Peruvian beaked whale
Peruvian beaked whale (also well known as the pygmy beaked whale and Lesser Beaked Whale; scientific name: Mesoplodon peruvianus) is one of 21 species of beaked whales (Hyperoodontidae or Ziphiidae), medium-sized whales with distinctive, long and narrow beaks and dorsal fins set far back on their bodies. They are marine mammals within the order of cetaceans.
Little is known about Peruvian beaked whale due to its inaccessible habitat and elusive nature. The blow of the Peruvian beaked whale is also inconspicuous, making it hard to spot (Cetacea, 2001). The species avoids watercraft and can be mistaken for members of other Mesoplodon species. It is sometimes mistaken for Hector's beaked whale.
Scientists have examined 13 dead specimens, and few reliable sightings have been recorded. All recorded strandings have involved single individuals, but the species can be spotted in groups of two to three, with the third usually being a calf.
At birth, the Peruvian beaked whale is between 1.5-1.6 meters (m) long, while the adult is between 3.4-3.7 m. This whale is the smallest species of Mesoplodon (World Biodiversity Database, 2001).
This species is, on its upper side, uniformly dark gray fading to light gray on the underside (dark gray posterior to the navel). The body is spindle-shaped. The short, dark-tipped beak precedes a narrow head with an indentation at the blowhole.
This species has two tiny teeth on its lower jaw. The small, triangular dorsal fin has a wide base and is positioned far behind the center of this marine mammal. The flukes have no notches, and their tips are slightly pointed. (All information from Texas A&M University - Corpus Christi, 2001 unless otherwise noted.)
The Peruvian beaked whale exhibits sexual dimorphism. The males of the species are larger than the females (World Biodiversity Database, 2001).
Other Physical Features: Endothermic; Bilateral symmetry
Distribution and movements
Strandings and captures have taken place between 11 and 15 degrees south latitude, off the coast of central and southern Peru. This is thought to be the southern end of the range of Peruvian beaked whale (Texas A&M University - Corpus Christi, 2001)
However, "there is a single record of a stranding in New Zealand (Baker and Van Helden 1999), possibly suggesting that this species may have a more extensive distribution than previously believed. Alternatively, the New Zealand record may be an extralimital wandering." (IUCN)
This species lives in mid- to deep-sea waters off of the Peruvian coast.
Habitat Regions: Tropical; Saltwater or marine
Aquatic Biomes: Pelagic
Although feeding by the Peruvian beaked whale has not been witnessed, it is believed that this species eats mid- to deep-sea fish and squid (Cetacea, 2001).
Animal Foods: Fish; Mollusks
Humans are the only known threat to the Peruvian beaked whale. This whale becomes tangled in fishing nets, which initially led to the discovery of this species
Threats and conservation status
The IUCN Red List reports:
Some pygmy beaked whales are caught incidentally in drift gillnets for sharks off Peru (Reyes et al. 1991).. Entanglement in fishing gear, especially gillnets in deep water (e.g., for billfish and tuna), is probably the most significant threat.
There is no information on global abundance or trends in abundance for this species. It is not believed to be uncommon but it is potentially vulnerable to low-level threats and a 30% global reduction over three generations cannot be ruled out
In recent years, there has been increasing concern that loud underwater sounds, such as active sonar and seismic operations, may be harmful to beaked whales (Malakoff 2002). The use of active sonar from military vessels has been implicated in mass strandings of a number of beaked whales including several Mesoplodon species and Indopacetus pacificus (Balcomb and Claridge 2001, Jepson et al. 2003, Cox et al. 2006, Wang and Yang 2006). Sound impacts may be important for all ziphiid species.
Pygmy beaked whales have been recorded ingesting plastic items, which may eventually lead to death (e.g. Scott et al. 2001).
Potential impacts of global climate change on the marine environment may affect this species of whale, although the nature of impacts is unclear (Learmonth et al. 2006).
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