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The southern resident killer whales (SRKW) represent the smallest of four resident communities within the Northwestern portion of North America Pacific Ocean. It is the only killer whale population listed as endangered by the U.S. Fish & Wildlife Service. It is currently protected under the Endangered Species Act as of 2005. They are commonly referred to as the "orcas of the Salish Sea", "fish-eating orcas", or the "SRKW" population. Unlike other resident communities, the SRKW is only one clan (J) that consists of 3 pods (J, K, L) with several matrilines within each pod.〔http://www.nmfs.noaa.gov/pr/pdfs/recovery/whale_killer.pdf.〕 There are approximately 80 individuals that make up this small population. The world's oldest known killer whale, Granny or J2, belongs to J pod of the SRKW population.〔http://www.people.com/people/mobile/article/0,,20817101,00.html〕 Estimated to have been born around 1911, J2 is about 103 years old. == Social structure == Photo identification over the last 38 years has allowed researchers to track the southern resident population quite accurately, such as the Orca ID site offered through the Center for Whale Research. Their population is built upon a matrilineal system where these strong hierarchical groups of individuals are connected by maternal descent. Each matriline consists of a female, her sons and daughters and the offspring of her daughters; averaging anywhere from one to seventeen individuals and one to five generations within each of these matrilines.〔 Pods are groups of matrilines that share a maternal ancestor, in which the southern residents consist of three pods. The number of individuals changes due to birth and deaths. The Orca Network provides a list (last updated September 6, 2014). The following is the basic social structure:〔http://www.orcanetwork.org/news/birthsdeaths.html〕 ;Community : Southern Resident ;Clan : J ;Pods : J Pod ''(27 members)'' : K Pod ''(19 members)'' : L Pod ''(35 members)'' ;Matrilines :J2, J4, J5, J7, J10, J11, J32 (found dead on a beach on Vancouver Island on December 4, 2014.) :K4, K7, K8, K11, K18 :L2, L4, L9, L12, L21, L25, L26, L28, L35, L37 In 2014, L120 was born into L pod but didn't survive more than a month. In late 2014, J50 was born into the J pod. After a lot of speculation, J16 was confirmed to be J50's mother, making the 42-year-old the oldest ever recorded orca mother. The gender of the calf is confirmed to be female.〔http://www.modvive.com/2015/01/07/endangered-species-hope-birth-baby-killer-whale/〕 In February of 2015, two new calves were spotted, a male calf in J pod, designated J51, and one in L pod, designated L121. J51's mother is ten-year-old J41 Eclipse and L121's mother is year old L94 Calypso. A fourth calf, designated J52 was born in March 2015 to J36 Alki, who is J16's daughter. The genders of L121 and J52 are unknown. 抄文引用元・出典: フリー百科事典『 ウィキペディア（Wikipedia）』 ■ウィキペディアで「Southern resident killer whales」の詳細全文を読む スポンサード リンク
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