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Author Topic: Are whale strandings a method of population control?  (Read 1359 times)

Offline Sciencemd68

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In the US and New Zealand, there seems to be an increase in whale stranding events recently. It seems curious to me that the only animals involved in these stranding events rely heavily on squid for resources. (pilot whales, sperm whales, dolphins, etc. ) No baleen whales are known to strand en mass. There has been alot of research to identify a cause such as acoustic trauma, infectious disease, acoustic confusion, and geomagnetic implications; yet none of these explains all these events. One researcher from New Zealand found a  11-13 year periodocity of these mass stranding events which coorelates well with our sun's own cycle of thermal variability. Furthermore, if you look at the squid biomass from year to year, (see attachment) it is widely variable. These animals are all long lived, communal, and have little to no historic predation which makes them vulnerable to overpopulation. Could stranding be an adaptation to keep numbers at or below sustainability for those years when squid numbers are very low? If these pods expanded during times of plenty, they would be vulnerable to mass extinction during times of dearth.  Not exactly mass suicide per se, but nonetheless, whatever is driving these stranding events is not selected out because it has meant improved survival for those pods with the stranding allele in the gene pool. (Similiar to the way the allele for sickle cell disease is maintained in an area of endemic malaria.) A book entitled The Ju-jitsu of the Peahen expands on this theme and is interesting reading.
« Last Edit: 08/02/2012 21:40:44 by chris »


Offline Don_1

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Re: Whale strandings
« Reply #1 on: 08/02/2012 14:01:26 »
..... Could stranding be an adaptation to keep numbers at or below sustainability for those years when squid numbers are very low?

I very seriously doubt that this would be the case. I can think of no evolutionary benefit to mass suicide.

The toothed whales do have predators. The Orca and larger sharks are known to attack whales, though the incidence in admittedly low.

The beaching of an individual could be health related. A sick whale might seek refuge in shallow water to avoid the possibility of drowning.

En mass beaching, to my mind, is possibly the result of feeding, where the prey seek refuge in shallow waters. The whales, chasing the prey inadvertently find themselves in these shallows just as the tide is receding and are unable to return to deeper water. Their intended prey, on the other hand, can still do so. This would only be the case for the toothed whales. The baleen whales, feeding on krill, would not find their prey making for a shallow water haven.

But this is just one of a number of suggested causes, none of which can be established as being the sole cause of such sad events. In some cases, marine conservationists and concerned helpers have managed to get some of these animals back into deeper waters before they are left high and dry. This suggests to me that there was no intent to beach.

For now, and possibly forever, the cause of these heartbreaking events must remain a mystery. Every possible explanation is worthy of consideration, especially those which are the cause of man's interference.

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Re: Whale strandings
« Reply #1 on: 08/02/2012 14:01:26 »


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