[MARMAM] population spatial structure in humpback whales

peter at hwdt.org peter at hwdt.org
Wed Sep 27 02:07:25 PDT 2006

The following paper has recently been published online on Blackwell Synergy
and will appear in the next print issue of the Journal of Zoology. PDFs are
available on request. 
Peter Stevick
peter at hwdt.org

Stevick, PT, J Allen, PJ Clapham, SK Katona, F Larsen, J Lien, DK Mattila, PJ
Palsboll, R Sears, J Sigurjonsson, TD Smith, G Vikingsson, N Oien and PS
Hammond. Population spatial structuring on the feeding grounds in North
Atlantic humpback whales. Journal of Zoology, London. 270:244-255.

Population spatial structuring among North Atlantic humpback whales Megaptera
novaeangliae on the summer feeding grounds was investigated using movement
patterns of identified individuals. We analysed the results from an intensive
2-year ocean-basin-scale investigation resulting in 1658 individuals
identified by natural markings and 751 individuals by genetic markers
supplemented with data from a long-term collaborative study with 3063
individuals identified by natural markings. Re-sighting distances ranged from
<1km to >2200km. The frequencies (F) of resighting distances (D) observed in
consecutive years were best modelled by an inverse allometric function
(F=6631D-1.24, r2=0.984), reflecting high levels of site fidelity (median
re-sighting distance <40km) with occasional long-distance movement (5% of
re-sightings >550 km). The distribution of re-sighting distances differed east
and west of 51W, with more long-distance movement in the east. This difference
is consistent with regional patterns of prey distribution and predictability.
Four feeding aggregations were identified: the Gulf of Maine, eastern Canada,
West Greenland and the eastern North Atlantic. There was an exchange rate of
0.98% between the western feeding aggregations. The prevalence of
long-distance movement in the east made delineation of possible additional
feeding aggregations less clear. Limited exchange between sites separated by
as little as tens of kilometres produced lower-level structuring within all
feeding aggregations. Regional and temporal differences in movement patterns
reflected similar foraging responses to varying patterns of prey availability
and predictability. A negative relationship was shown between relative
abundance of herring and sand lance in the Gulf of Maine and humpback whale
movement from the Gulf of Maine to eastern Canada.

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