. & Brownell Jr., R.L. 2018. Balaenoptera edeni. The IUCN Red List of Threatened Species 2018: e.T2476A50349178. Accessed on 09 June 2022.

Cooke, J.G. 2018. Megaptera novaeangliae. The IUCN Red List of Threatened Species 2018: e.T13006A50362794. Accessed on 09 June 2022.

CPPS/PNUMA. 2012. Atlas sobre distribución, rutas migratorias, hábitats críticos y amenazas para grandes cetáceos en el Pacífico oriental. Comisión Permanente del Pacífico Sur – CPPS / Programa de las Naciones Unidas para el Medio Ambiente – PNUMA. Guayaquil, Ecuador. 75p.

de La Torre, G.M. and Macnab, R., 2005. December. Carnegie Ridge: A natural prolongation of the Galapagos Platform. In AGU Fall Meeting Abstracts (Vol. 2005, pp. T13D-0506).

Eguiguren, A., Pirotta, E., Boerder, K., Cantor, M., Merlen, G. and Whitehead, H., 2021. Historical and contemporary habitat use of sperm whales around the Galapagos Archipelago: Implications for conservation. Aquatic Conservation: Marine and Freshwater Ecosystems, 31(6), pp.1466-1481.

Galletti-Vernazzani, B., Jackson, J.A., Cabrera, E., Carlson, C.A. and Brownell Jr. R.L. 2017. Estimates of Abundance and Trend of Chilean blue whales off Isla de Chiloé, Chile. PLoSONE 12(1): e0168646 doi:10.1371/journal.pone.0168646

Graindorge, D., Calahorrano, A., Charvis, P., Collot, J.Y. and Bethoux, N., 2004. Deep structures of the Ecuador convergent margin and the Carnegie Ridge, possible consequence on great earthquakes recurrence interval. Geophysical Research Letters, 31(4).

Gutscher, M.A., Malavieille, J., Lallemand, S. and Collot, J.Y., 1999. Tectonic segmentation of the North Andean margin: impact of the Carnegie Ridge collision. Earth and Planetary Science Letters, 168(3-4), pp.255-270.

Hamilton, T.A., Redfern, J.V., Barlow, J., Ballance, L.T., Gerrodette, T., Holt, R.S., Forney, K.A,  and B.L. Taylor. 2008. Atlas of Cetacean sightings from Southwest Fisheries Science Center Cetacean and Ecosystem Surveys : 1986-2005. NOAA Technical Memorandum NMFS, NOAA-TM-NMFS-SWFSC-440.

Hucke-Gaete, R., Osman, L.P., Moreno, C.A., Findlay, K.P. and Ljungblad, D.K., 2004. Discovery of a blue whale feeding and nursing ground in southern Chile. Proceedings of the Royal Society of London. Series B: Biological Sciences, 271(suppl_4), pp.S170-S173.

Hucke-Gaete, R., Bedrinana-Romano, L., Viddi, F.A., Ruiz, J.E., Torres-Florez, J.P. and Zerbini, A.N., 2018. From Chilean Patagonia to Galapagos, Ecuador: novel insights on blue whale migratory pathways along the Eastern South Pacific. PeerJ, 6, p.e4695.

Leduc, R.G., Archer, F.I., Lang, A.R., Martien, K.K., Hancock‐Hanser, B., Torres‐Florez, J.P., Hucke‐Gaete, R., Rosenbaum, H.C., Van Waerebeek, K., Brownell Jr, R.L. and Taylor, B.L., 2017. Genetic variation in blue whales in the eastern pacific: Implication for taxonomy and use of common wintering grounds. Molecular Ecology, 26(3), pp.740-751.

Lynner, C., Koch, C., Beck, S.L., Meltzer, A., Soto-Cordero, L., Hoskins, M.C., Stachnik, J.C., Ruiz, M., Alvarado, A., Charvis, P. and Font, Y., 2020. Upper-plate structure in Ecuador coincident with the subduction of the Carnegie Ridge and the southern extent of large mega-thrust earthquakes. Geophysical Journal International, 220(3), pp.1965-1977.

Montecino, V. and Lange, C.B., 2009. The Humboldt Current System: Ecosystem components and processes, fisheries, and sediment studies. Progress in Oceanography, 83(1-4), pp.65-79.

Pak, H. and Zaneveld, J.R.V., 1974. Equatorial front in the eastern Pacific Ocean. Journal of Physical Oceanography, 4(4), pp.570-578.

Palacios, D.M., 2002. Factors influencing the island‐mass effect of the Galápagos Archipelago. Geophysical Research Letters, 29(23), pp.49-1.

Palacios, D.M., 2004. Seasonal patterns of sea-surface temperature and ocean color around the Galápagos: regional and local influences. Deep Sea Research Part II: Topical Studies in Oceanography, 51(1-3), pp.43-57.

Pitman, R.L. and Lisa T. Balance. 2022. Thoughts on Important Marine Mammal Areas in the Eastern Tropical Pacific. Marine Mammal Institute, Oregon State University, USA.

Pitman, R.L. & Taylor, B.L. 2020. Mesoplodon peruvianus. The IUCN Red List of Threatened Species 2020: e.T13251A50367335. Accessed on 09 June 2022.

Redfern, J.V., Moore, T.J., Fiedler, P.C., de Vos, A., Brownell Jr, R.L., Forney, K.A., Becker, E.A. and Ballance, L.T., 2017. Predicting cetacean distributions in data‐poor marine ecosystems. Diversity and Distributions, 23(4), pp.394-408.

Reyes, J.C., 2018. The Lesser beaked whale Mesoplodon peruvianus Reyes, Mead & Van Waerebeek 1991 revisited, with biological observations on new specimens from Peru. J Mar Biol Oceanogr 7, 4, p.2.

Shumway, G., 1954. Carnegie ridge and cocos ridge in the East Equatorial Pacific. The Journal of Geology, 62(6), pp.573-586.

Stevenson, M.R. and Taft, B.A., 1971. New evidence of the Equatorial Undercurrent east of the Galapagos Islands. J. Mar. Res, 29(2), pp.103-115.

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Torres-Florez, J.P., Olson, P.A., Bedriñana-Romano, L., Rosenbaum, H., Ruiz, J., LeDuc, R. and Hucke-Gaete, R., 2015. First documented migratory destination for eastern South Pacific blue whales. Marine Mammal Science, 31(4), pp.1580-1586.

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Williams, R., Hedley, S., Branch, T.A., Bravington, M., Zerbini, A.N. and Findlay K. 2011. Chilean blue whales as a case study to illustrate methods to estimate abundance and evaluate conservation status of rare species. Conservation Biology 25:526-535.

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Whitehead, H., Christal, J. and Dufault, S., 1997. Past and distant whaling and the rapid decline of sperm whales off the Galapagos Islands. Conservation Biology, 11(6), pp.1387-1396.

Whitehead, H., 1999. Variation in the visually observable behavior of groups of Galápagos sperm whales. Marine Mammal Science, 15(4), pp.1181-1197.

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