|
The New Zealand longfin eel (''Anguilla dieffenbachii'') is New Zealand's only endemic freshwater eel.〔(【引用サイトリンク】url=http://www.kcc.org.nz/eels-0 )〕〔Watene, E. (2003). Potential for Commercial Eel Aquaculture in Northland. Auckland: National Institute of Water and Atmospheric Research.〕 The other species of eel found in New Zealand are the native Shortfin eel (''Anguilla australis'') which is also found in Australia, and the sporadically naturally introduced Australian Longfin eel (''Anguilla reinhardtii'').〔(【引用サイトリンク】url=http://www.niwa.co.nz/freshwater-and-estuaries/nzffd/NIWA-fish-atlas/fish-species/australian_longfin_eel )〕〔〔Jellyman, D. J. (2007). Status of New Zealand fresh-water eel stocks and management initiatives. ''ICES J. Mar. Sci.,'' fsm073. 〕〔Glova, G. J., Jellyman, D. J., & Bonnett, M. L. (1998). Factors associated with the distribution and habitat of eels (''Anguilla'' spp.) in three New Zealand lowland streams. ''New Zealand Journal of Marine and Freshwater Research, 32''(2), 255 - 269.〕 The easiest method for identification of the New Zealand longfin eel is by the length of its fins: the dorsal (top) fin extends significantly further forward towards the head than the anal (bottom) fin. In the shortfin eel the fins are of similar length.〔McDowall, R. M. (1990). ''New Zealand freshwater fishes: a natural history and guide'' (Rev. ed.). Auckland: Heinemann-Reed.〕 The New Zealand longfin eel is classified by the Department of Conservation as "At Risk: Declining" under criteria "C(2/1) Total area of occupancy > 10 000 ha (100 km2), predicted decline 10–70%". ==Description== Male and female Longfin Eels differ in length and in the age at which they migrate with males averaging 666 mm but reaching up to 735 mm in length with an average age of 23 years (12 – 35 years).〔〔 Female Longfin Eels are considerably larger with an average length of 1156 mm, but can range from 737 to 1560 mm. These females range in age from 20 to 60 years before migrating.〔 The average age of migration varies between the North and South Islands of New Zealand with the North Island eels having younger migration ages and thus faster generation times.〔Jellyman, D. J. (2007). Status of New Zealand fresh-water eel stocks and management initiatives. ''ICES J. Mar. Sci.'', fsm073. 〕 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「New Zealand longfin eel」の詳細全文を読む スポンサード リンク
|