Are solar activity and sperm whale Physeter macrocephalus strandings around the North Sea related?
In: Journal of Sea Research. Elsevier/Netherlands Institute for Sea Research: Amsterdam; Den Burg. ISSN 1385-1101; e-ISSN 1873-1414, more
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| Keywords |
Anomalies > Magnetic anomalies
Aquatic organisms > Marine organisms > Aquatic mammals > Marine mammals
Environmental effects
Environmental factors > Anthropogenic factors
Magnetism > Geophysics > Geomagnetism
Solar activity
Solar cycles
Stranding
Physeter macrocephalus Linnaeus, 1758 [WoRMS]
ANE, North Sea [Marine Regions]
Marine/Coastal |
| Author keywords |
sperm whale strandings; North Sea; solar cycles; sun spots; geomagneticstorms |
| Authors | | Top |
- Vanselow, K.H.
- Ricklefs, K.
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| Abstract |
In the final decades of the last century, an increasing number of strandings of male sperm whales (Physeter macrocephalus) around the North Sea led to an increase in public interest. Anthropogenic influences (such as contaminants or intensive sound disturbances) are supposed to be the main causes, but natural environmental effects may also explain the disorientation of the animals. We compared the documented sperm whale strandings in the period from 1712 to 2003 with solar activity, especially with sun spot number periodicity and found that 90% of 97 sperm whale stranding events around the North Sea took place when the smoothed sun spot period length was below the mean value of 11 years, while only 10% happened during periods of longer sun spot cycles. The relation becomes even more pronounced (94% to 6%, n = 70) if a smaller time window from November to March is used (which seems to be the main southward migration period of male sperm whales). Adequate chi-square tests of the data give a significance of 1% error probability that sperm whale strandings can depend on solar activity. As an alternative explanation, we suggest that variations of the earth's magnetic field, due to variable energy fluxes from the sun to the earth, may cause a temporary disorientation of migrating animals. |
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