Crozet Islands IMMA
Size in Square Kilometres
244,650 km2
Qualifying Species and Criteria
Killer whale – Orcinus orca
Criterion C (2); D (1)
Southern elephant seal – Mirounga leonina
Criterion C (1)
Antarctic fur seal – Arctocephalus gazella
Criterion C (1)
Subantarctic fur seal – Arctocephalus tropicalis
Criterion C (1)
Marine Mammal Diversity
Physeter macrocephalus, Balaenoptera musculus intermedia,
Balaenoptera musculus brevicauda
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Summary
The Crozet Islands archipelago comprises five islands that fall under French territorial jurisdiction. The IMMA includes the Crozet Plateau, on which the islands lie, as well as the Del Cano Rise to the northwest of the islands, extending to roughly the 2000m contour. From 2006 onward these islands and their surrounding waters form part of the French Natural Reserves (Biological Integral Reserves), administered by the French Ministry of the Terres Australes and Antarctique Françaises. The islands serve as breeding, moulting and feeding areas for Antarctic fur seals (Arctocephalus gazella), subantarctic fur seals (A. tropicalis) and southern elephant seals (Mirounga leonina).
The area also hosts at least two different populations of killer whales (Orcinus orca). The Crozet type population is thought to be related to Type A killer whales, while members of the genetically divergent D-type have also been recorded. Killer whales in the area prey on Patagonian toothfish (Dissostichus eleginoides), and have been observed interacting with the longline fishery for this species.
Description of Qualifying Criteria
Criterion C: Key Life Cycle Activities
Sub-criterion C1: Reproductive Areas
The Subantarctic fur seal population in the Crozet Islands increased during the 1980s and 1990s, stabilized in the late 2000s, but has been decreasing since then. Pup production at Île de la Possession (205 pups) probably represents less than 0.1% of the global pup production. The small Antarctic fur seal population (472 pups) accounts for less than 0.1% of the global population (assuming one pup to represent an adult female).
The southern elephant seal population is currently stable but experienced major declines in the 1960s and 1970s (up to 80% population decline). The elephant seal population of the whole Crozet Islands archipelago is estimated to be around 8,000-12,000 individuals (C. Guinet, pers. comm.), which represents around 1-2% of the global population. The decrease could be due to an environmental regime shift and strong predation pressure from killer whales (Guinet et al. 1999).
Sub-criterion C2: Feeding Areas
At-sea sightings of killer whales in the Crozet Islands archipelago are made from longline fishing vessels, and are therefore biased towards fishing areas, however the sightings are concentrated along the 1000 m depth contour delineating the Crozet Plateau and sightings also occur on the Del Cano Rise to the north west of the Crozet Plateau (Tixier et al. 2016). While killer whales are attracted to fishing vessels operating in the candidate area, recent stable isotope analyses (Reisinger et al. 2016, Tixier et al. 2019) and dive data (Reisinger et al. 2015, Towers et al. 2019) indicates that Patagonian toothfish are not only depredated by killer whales from fishing vessels, but are also their natural prey. Therefore, the plateau edge, the Del Cano Rise and various seamounts, which are profitable fishing areas, likely also represent key natural foraging sites for killer whales independently of the presence of fishing vessels. Killer whales patrol the inshore waters where they feed on seals and penguins (Guinet 1991, 1992).
Criterion D: Special Attributes
Sub-criterion D1: Distinctiveness
Two different populations of killer whales occur in Crozet waters, the Crozet type, thought to be related to Antarctic Type A killer whales (A.R. Hoelzel, unpublished data), and Type D killer whales. From 2003-2014, 129 individuals belonging to the Crozet type were photo-identified in Crozet EEZ (Tixier et al. 2014a) and 40 Type D killer whales were photo-identified (Tixier et al. 2014b). Type D killer whales are rarely observed, and little is known of their ecology, but they seem to have a circumpolar distribution in sub-Antarctic waters (Pitman et al. 2011). Mitogenome sequences indicate that Type D killer whales are highly divergent from any known killer whales and are probably a distinct species or subspecies (Foote et al. 2013).
Supporting Information
Branch, T.A., Stafford, K.M., Palacios, D.M., Allison, C., Bannister, J.L., Burton, C.L.K., Cabrera, E., Carlson, C.A., 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, R.L., Childerhouse, S., Findlay, K.P., Gerrodette, T., Ilangakoon, A.D., Joergensen, M., Kahn, B., Ljungblad, D.K., Maughan, B., McCauley, R.D., McKay, S., Norris, T.F., Rankin. S., Samaran, F., Thiele, D., Waerebeek, K.V., Warneke, R.M. 2007. Past and present distribution, densities and movements of blue whales Balaenoptera musculus in the Southern Hemisphere and northern Indian Ocean. Mamm Rev 37:116–175
Cooke, J.G. 2018. Balaenoptera musculus ssp. intermedia. The IUCN Red List of Threatened Species 2018: e.T41713A50226962. http://dx.doi.org/10.2305/IUCN.UK.2018-2.RLTS.T41713A50226962.en
Foote AD, Morin P a., Pitman RL, Ávila-Arcos MC, Durban JW, Helden A, Sinding M-HS, Gilbert MTP. 2013. Mitogenomic insights into a recently described and rarely observed killer whale morphotype. Polar Biol 36:1519–1523
Guinet C. 1991. L’Orque (Orcinus orca) autour de l’Archipel Crozet. Comparaison avec d’autres localites. Rev Ecol (Terre Vie) 46:321–337
Guinet C. 1992. Comportement de chasse des orques (Orcinus orca) autour des iles Crozet. Can J Zool 70:1656–1667
Guinet C, Jouventin P, Weimerskirch H. 1999. Recent population change of the southern elephant seal at Îles Crozet and Îles Kerguelen: the end of the decrease? Antarct Sci 11:193–197
Janc A, Richard G, Guinet C, Arnould JPY, Villanueva MC, Duhamel G, Gasco N, Tixier P. 2018. How do fishing practices influence sperm whale (Physeter macrocephalus) depredation on demersal longline fisheries? Fish Res 206:14–26
Labadie G, Tixier P, Barbraud C, Fay R, Gasco N, Duhamel G, Guinet C. 2018. First demographic insights on historically harvested and poorly known male sperm whale populations off the Crozet and Kerguelen Islands (Southern Ocean). Mar Mammal Sci:1–21
Leroy EC, Samaran F, Bonnel J, Royer JY. 2016. Seasonal and diel vocalization patterns of Antarctic blue whale (Balaenoptera musculus intermedia) in the Southern Indian Ocean: A multi-year and multi-site study. PLoS One 11:1–20
Leroy EC, Samaran F, Stafford KM, Bonnel J, Royer JY. 2018. Broad-scale study of the seasonal and geographic occurrence of blue and fin whales in the Southern Indian Ocean. Endanger Species Res 37:289–300
Pitman RL, Durban JW, Greenfelder M, Guinet C, Jorgensen M, Olson P a., Plana J, Tixier P, Towers JR. 2011. Observations of a distinctive morphotype of killer whale (Orcinus orca), type D, from subantarctic waters. Polar Biol 34:303–306
Reisinger R, Gröcke D, Lübcker N, McClymont E, Hoelzel A, Bruyn P de. 2016. Variation in the diet of killer whales Orcinus orca at Marion Island, Southern Ocean. Mar Ecol Prog Ser 549:263–274
Reisinger RR, Keith M, Andrews RD, Bruyn PJN de. 2015. Movement and diving of killer whales (Orcinus orca) at a Southern Ocean archipelago. J Exp Mar Bio Ecol 473:90–102
Samaran F, Adam O, Guinet C. 2010. Discovery of a mid-latitude sympatric area for two Southern Hemisphere blue whale subspecies. Endanger Species Res 12:157–165
Samaran F, Stafford KM, Branch TA, Gedamke J, Royer JY, Dziak RP, Guinet C. 2013. Seasonal and Geographic Variation of Southern Blue Whale Subspecies in the Indian Ocean. PLoS One 8
Tixier P, Gasco N, Duhamel G, Guinet C. 2016. Depredation of Patagonian toothfish (Dissostichus eleginoides) by two sympatrically occurring killer whale (Orcinus orca) ecotypes: Insights on the behavior of the rarely observed type D killer whales. Mar Mammal Sci 32:983–1003
Tixier P, Gasco N, Guinet C. 2014a. Killer whales of the Crozet islands, photo-identification catalogue 2003-2011. DOI: https://doi.org/10.6084/m9.figshare.1085960.v1
Tixier P, Gasco N, Poupart T, Guient C. 2014b. Type-D killer whales of the Crozet Islands. Photo-Identification Catalogue 2014. DOI: https://doi.org/10.6084/m9.figshare.1060259.v2
Tixier P, Giménez J, Reisinger R, Méndez-Fernandez P, Arnould J, Cherel Y, Guinet C. 2019. Importance of toothfish in the diet of generalist subantarctic killer whales: implications for fisheries interactions. Mar Ecol Prog Ser 613:197–210
Towers JR, Tixier P, Ross KA, Bennett J, Arnould JPY, Pitman RL, Durban JW. 2019. Movements and dive behaviour of a toothfish-depredating killer and sperm whale. ICES J Mar Sci 76:298–311
