In fact, entanglement and death in gillnets, purse-seine nets, traps, weirs, longlines and trawls threatens 86 percent of all toothed whale species, finds the report, posted on the website of the Convention on the Conservation of Migratory Species of Wild Animals, CMS, often called the Bonn Convention after its headquarters city.
The Yangtze dolphin, or Baiji, is now considered extinct. (Photo courtesy CMS)
This is a substantial increase in toothed whale species at risk of dying as fishing by-catch as compared to 2001, when by-catch was reported to affect 50 species or 70.4 percent of all toothed whales, says author Boris Culik.
Lack of food and forced changes in diet as a result of overfishing pose additional threats to 13 of the world's 72 toothed whale species, his report finds.
This peer-reviewed encyclopedia on all 72 species of toothed whales includes the most recent scientific findings on the distribution, migration, behavior and threats to this group of whales.
But for 41 of all toothed whales species, the assessment shows that human knowledge is too limited even to know if these species are threatened or not.
"During the International Year of Biodiversity, the Convention on Migratory Species continues to address major threats such as by-catch, ship strikes, ocean noise impacts and climate change to safeguard these charismatic marine mammals," said UNEP/CMS Executive Secretary Elizabeth Mrema.
"Governments need to enhance their efforts towards implementing targeted action plans under the Convention," she said.
The report includes the sperm whale as the only large toothed whale as well as the Australian snubfin dolphin and the Guiana dolphin as new species.
Toothed whales inhabit marine and freshwater habitats, from the Arctic to the tropics. Some species live in large river systems such as the Amazon, Ganges, Indus and Yangtze.
A La Plata dolphin killed as by-catch in a fishing net, Brazil 2008. (Photo by Alan Cepile)
Many populations of toothed whales were at one point hunted almost to extinction and 50 species continue to be hunted, often at unsustainable levels, the report finds.
More recently, the ingestion of plastic debris or the effects of pollution by an ever-increasing cocktail of chemicals have been reported in 48 toothed whale species.
Pollution by persistent and bio-accumulating heavy metals, including mercury and butyltins used in anti-fouling paint for ships, as well as persistent chemicals such as PCB's, DDT and others, were found to affect 48 toothed whale species, as compared to 40 species in 2001.
Habitat degradation from dams and withdrawal of water from rivers and lakes threatens 18 species, the new report finds.
Ship strikes have a serious impact on 14 species, and noise caused by seismic explorations, marine construction projects and military sonar pose increasingly greater threats to these marine mammals.
At the same, time six species of toothed whales that are listed on Appendix I of the Convention are on the brink of extinction. They are:
Among the small cetacean species, there have been three additions and several changes since 2001. Perrin's beaked whale (Mesoplodon perrini) was first described in 2002 on the basis of five animals stranded on the coast of California.
The Australian snubfin dolphin (Orcaella heinsohni), formerly included in the Irrawaddy dolphin (Orcaella brevirostris) and the Guiana dolphin (Sotalia guianensis), formerly included in the Tucuxi (Sotalia fluviatilis) have been recognized as new species.
Two species have been synonymized with others and re-assigned to subspecific status - the Arabian common dolphin (Delphinus tropicalis) is now included in the Long-beaked common dolphin (Delphinus capensis) and the account on the Indo-Pacific humpback dolphin (Sousa plumbea) was merged with that of the Chinese white dolphin (Sousa chinensis).
Report contributors include CMS, and treaty organizations covering cetaceans in the Black Sea, Mediterranean Sea and Atlantic Ocean, the Baltic and North Seas, and the Pacific Ocean, the International Union for the Conservation of Nature, WWF-World Wide Fund For Nature, and the Loro Parque Foundation.
Being an official partner of the UN's International Year of Biodiversity, the Convention on Migratory Species has joined the Convention on Biological Diversity to raise awareness of the importance of biodiversity on a global scale.
Click here to read Boris Culik's report Odontocetes. The toothed whales: "Platanista gangetica." UNEP/CMS Secretariat, Bonn, Germany.
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