Whale age at sexual maturity is one of the most important biological parameters that can be used in stock management and population analysis. Earplugs have been widely used as an indicator of age among rorquals. It ha...Whale age at sexual maturity is one of the most important biological parameters that can be used in stock management and population analysis. Earplugs have been widely used as an indicator of age among rorquals. It has also been accepted that the transition phase in the earplug can be used as an indicator of age at sexual maturity in fin whales, sei whales, and Antarctic minke whales. This study aimed to provide further insight into the utility of the transition phase as an indicator of age at sexual maturity in the North Pacific common minke whales, which has not yet been clarified. The relationship between sexual maturity and transition phase in earplugs was examined using 981 readable earplugs from common minke whales that were sampled at the JARPN and JARPN II scientific permit survey platform in the western North Pacific from 1994 to 2011. The transition phase was recognized in 53.2% of mature males and in 58.6% of mature females. Most whales in which the transition phase was recognized in the earplug were sexually mature. A significant correlation was found between the number of corpora and time after sexual maturation, as revealed by the transition phase, demonstrating that the transition phase is a valid indicator of age at sexual maturity in common minke whales. However, it was difficult to recognize the transition phase in whales that had recently attained sexual maturity because insufficient time had elapsed since its formation. To avoid potential bias, the use of earplugs as an indicator of age should be restricted to whales more than 12 years old.展开更多
On January 12,2011,a very young juvenile Bryde's-like baleen whale was found stranded alive on the east coast of Hainan Island,in the South China Sea.Unfortunately,it died the next morning.This baleen whale showed...On January 12,2011,a very young juvenile Bryde's-like baleen whale was found stranded alive on the east coast of Hainan Island,in the South China Sea.Unfortunately,it died the next morning.This baleen whale showed some unique external morphology and skull features of the Omura's whale(Balaenoptera omurai).Subsequently,it was genetically identified as an Omura's whale using two different mitochondrial DNA markers.This study documents the first confirmed live stranding of a juvenile Omura's whale on Hainan Island,China.Our findings expand the known distribution range of this species in Chinese waters and may indicate that waters around Hainan Island in the South China Sea could be a potential breeding ground for the Omura's whale.展开更多
文摘Whale age at sexual maturity is one of the most important biological parameters that can be used in stock management and population analysis. Earplugs have been widely used as an indicator of age among rorquals. It has also been accepted that the transition phase in the earplug can be used as an indicator of age at sexual maturity in fin whales, sei whales, and Antarctic minke whales. This study aimed to provide further insight into the utility of the transition phase as an indicator of age at sexual maturity in the North Pacific common minke whales, which has not yet been clarified. The relationship between sexual maturity and transition phase in earplugs was examined using 981 readable earplugs from common minke whales that were sampled at the JARPN and JARPN II scientific permit survey platform in the western North Pacific from 1994 to 2011. The transition phase was recognized in 53.2% of mature males and in 58.6% of mature females. Most whales in which the transition phase was recognized in the earplug were sexually mature. A significant correlation was found between the number of corpora and time after sexual maturation, as revealed by the transition phase, demonstrating that the transition phase is a valid indicator of age at sexual maturity in common minke whales. However, it was difficult to recognize the transition phase in whales that had recently attained sexual maturity because insufficient time had elapsed since its formation. To avoid potential bias, the use of earplugs as an indicator of age should be restricted to whales more than 12 years old.
基金supported by grants from the National Natural Science Foundation of China(No.31870372)the Bureau of Science&Technology for Development,Chinese Academy of Sciences(No.ZSSD004).
文摘On January 12,2011,a very young juvenile Bryde's-like baleen whale was found stranded alive on the east coast of Hainan Island,in the South China Sea.Unfortunately,it died the next morning.This baleen whale showed some unique external morphology and skull features of the Omura's whale(Balaenoptera omurai).Subsequently,it was genetically identified as an Omura's whale using two different mitochondrial DNA markers.This study documents the first confirmed live stranding of a juvenile Omura's whale on Hainan Island,China.Our findings expand the known distribution range of this species in Chinese waters and may indicate that waters around Hainan Island in the South China Sea could be a potential breeding ground for the Omura's whale.
