Having a whale of a time
Down in Nouvelle Caledonie (New Caledonia), the endangered humpback whales have adopted a tactic that has served them well in navigating across the vast Pacific expanse. This is a
novel migratory pattern that involves stop-overs at sea mounts and similar geographical shallows where some advantage must be attached to the locations. Claire Garrigue of Opération Cétacés in Nouméa and four colleagues from Perpignan, Rio and Washington and Seattle have related their discoveries in the Royal Society s Open Science journal today. The title is
Satellite tracking reveals novel migratory patterns and the importance of seamounts for endangered South Pacific humpback whales.
34 whales were tracked by satellite for from 5 to 110 days with one travelling 8540km as they migrated south in the annual migration from the south of the New Caledonia.. The unusual offshore and until now
cryptichangouts,landmarks, or feeding spots for a picnic of krill?
Free-ranging marine vertebrates have always been a problem for scientists. However, conservation management is now such a priority that every piece of information on habitat helps understanding of a particular niche. Megaptera novaeangliae at least in
nouvellecaledonie (!!!) uses sea mounts instead of its customary coastal habitat. The often-enormous mountains involved rise at least 100m from the seafloor and form one the earths largest biomes, with a strong influence on life cycles of smaller species, and now it seems the largest of creatures. Other whales have been observed to use them frequently and the humpback could well be doing so elsewhere.
13 females with calves, 8 other ladies and 26 males were tagged, with 13 failures recorded. Males travelled quicker than females, whether with or without the young. Direction was often but not inevitably S or SE. West was popular with a minority, the attraction being the Coral Sea and/or the Chesterfield Reef Complex. Some of the prominent seamounts used include Antigonia, Wanganella Pin, La Torche knoll and the Capel Seamount. Just try finding those on a map. Norfolk and Raoul Islands may be easier for you to find, but the whales would have learnt the way from their mothers early in life.
Behaviour at the seamounts was characterised by erratic slow movement, and indications that the animal had decide not to simply pass though, but to stay a-while (often >7 days, but up to 22.5 days). Similar attitudes prevailed during the breeding season in New Caledonia. Normally whales migrate in a straight and narrow (up to 800km wide) path, without such stopovers. This new discovery could help us understand much more about possible breeding grounds (eg. The Chesterfield Reef Complex previously mentioned.) The North Pacific is another region with significant seamounts that could be used by the resident humpbacks as unexpected breeding sites. The almost recreational use of seamounts in the south resembles a multi-purpose behavioural purpose in visits that offers researchers further scope for intimate and necessary discoveries on the habits of several species of whale, whether endangered or not.
We have so many articles describing humpbacks that well simply leave our encyclopaedias reference here, while more papers over recent years are described if you simply search in our panel.