Joiris, C.R.

Open Marine Archive

129 
 
S03: Distribution and trends of top predators 
Hotspots in the distribution of the top predators – seabirds, 
cetaceans and pinnipeds – in polar marine ecosystems. 
Joiris Claude R.1, 2 
1 Laboratory for Polar Ecology (PolE), Ramillies, Belgium 
 E-mail: crjoiris@gmail.com  
2  Conservation Biology Unit, Royal Institute for Natural Sciences, Brussels, Belgium 
 
Observations of major hotspots in the at-sea distribution of top predators were tallied during recent 
years in both polar areas on board icebreaker RV Polarstern, Bremerhaven, Germany. They concern 
cetaceans: fin whale Balaenoptera physalus, humpback whale Megaptera novaeangliae, Southern 
right whale Eubalaena australis, as well as pinnipeds: crabeater seal Lobodon carcinophaga, harp 
seal Pagophilus groenlandica, Antarctic fur seal Arctocephalus gazella, and seabirds: grey-headed 
albatross Thalassarche chrysostoma, Southern fulmar Fulmarus glacialoides, little auk Alle alle, 
common and Brünnich’s guillemots Uria aalge and U. lomvia, Antarctic prion Pachyptila desolata 
and kittiwake Rissa tridactyla. Numbers tallied during a few 30min transect counts (i.e. a few tens 
nm) concerned can reach thousands of individuals and represent up to 98% of all individuals of the 
species tallied during the whole expedition. Selected examples of maximal numbers in limited areas 
are: 1,950 common guillemots out of a total of 1,975 and 133 humpback whales out of a total of 
149 (Joiris 2011), 304 fin whales out of 308, 6,945 grey-headed albatrosses out of 6,970 and 
76,800 southern fulmars out of 77,000 (Joiris & Dochy 2013), 2,000 crabeaters out of 2,260 (Joiris 
& D’Hert 2015). Moreover very local concentrations were encountered such as 1,500 little auks 
during 10min, i.e. less than 2 nm (Joiris et al. 2014). The hotspots were basically observed in 
autumn, often in areas visited by scientists mainly in summer and sometimes in winter, and located 
on or around icebergs. They often concern cetaceans, pinnipeds and seabirds at the same location 
(see higher). They can thus be considered reflecting post breeding and pre-migration gatherings 
and probably correspond to very high prey (krill) concentrations. Practical consequences are on the 
one hand that they lead to drastic underestimations of actual densities if undetected. On the other 
hand, such data should obviously not be included in density calculations. 
 
References 
- Joiris CR. submitted. Hotspot of kittiwakes Rissa tridactyla on icebergs off South-West Greenland 
in autumn.  
- Joiris CR and D’Hert D. 2015. Summer social structure by crabeater seal Lobodon carcinophaga in 
the Amundsen Sea, Antarctica. Polar Biology 39 (2016): 397-403. DOI: 10.1007/s00300-015-
1778-9. 
- Joiris CR, Humphries GRW, D’Hert D, Lafontaine R-M, Robert H and Beudels-Jamar RC. 2015. Major 
hotspots detected along the Scotia Ridge in autumn for southern right whales Eubalaena australis, 
Antarctic fur seals Arctocephalus gazella and Antarctic prions Pachyptila desolata. Advances in 
Polar Science 26: 282-291. DOI: 10.13679/j.advps.2015.4.00282. 
- Joiris CR, Falck E, D’Hert D, Jungblut S and Boos K. 2014. An important late summer aggregation 
of fin whales Balaenoptera physalus, little auks Alle alle and Brünnich’s guillemots Uria lomvia in 
the eastern Greenland Sea and Fram Strait: influence of hydrographic structures. Polar Biology 37: 
1645-1657. DOI: 10.1007/s00300-014-1551-5. 
- Joiris CR and Dochy O. 2013. A major autumn feeding ground for fin whales, southern fulmars 
and grey-headed albatrosses around the South Shetland Islands, Antarctica. Polar Biology 36: 
1649-1658. DOI: 10.1007/s00300-013-1383-8. 
- Joiris CR. 2011. A major feeding ground for cetaceans and seabirds in the south-western 
Greenland Sea. Polar Biology 34: 1597-1607. DOI: 10.1007/s00300-011-1022-1. 
- Joiris CR and Falck E. 2010. Summer at-sea distribution of little auks Alle alle and harp seals 
Pagophilus (Phoca) groenlandica in the Greenland Sea: impact of small-scale hydrological events. 
Polar Biology 34: 541-548 (2011). DOI: 10.1007/s00300-010-0910-0.  
  


Hotspots in the distribution of the top predators – seabirds, cetaceans and pinnipeds – in polar marine ecosystems

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