Whale stranding
A whale stranding is understood to mean the accidental emergence of a whale on the beach or a shoal . The best known are the mass strandings of pilot and sperm whales . The causes of whale strandings have not yet been adequately clarified. Possible reasons for mass or single stranding are:
- Toxic contamination within the food chain
- debilitating parasite infestation in the respiratory tract , brain or middle ear
- bacterial or viral infections
- panicked escape from enemies (including humans)
- strong social bonds within a group, whereby all individuals follow a stranded animal
- Disruption of the magnetic sense due to natural anomalies in the earth's magnetic field
- Injuries; For example, through collisions with ship propellers .
- Underwater noise pollution of underwater sound by shipping traffic, seismic surveys and military sonar experiments .
Sperm whales have been stranded in the North Sea since the end of the 16th century. These occurred mainly in the winter months between November and February during the male migration to the south.
Since the 1990s, whale strandings have occurred more frequently in connection with military sonar tests . In December 2001, the US Navy admitted complicity in the stranding and death of several marine mammals in March 2000. The interim report, which she co-authored, concluded that the animals were killed or injured by the active sonar of some Navy ships. In general, underwater noise, which is still on the rise, is increasingly being blamed for stranding, as it impairs communication and the animals' sense of direction .
Even the climate change shines through the influence of the big wind systems to guide the earth and thus the course of ocean currents to whale strandings. Mark Hindell and his team from the University of Tasmania in Hobart investigated whale strandings on the coast of Tasmania between 1920 and 2002 and found that larger stranding events occurred at certain time intervals. In the years with ten times the number of stranding events, the occurrence of strong storms was also registered, which increasingly directed the cold water currents near the coast. In nutrient-rich, cold water, whales find a particularly large number of prey, which is why they followed the cold water currents and thus reached shallower waters than usual in these meteorologically exceptional years, where the risk of stranding is higher.
Since many whales and dolphins live in groups , they often follow or accompany sick or weakened animals into shallow waters, which can lead to mass stranding at low tide .
Once stranded, large whales in particular are crushed by their own body weight if they cannot be plunged back into the deeper water in time. In addition, the regulation of body temperature is no longer guaranteed in a stranded whale and there is a risk of overheating.
Specific cases
- Whale strandings on the North Sea coast in 2016
- Whale strandings in Haast (New Zealand) 2017/18
- Whale strandings in Stewart Island (New Zealand) 2018
- January to the end of May 2019 around 70 gray whales in California, Oregon, Washington and Alaska - a similar number most recently in 2000
- 50 pilot whales (dead in the sand) spotted on Löngufjörur beach on the Snaefellsnes peninsula north of Reykjavik, Iceland, on July 18, 2019
See also
Individual evidence
- ↑ Injured whale redeemed through euthanasia. In: wochenblatt.es . April 25, 2019. Retrieved May 26, 2019 .
- ↑ Joseph G. Schnitzler, Marianna Pinzone, Marijke Autenrieth, Abbo van Neer, Lonneke L. IJsseldijk, Jonathan L. Barber, Rob Deaville, Paul Jepson, Andrew Brownlow, Tobias Schaffeld, Jean-Pierre Thomé, Ralph Tiedemann, Krishna Das, Ursula Siebert: Inter-individual differences in contamination profiles as tracer of social group association in stranded sperm whales. In: Scientific Reports. 8, 2018, doi : 10.1038 / s41598-018-29186-z .
- ↑ heise.de: U-boat tracking device kills whales from January 14, 2002, accessed on September 2, 2013.
- ↑ bahamaswhales.org: Joint Interim Report, Bahamas Marine Mammal Stranding, Event of 15-16 March 2000 ( Memento of the original from October 4, 2013 in the Internet Archive ) Info: The archive link was automatically inserted and not yet checked. Please check the original and archive link according to the instructions and then remove this notice. (PDF; 1.6 MB) December 2001, accessed on September 2, 2013.
- ^ Ocean Noise Coalition , November 26, 2007
- ^ New Scientist, July 26, 2004
- ↑ Riddles about the cause: 50 dead pilot whales discovered in Iceland orf.at, July 20, 2019, accessed July 20, 2019.
- ↑ Riddles about the cause: 50 dead pilot whales discovered in Iceland orf.at, July 20, 2019, accessed July 20, 2019.
