— Wildlife Sightings (@wildlife_uk) August 6, 2014
One of our contributors, Dr Matthew Bishop was excited to spot 2 killer whales off Gills Bay, Orkney this week.
This is not the first sighting of the year with moderately sized pods being recorded off Hermaness, Lerwick, South Harris and Firth.
The Killer Whale, Orcinus orca, or simply Orca, is the largest member of the Oceanic Dolphin family easily recognised by their distinctive tall, straight dorsal fins (in males, female dorsal fins are shorter and more curved) and black colouration with white patches above the eye, chin and underbelly with a grey ‘saddle’ behind their dorsal fin.
The species has a global distribution from Arctic and Antarctic to the Tropics yet individual family pods remain within a relatively localised area resulting in the development of different distinctive groups that rarely interbreed. Studies suggest that due to this different familial groups have developed into genetically identifiable subspecies, or ‘races’ with distinctive behaviours (reminiscent of human culture) and accents (recognisable as languages). The IUCN report 2008 recognised that “The taxonomy of this genus is clearly in need of review, and it is likely that O. orca will be split into a number of different species or at least subspecies over the next few years.”
A report (“Ecological, morphological and genetic divergence of sympatric North Atlantic killer whale populations“) published in Molecular Ecology from 2009 puts forward a strong case for two species of Orca frequenting UK waters. The main evidence for this being analysis of tooth wear, and diet using a method called stable isotope analysis with population ‘A’ exhibiting severe wear from “sucking up” fish species such as herring and mackerel whereas the significantly larger group ‘B’ individuals that feed on marine mammals such as seals showing virtually no tooth wear even in older individual.
It is without a doubt that Orcas have a dramatic impact on the human psyche and have left an impression on our culture, for some they have even become culturally significant with indigenous North American and Siberian groups incorporating them into their understanding of the world from holding them as deities and spirits of loved one to benevolent hunting companions. In the West, Ancient Greek tradition is responsible for their ‘Killer’ imagine with Pliny the Elder submitting them to text as savage beasts, yet very few attacks have been reported involving Orcas in the wild with no human fatalities. A Hollywood attempt at a sensationalist and bloody Orca ‘Jaws’ flopped in 1977. Real interest in Orcas started to rise in 1970s with scientists beginning to appreciate their intelligence and complex family relationships whereas others spotted their potential as the next big tourist attraction painting them as loveable circus acts, 67 individuals in captivity are recorded as being from wild-stock. The temporary climate leading away from keeping Orcas in captivity.
Threats to Orcas are as globally intrusive as their distribution. Historically their biggest threat was from whaling, as the population of large whales began to decline in the mid-20th century hunting of Orca became economically viable. Between 1954 and 1997 over 5000 individuals were killed by Japan, Norway and the Soviet Union. The International Whaling Commission recommended a ban on commercial hunting of Orca awaiting review of population, with no countries today holding permits or carrying out a substantial hunt yet countries such as Indonesia and Greenland permit small subsistence hunts of the species.
Orcas have also been targeted as a ‘pest’ species by fishermen and whalers blaming them for scavenging their catch promoting them to shoot at them on sight. The U.S Navy has admitted to killing hundreds of Orca in Icelandic waters during 1956 with contemporary sonar testing being criticised as causing harm.
The biggest current threat to the Orca population is from pollution and oil spills depleting their prey, and the consumption of contaminated prey causing chemicals to build up in their bodies to toxic levels. There have also been reports of death from propeller strike and boat collisions, entanglement in discarded fishing lives, disease and beaching.
11 days ago on the 28th July 2014 on Orca washed up on a beach in North Uist, the carcass does not show any significant signs of physical injury or propeller strike.Scientists thus far have been unable to identfy the cause of depth but after a superficial overview, a biologist from a Scottish Marine Animal Stranding Scheme (SMASS) remark to the press that the animal ‘looks a little thin.’ It is not yet known to which subspecies this individual belongs to.
Due to the significant genetic differences between subspecies IUCN has assessed their conservation status as Data Deficient putting forward an argument for individual assessment of subspecies. The most important conservation effort in place today is the monitoring of species by organisations such as Orca and the Whales and Dolphin Trust, providing information to our government and NGOs to allow them to make informed decisions about required habitat conservation and individual species protection.
2,281 total views, 3 views today
Latest posts by Samanta Webster (see all)
- Reintroduction success: Water Voles Return to Every English County - 28th August 2014
- Bioengineering an extinction event: Dengue Fever and GMO Mosquitos. - 18th August 2014
- Your photographs: Adders - 15th August 2014